WATER QUANTITY AND QUALITY REPORT Foothills Subarea

Transcription

1 WATER QUANTITY AND QUALITY REPORT Foothills Subarea Prepared for: Whatcom County Planning & Development Services Project No July 8, 008

2 79 Madrone Lane North Bainbridge Island, WA 980 Tel: (06) Fax: (06) a limited liability company

3 Contents Acronyms...iv Executive Summary... Water Quantity... Water Quality... Public Stormwater Facilities... Introduction... Existing Conditions...5. Water Quantity Surface Water Groundwater.... Water Quality Surface Water Quality Standards Groundwater.... Public Stormwater Facilities...6 Impacts Water Quantity Surface Water Groundwater Water Quality Surface Water Groundwater Public Stormwater Facilities Potential Mitigation Alternative Water Quantity Water Quality Public Stormwater Facilities Alternative Alternative Mitigation Elements Common to All Three Alternatives...6 PROJECT NO JULY 8, 008 i

4 Limitations...65 References...65 Endnotes...67 List of Tables E. Summary of Impacts and Possible Mitigation Measures...4. Population Density Statistics for the Foothills Subarea...4. Summary of Streamflow Records for the Foothills Subarea...6. Monthly Streamflow Statistics (all flows in cfs)...7. WRIA Water Balance applied to the Kendall Creek Watershed....4 WWHM Model Land Use Classifications for Existing Conditions....5 WWHM Simulated Annual Water Balance for the Columbia Valley/Kendall UGA....6 Public Water Systems in the Foothills Subarea Existing Water Use in the Columbia Valley/Kendall UGA Existing water use in the Rest of the Subarea Surface Water Use Designations (WAC 7-0A) EPA 0(d) Category 5 Listed Streams in the Foothills Subarea...9. Current and Prior Surface Water Temperature Standard for Foothills Subarea...0. Groundwater and Drinking Water Standards.... Well Head Protection Areas Having Potential Sources of Contamination Inventoried Culverts in the County Right-of-Way in the Columbia Valley/Kendall UGA Inventoried Culverts in the WSDOT Right-of-Way near the Columbia Valley UGA Inventoried Bridges in the WSDOT Right-of-Way near the Columbia Valley...8. Modeled Land Use for Columbia Valley/Kendall UGA Study Area (all values in acres)...4. Impervious Areas for Columbia Valley/Kendall UGA...44 ii PROJECT NO JULY 8, 008

5 . Land Use Classifications for Existing Conditions and Alternatives WWHM Simulated Annual Water Balance for the Columbia Valley/Kendall UGA WWHM Simulated Annual Water Balance assuming 00% infiltration of new runoff Existing and Future Water Use in the Columbia Valley/Kendall UGA Area Existing and Future Water Use in the Rest of the Subarea Nitrate Loading Analysis Assessment of Foothills Subarea Plan Goals and Policies related to Surface Water and Groundwater...6 List of Figures. Subbasins and Watersheds. Columbia Valley/Kendall UGA Overview. Geology and Surficial Aquifers.4 Well Logs by Quarter/Quarter Section.5 Water Temperature for Maple Creek Stormwater Inventory PROJECT NO JULY 8, 008 iii

6 Acronyms ADD...average daily demand BMPs...Best Management Practices BOD...biochemical oxygen demand CF...commercial forestry CFR...Code of Federal Regulations CSCL...Confirmed or Suspected Contaminated Sites List cfs...cubic feet per second DOH...Washington State Department of Health DU/acre...dwelling units per acre Ecology...Washington State Department of Ecology EIA...Effective Impervious Area EPA...U.S. Environmental Protection Agency EWSD#9...Evergreen Water-Sewer District #9 gpd...gallons per day LAMIRD...Limited Areas of More Intensive Rural Development LID...low impact development LUSTs...leaking underground storage tanks MCL...maximum contaminant level mg/l...milligrams per liter MIFs...Minimum Instream Flows NPDES...National Pollution Discharge Elimination System PWS...Public Water System RCW...Revised Code of Washington RF...rural forestry SEIS...Supplemental Environmental Impact Statement TOT...time of travel TP...total phosphorus TIA...total impervious area TSS...total suspended solids USC...United States Code USTs...underground storage tanks USGS...U.S. Geological Survey iv PROJECT NO JULY 8, 008

7 UGA...Urban Growth Area WAC... Washington Administrative Code WDFW... Washington State Department of Fish and Wildlife WSDOT... Washington State Department of Transportation WRIA... Watershed Resource Inventory Area WHPA... Wellhead Protection Areas WWHM... Western Washington Hydrology Model WCC... Whatcom County Code WCWD #... Whatcom County Water District # PROJECT NO JULY 8, 008 v

8 Executive Summary Whatcom County contracted with Aspect Consulting to perform a study of potential impacts to water quantity, water quality and public stormwater facilities associated with three different land use Alternatives under consideration for the Foothills Subarea. The study has three components:. A description of the existing environment in the Foothills Subarea including Surface Water Quantity, Groundwater Quantity, Surface Water Quality, Groundwater Quality, and Public Stormwater Facilities.. An evaluation of the significant adverse impacts to the existing environment related to three land use Alternatives: a. Alternative land use designations as proposed in the Draft Foothills Subarea Plan (October 007). b. Alternative existing land use designations. c. Alternative existing land use designations modified to specific Limited Areas of More Intensive Rural Development (LAMIRDs) and other rural designations.. An evaluation of potential reasonable mitigation measures for the significant adverse environmental impacts for each Alternative. The study includes the entire Foothills Subarea (Figure.), with additional attention on a focused study area consisting of,59 acres encompassing the Columbia Valley/Kendall UGA (Figure.). The results of this study will be used by Whatcom County to support the water quality/quantity and public stormwater facilities components of the Foothills Subarea Plan Supplemental Environmental Impact Statement (SEIS). Water Quantity The most significant impact to water quantity under all three Alternatives is a change in stormwater volume. Development of the natural environment increases the amount of impervious area in a watershed, which leads to increased stormwater runoff and decreased groundwater recharge. These impacts are most notable in the Columbia Valley Urban Growth Area (UGA)/Kendall Area, the area of most intense development under Alternatives and. Results from hydrologic simulations for the Columbia Valley/Kendall UGA indicate that stormwater runoff would increase under Alternatives and. If stormwater is discharged directly to surface water then groundwater recharge would decrease. Groundwater use would also increase under these Alternatives. These impacts could be mitigated effectively and reasonably by implementing low impact development (LID) strategies and/or controlling and infiltrating runoff consistent with state and county regulations. PROJECT NO JULY 8, 008

9 Flows in Kendall Creek, particularly during the low flow period, still may be significantly impacted depending on the timing of groundwater withdrawals and natural groundwater contributions to the stream. A quantitative groundwater model could be developed for the Columbia Valley/Kendall UGA to evaluate if and when impacts to Kendall Creek flows would occur and assist in the design of infiltration facilities to maintain baseflow in the stream. Water Quality The most significant risk to surface water quality under all three Alternatives is the introduction of stormwater pollutants to surface waters or groundwater through infiltration. These impacts are most likely to occur in the area of most intense development, the Columbia Valley/Kendall UGA under Alternatives and. These impacts could be mitigated effectively and reasonably by implementing LID strategies and/or runoff treatment prior to infiltration consistent with state and county regulations. More rigorous runoff treatment is recommended prior to infiltration in Critical Aquifer Recharge Areas and within ¼ mile of sensitive lakes. Additionally, new infiltration facilities should not be permitted within the -year time of travel of wellhead protection areas, or in high groundwater hazard areas. Other possible impacts to surface water quality include elevated water temperatures and sediment in streams near development. These impacts could be mitigated effectively and reasonably by the compliance with Whatcom County Code (WCC) 6.6 which establishes protective buffers of natural vegetation around streams. Protective buffers should also be implemented along all perennial tributaries to streams and rivers for the mitigation to be most effective. Groundwater withdrawals in the Columbia Valley/Kendall UGA also have the potential to decrease streamflow in Kendall Creek and subsequently increase water temperature. As previously discussed, mitigation measures for the reduction of Kendall Creek flows could require a quantitative groundwater model to design stormwater facilities to maintain baseflows and low water temperatures in the creek. Modeling of new non-sewered dwellings in the Paradise Lakes subdivision in the Columbia Valley/Kendall UGA predicts additional nitrate loading slightly exceeds state groundwater quality standards. A nitrate increase close to the allowable state standard is predicted for the WCWD # drainfield. This potential for nitrate increases should monitored. If monitoring indicates nitrate levels are likely to exceed state water quality standards, they could be effectively mitigated by providing sewer service to unsewered homes, by requiring enhanced nitrate removal (e.g., recirculating gravel filters) for the new on-site septic systems, or reducing density. Nitrate loading in the subarea outside the Columbia Valley/Kendall UGA has the potential to exceed groundwater quality standards, depending on the final development layout. Public Stormwater Facilities There are no significant impacts to existing stormwater facilities under any of the Alternatives analyzed. Historically, stormwater has been managed informally throughout the Foothills Subarea. In the Columbia Valley/Kendall UGA coarse soils allow for ready PROJECT NO JULY 8, 008

10 infiltration of stormwater and there are no existing public stormwater flow control facilities (e.g., detention/retention or infiltration ponds) or water quality treatment facilities. Limited conveyance features (e.g., culverts and ditches) are present in the county and state road rights-of-way. Since most, if not all, proposed development in the subarea will be private, additional pressure on these existing features should be minimal. It is not anticipated that any programs or capital facility improvements will be needed in the subarea over the 6- and 0-year planning periods. PROJECT NO JULY 8, 008

11 Table E- Summary of Impacts and Possible Mitigation Measures Alternatives Surface Water Quantity Alternative Potential Significant Environmental Impacts Increase in stormwater runoff Decrease in streamflow in Kendall Creek due to increased groundwater use in the Columbia Valley/Kendall UGA Possible Mitigation Measures Implement Low Impact Development (LID) strategies Implement runoff flow control BMPs in accordance with Ecology Manual Develop a quantitative groundwater model to determine the nature of impacts to streamflow and design infiltration ponds to maintain natural baseflows in Kendall Creek Intended Environmental Benefit of Mitigation Limits the increase in stormwater runoff Controls runoff to mimic the "natural condition" Maintain natural baseflows in Kendall Creek through specifically designed infiltration facilities. Unmitigated Significant Adverse Impacts None None, assuming the infiltration facility can be spatially located at appropriate distance from Kendall Creek. Use infiltration for stormwater management Recharge groundwater to offset increased withdrawals None Alternative Same as Alternative Same as Alternative Same as Alternative None Implement runoff flow Alternative control BMPs in Slight increase in stormwater Controls runoff to mimic the accordance with Ecology runoff "natural condition" Manual None 4 PROJECT NO JULY 8, 008

12 Table E- Summary of Impacts and Possible Mitigation Measures Alternatives Surface Water Quality Potential Significant Environmental Impacts Possible Mitigation Measures Intended Environmental Benefit of Mitigation Unmitigated Significant Adverse Impacts Alternative Increased water temperatures and sediment in streams near development Implement Habitat conservation buffers as outlined in WCC 6.6, plant riparian vegetation where buffers are not currently met Provide naturally vegetated separation between streams and development for stream shading and erosion control None Increased suspended solids and phosphorus in stormwater, may impact sensitive lakes. Increase in pollutant loads in stormwater runoff from new residential and commercial development Implement Enhanced Phosphorus Treatment for discharge directly to or infiltration within /4 mile of sensitive lakes Implement LID strategies Implement runoff treatment BMPs in accordance with Ecology Manual Reduce the phosphorus load to acceptable levels. Reduce the volume of runoff to be treated, keep runoff from non-pollution generating surfaces separate from runoff from pollution generating surfaces Provide appropriate level of stormwater pollutant removal prior to discharge None None Increase in pollutant loads in stormwater runoff from new industrial development Implement LID strategies Reduce the volume of runoff, provide runoff treatment, and separate runoff from pollution generating surfaces None PROJECT NO JULY 8, 008 5

13 Table E- Summary of Impacts and Possible Mitigation Measures Alternatives Potential Significant Environmental Impacts Possible Mitigation Measures Intended Environmental Benefit of Mitigation Unmitigated Significant Adverse Impacts Implement runoff treatment BMPs in accordance with Ecology Manual Provide appropriate level of stormwater pollutant removal prior to discharge Comply with Industrial Stormwater General NPDES Permit requirements Limits the discharge of pollutants to surface and ground water under the authority of Chapter RCW Potential direct discharge of pollutants from industrial activities Increase in water temperature in Kendall Creek due to reduced baseflows from increased groundwater use in the Columbia Valley/Kendall UGA Develop and implement site-specific Spill Plans for industrial sites Develop a quantitative groundwater model to determine the nature of impacts to streamflow and design infiltration ponds to maintain natural baseflows in Kendall Creek Use infiltration for stormwater management Decrease the likelihood of contaminant spills, establishes quick and effective spill response and cleanup Maintain natural baseflows in Kendall Creek through specifically designed infiltration facilities Recharge groundwater to offset increased withdrawals None None, assuming the infiltration facility can be spatially located at appropriate distance from Kendall Creek. None 6 PROJECT NO JULY 8, 008

14 Table E- Summary of Impacts and Possible Mitigation Measures Alternatives Potential Significant Environmental Impacts Possible Mitigation Measures Intended Environmental Benefit of Mitigation Unmitigated Significant Adverse Impacts Alternative Increased water temperatures and sediment in streams near development Implement Habitat conservation buffers as outlined in WCC 6.6, plant riparian vegetation where buffers are not currently met Provide naturally vegetated separation between streams and development for stream shading and erosion control None Increased suspended solids and phosphorus in stormwater, may impact sensitive lakes. Implement Enhanced Phosphorus Treatment for discharge directly to or infiltration within /4 mile of sensitive lakes Reduce the phosphorus load to acceptable levels. None Increase in pollutant loads in stormwater runoff from new residential development Implement LID strategies Implement runoff treatment BMPs in accordance with Ecology Manual Reduce the volume of runoff, provide runoff treatment, and separate runoff from pollution generating surfaces. Provide appropriate level of stormwater pollutant removal prior to discharge None Increase in water temperature in Kendall Creek due to reduced baseflows from increased groundwater use in Develop a quantitative Maintain natural baseflows in None the Columbia Valley/Kendall groundwater model to Kendall Creek through UGA determine the nature of specifically designed infiltration impacts to streamflow facilities. and design infiltration ponds to maintain natural baseflows in Kendall PROJECT NO JULY 8, 008 7

15 Table E- Summary of Impacts and Possible Mitigation Measures Alternatives Potential Significant Environmental Impacts Possible Mitigation Measures Creek Intended Environmental Benefit of Mitigation Unmitigated Significant Adverse Impacts Use infiltration for stormwater management Recharge groundwater to offset increased withdrawals None Alternative Increased suspended solids and phosphorus in stormwater, may impact sensitive lakes. Slight increase in pollutant loads in stormwater runoff from new residential development Implement Enhanced Phosphorus Treatment for discharge directly to or infiltration within /4 mile of sensitive lakes. Implement runoff treatment BMPs in accordance with Ecology Manual Reduce the phosphorus load to acceptable levels. Provide appropriate level of stormwater pollutant removal prior to discharge None None Groundwater Quantity Alternative Decrease in groundwater recharge due to increase in stormwater runoff Implement LID strategies Use 00% infiltration as runoff flow control BMP in accordance with Ecology Manual Promote distributed, more natural infiltration and recharge patterns Increase groundwater recharge. None 8 PROJECT NO JULY 8, 008

16 Table E- Summary of Impacts and Possible Mitigation Measures Alternatives Potential Significant Environmental Impacts Increased Groundwater Use Possible Mitigation Measures Use 00% infiltration as runoff flow control BMP in accordance with Ecology Manual Intended Environmental Benefit of Mitigation Volume of infiltrated stormwater offsets increased groundwater use Alternative Same as Alternative Same as Alternative Same as Alternative None Use 00% infiltration as runoff flow control BMP in accordance with Slight decrease in groundwater Ecology Manual Alternative recharge due to increase in Increases groundwater recharge. None stormwater runoff Unmitigated Significant Adverse Impacts None Groundwater Quality Alternative Introduce stormwater pollutants to groundwater through infiltration Implement LID strategies Use runoff treatment BMPs in accordance with Ecology Manual prior to infiltration Separate runoff from pollution generating surfaces, and provide runoff treatment Removes stormwater pollutants prior to infiltration None Introduce stormwater pollutants to groundwater water supplies through infiltration Use enhanced runoff treatment BMPs in accordance with Ecology Manual prior to infiltration Removes additional stormwater pollutants prior to infiltration None PROJECT NO JULY 8, 008 9

17 Table E- Summary of Impacts and Possible Mitigation Measures Alternatives Potential Significant Environmental Impacts Possible Mitigation Measures Intended Environmental Benefit of Mitigation Unmitigated Significant Adverse Impacts Additional nitrate loading from high-density individual septic systems associated with nonsewered dwellings (e.g., Paradise Lakes subdivision) and WCWD # drainfield. Monitoring is recommended to assess impact. If monitoring indicates likely exceedance of state water quality standards mitigate as shown Prohibit infiltration inside -year TOT wellhead protection areas Require enhanced nitrate removal for on-site septic (e.g., recirculating gravel filtration) Add infrastructure to ensure all new large development is on the sanitary sewer. Protects most sensitive areas of aquifer from potential adverse impacts Reduces nitrate concentrations in septic effluent, and overall nitrate loading Conveys all sewage to treatment plant for minimal impact to groundwater None None Alternative Introduce stormwater pollutants to groundwater through infiltration Implement LID strategies Use runoff treatment BMPs in accordance with Ecology Manual prior to infiltration Separate runoff from pollution generating surfaces Removes stormwater pollutants prior to infiltration None Introduce stormwater pollutants to groundwater water supplies through infiltration Use enhanced runoff treatment BMPs in accordance with Ecology Manual prior to infiltration Removes additional stormwater pollutants prior to infiltration None 0 PROJECT NO JULY 8, 008

18 Table E- Summary of Impacts and Possible Mitigation Measures Alternatives Potential Significant Environmental Impacts Possible Mitigation Measures Intended Environmental Benefit of Mitigation Unmitigated Significant Adverse Impacts Alternative Additional nitrate loading from high-density individual septic systems associated with nonsewered dwellings (e.g., the Paradise Lakes subdivision) and WCWD # drainfield. Monitoring is recommended to assess impact. If monitoring indicates likely impact of state water quality standards mitigate as shown Introduce stormwater pollutants to groundwater through infiltration Prohibit infiltration inside -year TOT wellhead protection areas Require enhanced nitrate removal for on-site septic (e.g., recirculating gravel filtration) Add infrastructure to ensure all new large development is on the sanitary sewer Use runoff treatment BMPs in accordance with Ecology Manual prior to infiltration Protects most sensitive areas of aquifer from potential adverse impacts Reduces nitrate concentrations in septic effluent, and overall nitrate loading Conveys all sewage to treatment plant for minimal impact to groundwater Removes stormwater pollutants prior to infiltration None None None Introduce stormwater pollutants to groundwater water supplies through infiltration Use enhanced runoff treatment BMPs in accordance with Ecology Manual prior to infiltration Prohibit infiltration inside -year TOT wellhead protection areas Removes additional stormwater pollutants prior to infiltration. Protects most sensitive areas of aquifer from potential adverse impacts None PROJECT NO JULY 8, 008

19 Table E- Summary of Impacts and Possible Mitigation Measures Alternatives Potential Significant Environmental Impacts Additional nitrate loading from high-density individual septic systems associated with nonsewered dwellings (e.g., the Paradise Lakes subdivision) and WCWD # drainfield. Monitoring is recommended to assess impact. If monitoring indicates likely impact of state water quality standards mitigate as shown Possible Mitigation Measures Require enhanced nitrate removal for on-site septic (e.g., recirculating gravel filtration) Add infrastructure to ensure all new large development is on the sanitary sewer Intended Environmental Benefit of Mitigation Reduces nitrate concentrations in septic effluent, and overall nitrate loading Conveys all sewage to treatment plant for minimal impact to groundwater Public Stormwater Facilities Alternatives, and None Identified None None None Unmitigated Significant Adverse Impacts None None PROJECT NO JULY 8, 008

20 Introduction Whatcom County is in the process of preparing a supplemental environmental impact statement (SEIS) to evaluate the impacts of adopting the Foothills Subarea Plan. The Foothills Subarea includes the Columbia Valley Urban Growth Area (UGA)/Kendall Area, the small towns of Glacier, Maple Falls and Deming, as well as rural lands, forestry lands, and recreational developments. The majority of the Subarea is located within the watersheds of the North and Middle Forks of the Nooksack River in Watershed Resource Inventory Area (WRIA). One of the purposes of an SEIS is to inform the public and decision makers of reasonable Alternatives that would avoid or minimize adverse impacts or enhance environmental quality. Whatcom County has identified three land use Alternatives that will be considered in the SEIS: Alternative is to adopt the comprehensive plan and zoning designations set forth in the Draft Foothills Subarea Plan as recommended by the Foothills Subarea Plan Advisory Committee in October 007. The UGA boundary for this alternative encompasses 9 acres. Alternative is to maintain the comprehensive plan and zoning designations set forth in the existing Whatcom County Comprehensive Plan and official Whatcom County Zoning Ordinance maps. The UGA boundary for this alternative encompasses 489 acres. Alternative removes the existing Columbia Valley/Kendall UGA designation and applies the "limited areas of more intensive rural development" (LAMIRD) criteria of the Growth Management Act to the Columbia Valley, Small Towns, and Resort/Recreational Subdivision designations. 4 The Columbia Valley LAMIRD boundary for this alternative encompasses 700 acres. Projected populations and number of dwellings for each Alternative are summarized in Table.. In this document the term Remaining Subarea refers to the portion of the Foothills subarea outside of the Columbia Valley/Kendall UGA and outside the Glacier, Maple Falls and Deming areas. This use of the term is consistent with the Draft Foothills Subarea Plan (October 007). The term Rest of the Subarea in this document refers to the entire Subarea outside the Columbia Valley/Kendall UGA. PROJECT NO JULY 8, 008

21 Table. Population Density Statistics for the Foothills Subarea Projected Population 5 Alternative Number of Dwellings 6 Area Columbia Valley/Kendall UGA 7,05 58 Glacier Maple Falls 54 0 Deming 6 00 Remaining Subarea,004 Projected Population Alternative Number of Dwellings Area Columbia Valley/Kendall UGA 5,8 09 Glacier 5 96 Maple Falls Deming 5 97 Remaining Subarea, Alternative Projected Population Number of Dwellings Area Columbia Valley/Kendall UGA 4, Glacier Maple Falls 0 9 Deming 8 9 Remaining Subarea,7 06 This study covers the entire Foothills Subarea. However, the main focus of this study is the Columbia Valley/Kendall UGA, because under each of the Alternatives it represents the area of most intense potential development (Table.). This report is organized as follows: Section Existing Conditions summarizes the existing surface water and groundwater quantity and quality in the Columbia Valley/Kendall UGA and rest of the subarea. Existing public stormwater facilities are also discussed. Section Impacts identifies the impacts of each land use Alternative to surface water and groundwater quantity and quality in the Columbia Valley/Kendall UGA and rest of the subarea. Impacts to public stormwater facilities are also discussed. Section 4 Potential Mitigation outlines potential mitigation measures for the impacts discussed in Section, for each land use Alternative. 4 PROJECT NO JULY 8, 008

22 Existing Conditions Existing water quantity and quality in the Foothills Subarea has been well documented as part of the WRIA Phase II technical studies prepared by Utah State University. WRIA encompasses the entire Nooksack River watershed system, of which the Foothills Subarea is a small portion. Other available sources of information that are more specific to the Foothills Subarea include groundwater studies for the Columbia Valley 7, Public Water System (PWS) data from the Washington State Department of Health (DOH), Washington State Department of Ecology (Ecology) well logs, Confirmed or Suspected Contaminated Sites List (CSCL), and 0(d) water quality assessments, and raw streamflow and water temperature data from the U.S. Geological Survey (USGS) and Ecology.. Water Quantity.. Surface Water The two primary watersheds in the Foothills Subarea are the North and Middle Forks of the Nooksack River (Figure.). The North and Middle Forks, combined with the South Fork (outside the Foothills Subarea) represent the headwaters of the primary water sources for parts of Whatcom County. Most notably, the City of Bellingham operates a diversion dam on the upper reaches of the Middle Fork to augment their water supply by diverting water into Lake Whatcom during the winter and spring. Other than the City of Bellingham diversion, surface water sources for water supplies are not common within most of the subarea; however, most groundwater withdrawals are located in alluvial aquifers that are in hydraulic continuity with nearby surface waters. Surface waters are also vitally important to salmonid species that are historically present in the Foothills Subarea. Two of these species, Chinook salmon and Bull Trout, are listed as threatened under the federal Endangered Species Act. Portions of the Sumas River, Sarr Creek, and Upper South Fraser watersheds are also in the Foothills Subarea and all drain north into Canada. These watersheds contain a relatively small portion of the total land area in the subarea. Streamflow There are stream gaging stations located within the Foothills Subarea with at least years of continuous streamflow data. These stations are summarized in Table.. The stations with the longest period of record are on the mainstem of the Nooksack River, and the North and Middle Forks. There is limited data available for smaller tributaries, although the USGS has active stations on Racehorse and Warm Creeks, and Ecology is currently maintaining a station on Maple Creek. Flows in the North Fork are dominated by seasonal snow and glacial melt, while flows in the Middle Fork and most other streams in the subarea are characterized by both PROJECT NO JULY 8, 008 5

23 precipitation and meltwater. Both Kendall and Maple Creeks originate from spring and precipitation fed lakes. Table. Summary of Streamflow Records for the Foothills Subarea Source of Data Station Number Drainage Area in square miles Period of Record Years of Record Source of Streamflow Station Name Subbasin NF Nooksack River below Cascade Creek, near Glacier present 69 NF G/S USGS NF Nooksack River near USGS Glacier 9 9; NF G/S USGS Kendall Creek at Kendall NF R USGS USGS 0700 USGS USGS USGS Racehorse Creek at North Fork Road, near Kendall present 8 NF G/S, R NF Nooksack River near Deming NF G/S, R Warm Creek near Welcome present 8 MF G/S, R Clearwater Creek near Welcome MF G/S, R MF Nooksack River near Deming ;90- ;94-5;954;965-70;99-present 7 MF G/S, R USGS Canyon Creek at Kulshan MF G/S, R Nooksack River at 96-57;958- USGS 0500 Deming MAIN G/S, R ECY 0K050 Maple Creek at mouth present 4 NF R ECY 0A40 Nooksack River above the Middle Fork present 4 NF G/S, R ECY 0G00 MF Nooksack River above Clearwater Creek MF G/S, R Note: Source of Streamflow: G/S - primarily from glacier and/or snow melt, R primarily from rainfall. 8 Monthly flow statistics for the period of record of each gaging station are presented in Table.. The 90-, 50-, and 0-percent exceedance flows for each month represent low, median and high flows, respectively. Exceedance flows represent the percent of time during a given month that flows are above the reported value. For example, during January, the mean daily flow in the North Fork (USGS # 95000) has been above 0 cubic feet per second (cfs) 90 percent of the time. Minimum Instream Flows (MIFs) have been established at nine locations within the Foothills Subarea (Washington Administrative Code [WAC] 7-50). MIFs are established by Ecology for the purposes of preserving wildlife, fish, scenic, aesthetic and other environmental values, and navigational values of perennial rivers and streams (RCW 90.). Where applicable, MIFs for a stream segment is also reported in Table.. 6 PROJECT NO JULY 8, 008

24 Table. Monthly Streamflow Statistics (all flows in cfs) North Fork Nooksack River below Cascade Creek near Glacier USGS # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average North Fork Nooksack River near Glacier USGS # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average Kendall Creek at Kendall USGS # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average MIF /6 4/ 5/6 7/8 9/0 Note: Control station for instream flow located at USGS # Kendall Creek at mouth Racehorse Creek at north Fork Road near Kendall USGS # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average MIF /80 80/ / /0 0/5 47/55 Note: Control station for instream flow located at WADOE # 0700 Racehorse Creek at mouth PROJECT NO JULY 8, 008 7

25 North Fork Nooksack River near Deming USGS # 0700 Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average MIF / Warm Creek near Welcome USGS # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average Clearwater Creek near Welcome USGS # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average Middle Fork Nooksack River near Deming USGS # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average MIF / / Canyon Creek at Kulsan USGS # 0500 Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % PROJECT NO JULY 8, 008

26 Average MIF /0 5/0 0 0/ 7/ 40/4 Nooksack River at Deming USGS # 0500 Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average MIF / / / / Maple Creek at mouth Ecology # 0K050 Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average MIF 0 0/ / North Fork Nooksack River above Middle Fork Ecology # 0A40 Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average Middle Fork Nooksack River above Clearwater Creek Ecology # 0G00 Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. Exceedance Flows 90% % % Average PROJECT NO JULY 8, 008 9

27 Bells Creek Ecology # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. MIF 4 4/ /4 5/6 6 / / /4 4 Cornell Creek Ecology # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. MIF /9 5/ 5/0 0 0 Gallop Creek Ecology # Month Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec. MIF /8 6/ / Kendall Creek Watershed The Kendall Creek watershed is an approximately.5-square mile basin bounded by Vedder Mountain to the north and the flanks of Sumas Mountain and Red Mountain to the west and east, respectively (Figure.). Approximately 6.5-square miles of the watershed are located in the Foothills Subarea, with the remaining area in Canada. The Columbia Valley is the broad, flat alluvial valley at the base of these mountains. Elevation ranges from approximately 400 feet at the mouth of Kendall Creek to,700 feet on the flanks of Sumas Mountain. Precipitation generally ranges from 60 to 70 inches per year throughout the watershed, although at higher elevations precipitation averages up to 90 inches per year. The Columbia Valley/Kendall UGA is located within the Kendall Creek watershed. The remaining area outside the Columbia Valley/Kendall UGA is primarily zoned forestry (rural forestry [RF] or commercial forestry [CF]) or rural (R5 or R0). Kendall Creek originates from springs and spring fed lakes (Kendall and Sprague Lakes) and wetlands near the southern end of the Columbia Valley. A majority of the wide valley bottom in the Kendall Creek watershed upgradient from Kendall Lake is flat, with no defined channel. 9 The watershed is unique in a number of ways from others in the Foothills Subarea. Most surface water tributaries to the North and Middle Forks of the Nooksack are located in narrow bedrock valleys where abundant runoff is generated via precipitation, snow melt and/or glacial melt. A significant portion of runoff that originates in the Columbia Valley percolates into the subsurface as groundwater recharge. The surficial soils in the Columbia Valley consist of coarse glacial outwash gravels 0 that readily infiltrate runoff. For example, the small creeks draining Sumas Mountain in the northern part of the watershed are known to infiltrate and disappear when they reach the valley floor. Streamflow records for Kendall Creek are available for a limited period (948 to 950) at one gage location (Kendall Creek at Kendall) as shown in Table.. This station has a drainage area of 4-square miles that includes a majority of the Columbia Valley/Kendall UGA. Streamflow statistics from those years indicate an average streamflow of 6 cfs 0 PROJECT NO JULY 8, 008

28 and very low flows of less than 5 cfs in late summer and fall with the Creek reported as dry in September through November 949. The MIF for Kendall Creek varies from cfs in late August and September up to 0 cfs in winter. The MIF was established at the mouth of Kendall Creek while the available streamflow data for the gage is located further upstream at Kendall Creek at Kendall Creek gage station. A water balance was developed for the Kendall Creek watershed upstream of the USGS Kendall gage based on the Utah State University WRIA study. The water balance quantitatively describes the partitioning of the water input (precipitation) into surface runoff, evaporation and plant transpiration (collectively referred to as evapotranspiration), and groundwater recharge. Results are presented in Table.. Each component was calculated in units of inches of water in the WRIA water quantity documents by USU. These results were extrapolated to the 4-square mile portion of the Kendall Creek watershed for this report. The results of water balance calculations indicate percent of precipitation generates runoff and approximately 45 percent of annual precipitation contributes to groundwater recharge. Table. WRIA Water Balance applied to the Kendall Creek Watershed (area above USGS Stream Gage Kendall Creek at Kendall) Water Volume Water Balance Component Inches per Year Acre-Feet per Year Cubic Feet per Second Precipitation 7 9,600 9 Runoff Range 9,00 5 8, Evapotranspiration 8,400 Range 4 0 4, Recharge 5 4, Note: Runoff evapotranspiration and recharge do not add up to precipitation because all parameters were calculated independently in the WRIA studies. The author s identified the most likely source of error as an overestimation of runoff for the watershed. 6 The Washington State Department of Fish and Wildlife (WDFW) operate the Kendall Creek Hatchery near the mouth of Kendall Creek, downstream of the USGS gage. According the WDFW personnel 7, Kendall Creek normally runs dry from the first part of June until flows return again in October. They report that Kendall Creek has flow later than mid-june in about 4 in 0 years, or 0 percent of the time, Kendall Creek has water past mid June. The hatchery uses both surface water from Kendall Creek and groundwater from five wells for their operations. All hatchery use is non-consumptive and hatchery water is returned to the stream approximately 50 feet downstream from the point of diversion. The hatchery discharge creates continuous flow in the lower reach of Kendall Creek, even in summer. The hatchery raises two endangered species of salmon the North Fork Spring Chinook and South Fork Spring Chinook. The South Fork fish are transferred to the hatchery for enhancement purposes. PROJECT NO JULY 8, 008

29 Stormwater Native forests, wetlands and other vegetated areas intercept, store and slowly convey precipitation through complex pathways. 8 Development of the natural landscape replaces native vegetation and soils with impervious roads, parking areas, sidewalks and rooftops as well as compacts soils and other changes to the pervious portions of the landscape. This transition from a native landscape to a developed environment increases stormwater volumes. Stormwater and surface runoff is currently managed informally throughout the Foothills Subarea, with drainage generally percolating into the soil or discharging to streams and rivers untreated. 9 This is typical of rural development in the Puget Sound lowlands. Stormwater runoff for each of the alternatives was estimated using the Western Washington Hydrology Model (WWHM). WWHM is a computerized hydrologic model that simulates hourly runoff, evapotranspiration and groundwater recharge based on a 50- year precipitation record. A key component of the WWHM analysis is defining the soil types, slopes, vegetated covers, and land uses within a basin. The study area for the WWHM simulations was defined as,59 acres that includes the Columbia Valley/Kendall UGA. This area includes the,489 acre existing UGA (Alternative ) plus 40 additional acres that are included in the UGA under Alternative, east of the Paradise Lakes Subdivision (Figure.). For the existing condition, land uses were based on the existing development as of 006. The developed lands in the Campers Paradise, Paradise Lakes and Peaceful Valley subdivisions currently zoned UR4 in the Columbia Valley/Kendall UGA were assumed to have a density of.4 units per acre. 0 This density was calculated by dividing the total number of developed lots and recreational sites (,66 total lots ) by 700 acres of existing platted development. For the hydrologic model, this area was assumed to be 6% impervious roads, 5% impervious roofs, 4 and % impervious driveways, 5 with the remaining area consisting of grass-covered outwash soils. The remaining portions of the modeled area were simulated as follows: For the 4 acres of the existing Kendall Small Town,. acres were modeled as impervious 6 and the remaining 0.9 acres outwash grass. 76 acres around Kendall, assuming 0% impervious distributed between roads (7%), roofs (.5%) and driveways (.5%). 69 acres of remaining area were modeled as forested outwash soils. With these assumptions, the total impervious area (TIA) under existing conditions is estimated at 87 acres. However, Effective Impervious Area (EIA) is more important than TIA for predicting stormwater runoff. EIA is defined as the impervious area that is hydraulically connected via sheet flow or discrete conveyance to a drainage system or receiving body of water. 7 For example, if splash blocks are used to disperse runoff from roofs to vegetated areas, then the roof is not directly connected to the stormwater conveyance system and the impervious roof surface is part of the TIA, but not part of the EIA. The typical ratio of EIA to TIA for is 0.66 for existing developments up to 4 DU/acre 8, and 0.04 for existing rural development 9. The balance of the impervious area (TIA minus EIA) was simulated as grass-covered outwash. PROJECT NO JULY 8, 008

30 The resulting land uses included in the hydrologic model for existing conditions are presented in Table.4. Table.4 WWHM Model Land Use Classifications for Existing Conditions Roads Runoff Modeling Land Use Classifications Effective Impervious Areas in Acres Pervious Areas in Acres Stormwater Ponds Driveways Roofs Outwash Grass Outwash Forest Existing Conditions The results of the WWHM simulations for existing conditions in the Columbia Valley/Kendall UGA are presented in Table.5. These values will be used to assess the impacts of each alternative on runoff and groundwater recharge in the Columbia Valley/Kendall UGA in Section. Table.5 WWHM Simulated Annual Water Balance for the Columbia Valley/Kendall UGA Scenario Existing Conditions Water Volume Water Balance Component Inches per Year Acre-Feet per Year Cubic Feet per Second Precipitation 6. 7,9 0.9 Runoff Evapotranspiration 8.9,4. Groundwater Recharge 8.7 4, The annual water volume for each water balance component simulated by WWHM for the Columbia Valley/Kendall UGA (Table.5) varies from the results of the water balance for the entire Kendall Creek watershed (see Table.). The Kendall Creek watershed water balance was based on an area roughly 0 times larger than the Columbia Valley/Kendall UGA, including the forested mountains around the Columbia Valley. Including these areas results in higher precipitation, evapotranspiration, and runoff, with subsequently less groundwater recharge than the water balance for the Columbia Valley/Kendall UGA. The runoff volume predicted by the hydrologic model assumes that stormwater runoff from all EIA discharges directly to surface water. Given the gentle slopes and coarse soils of the Columbia Valley, it is likely that most of the runoff volume does not reach Kendall Creek or other streams and instead infiltrates to recharge groundwater... Groundwater The Foothills Subarea lies mostly within the region designated as the Eastern Highlands in the WRIA Phase II Groundwater Quantity Report. 0 This region is characterized by mountainous, steep topography that has been deeply incised by glacial erosion and by surface water drainages. Bedrock is comprised of metamorphosed Paleozoic sediments PROJECT NO JULY 8, 008

31 and volcanic rocks. Valley bottoms are narrow and lined with continental and alpine glacial deposits, alluvium and mass wasting deposits overlying bedrock up to 50 feet thick. Sediments are comprised of interbedded coarse gravels, sand, silt and clay. Regional Aquifer System Aquifers in this region are bounded vertically and laterally by bedrock (Figure.). Groundwater tables are near the surface, mostly in unconfined, coarse-grained aquifers associated with surface water bodies, such as the Nooksack River. Most wells are completed in layers of sand and gravel, at depths of less than 50 feet. Few wells are completed in bedrock as they generally produce little groundwater. The alluvial aquifers within the Eastern Highlands area are referred to as the Upper Valley aquifers. The Upper Valley aquifers are present along valley floors throughout most of the subarea, except Deming which lies at the eastern extent of the Sumas-Blaine Surficial Aquifer. The Sumas-Blaine surficial aquifer extends into the Whatcom County lowlands and is comprised of continental glacial drift. Groundwater flow directions in the Upper Valley Aquifers generally follow surface water drainages and are controlled by bedrock topography. Recharge occurs along the valley bottoms through coarse grained unconsolidated sediments. Average annual recharge across the entire subarea is estimated to be inches (Table.). In the Columbia Valley/Kendall UGA outwash, till, glaciomarine drift, peat and alluvial fan sediments comprise sequences of unconsolidated deposits, generally less than 50 feet deep, overlying bedrock. 4 Coarse-grained sands and gravels that at the surface serve as parent material for highly permeable top soil. Infiltration rates are high. Outwash deposits form an unconfined aquifer bounded by bedrock to the east and west. The groundwater surface mimics topography and water levels are generally less than 0 feet below the ground surface. Groundwater flow direction is to the south, with groundwater gradients (slope of the water table) ranging from 7 feet to feet per mile and the average linear velocity of 4.4 feet per day. 5 Less permeable landslide deposits that extend beneath the surface impede southerly groundwater flow in the area near Sprague and Kendall Lakes. 6 Lakes and streams are fed almost exclusively by groundwater. Average annual recharge within the Columbia Valley/Kendall UGA is estimated to be 8.7 inches (Table.5) and is greater than the entire subarea recharge of inches (Table.6) due to the flatter topography and higher infiltration rates associated with the more localized area. Groundwater discharges to Kendall and Sprague lakes, Kendall Creek and likely the Nooksack River. A recent hydrogeologic and wellhead protection evaluation was performed to evaluate the impact of a proposed development of 700 single-family and 00 multi-family residences to be serviced by Whatcom County Water District # (WCWD #) on 7 acres in the Columbia Valley/Kendall UGA. 7 The study characterized aquifer conditions, including groundwater flow directions and magnitudes, and quantified aquifer throughflow. The analysis also included nitrate loading from WCWD # sewage treatment plant drainfield under existing and proposed condition. 4 PROJECT NO JULY 8, 008

32 Groundwater Use Groundwater from wells or springs is the primary source of drinking water in the Foothills Subarea. Public water systems (PWS) within the Foothills Subarea consist of Group B and 4 Group A water systems (Table.6) 8. Residents in the Foothills Subarea not served by a public water system generally use exempt wells which are typically located in the alluvial aquifers near major streams and rivers shown in Figure.4. Table.6 Public Water Systems in the Foothills Subarea Water System Name PWS ID Group Calculated Connections 9 Approved Connections 40 Additional Approved Connections Black Mountain Ranch 077 A Caffe Rifugio Water System A unapproved 0 Camp Black Mountain 5707 A unapproved 0 Cascade West Recreation Club B 9 0 CFCI 0085 B 5 undetermined 0 Deming Log Show and RV 5675 A 4 unapproved 0 Deming Speedway Water System 0479 B undetermined 0 Deming Water Association 8800 A Douglas Fir Campground- East FS7 A undetermined 0 Douglas Fir Campground- West FS9 A undetermined 0 Evergreen Water-Sewer Dist #9 660 A Glacier Green Water District 768 B 0 8 Glacier Springs Water System 7755 A Glacier Water District 9595 A Glen Community Association 8777 A undetermined 0 Harmony Grade School 55 A 0 Hollingsworth Water Assoc B unapproved 0 Holy Smoke Bar and Grill A unapproved 0 Kendall Creek Salmon Hatchery B 5 undetermined 0 Kendall Elem School 085 A undetermined 0 Maple Falls Water Coop 500 A Mt Baker Bibleway Camp 560 A 46 unapproved 0 Mt Baker School District 0468 A 0 North Fork Water System 5759 A 0 Paradise Market 097 A 0 Red Mountain Estates Water System # 0664 B Red Mountain Estates Water System # B Riverview Water Assoc 5476 B 7 undetermined 0 Shady Ridge Assoc 46 B Silver Lake Park- Horse Camp 5666 A 7 unapproved 0 Silver Lake Park- Main Camp 5679 A 6 unapproved 0 PROJECT NO JULY 8, 008 5

33 Starvin Sams #5 Kendall Water Sys A 0 Teamousey Teapot 0645 B The Logs Resort 5680 B 7 unapproved 0 WCWD # 9594 A Total Columbia Valley/Kendall UGA Two Group A water purveyors, Evergreen Water-Sewer District #9 (EWSD#9) and Whatcom County Water District # (WCWD #), provide nearly all domestic water within the UGA. These water systems obtain their supply from 5 wells (Figure.) and provide,74 existing connections. In 006, there were,8 total dwellings (includes year-round, seasonal, recreational and occasional dwellings). 4 The number of existing public water system connections exceeds dwellings by ERU s. These nonresidential connections are likely recreational lots, primarily in Campers Paradise, that accommodate recreational vehicles and park models which aren t included in the total number of dwellings. 4 Existing water use was estimated for the Columbia Valley/Kendall UGA based on the following assumptions: All water service to the Columbia Valley/Kendall UGA is provided by WCWD # and EWDS#9. 4 Total water use was calculated based on an average daily demand (ADD) of 40 gallons per day (gpd) 44 for the,8 existing dwellings. Total return flow 45 was estimated at gpd per dwelling. 46 Total consumptive use was calculated as 8 gpd per connection based on the difference between the ADD and return flow rate. Non-Residential connections were assumed to be primarily recreational lots and have a total year round water use of 50 gpd. 47 No return flow was assumed for these connections. Total annual water use in the Columbia Valley/Kendall UGA was estimated to be 90 acre-feet. Return flow and consumptive use were estimated to be 89 acre-feet and 0 acre-feet, respectively (Table.7). Based on the water balance results (see Section..), the total consumptive water use represents approximately 4 percent of recharge within the Columbia Valley/Kendall UGA (Table.5) or approximately 0.5 percent of recharge in the Kendall Creek watershed above Kendall (Table.). 6 PROJECT NO JULY 8, 008

34 Table.7 Existing Water Use in the Columbia Valley/Kendall UGA Number of Water Volume in Acre-Feet per Year Total Number of Dwellings Non- Residential PWS Connections Total Number of PWS Connections Total Water Use Total Return Flow Total Consumptive Water Use Existing Condition,8, Rest of the Subarea In the existing condition, there are,09 year-round dwellings and 994 seasonal and unoccupied dwellings in the Foothills Subarea outside of the Columbia Valley/Kendall UGA. 48 This area also includes a large number of recreational lots that accommodate recreational vehicles and park models that are not included in the total number of dwellings. The Glen at Maple Falls and Black Mountain Ranch account for, and,0 of these lots, respectively. Based on PWS records, it is likely that there are an additional 69 non-residential or camping lots bringing the total to,6 non-residential PWS connections in the rest of the Subarea. 49 Existing water use was estimated for the rest of the subarea based on the number of yearround and seasonal/unoccupied dwellings, and number of recreational lots. Year-round dwellings were differentiated from recreational and seasonal/unoccupied dwellings to provide a more accurate estimate of water use. The following assumptions were used to estimate water use in Glacier, Maple Falls, Deming and the remaining subarea: The ADD for dwellings is based on 00 gpd as a conservative estimate from the Columbia Valley/Kendall UGA reduced in proportion to the total number of occupants in Glacier, Maple Falls, Deming and the remaining subarea. (For example: persons per dwelling in Glacier 50 /.7 per dwelling in the Columbia Valley/Kendall UGA for a total of gpd per dwelling.) Return flow of gpd (estimated from Columbia Valley/Kendall UGA) was similarly reduced for each area (i.e., gpd x /.7 = 84 gpd). Seasonal dwellings were assumed to be occupied 6 months of the year so the resultant average daily water use and return flow were divided by two. Non-residential PWS connections were assumed to be primarily recreational lots with a total year round water use of 50 gpd. No return flow was assumed for these connections. Total annual water use in the rest of the subarea was estimated to be 550 acre-feet. Return flow and consumptive use were estimated to be 59 acre-feet and 9 acre-feet, respectively (Table.8). PROJECT NO JULY 8, 008 7

35 Table.8 Existing Water Use in the Rest of the subarea Number Number of Number of Non- Water Volume in Acre-Feet per Year Location of Year - Round Dwellings Seasonal/ Unoccupied Dwellings Residential PWS Connections Total Water Use Total Return Flow Total Consumptive Water Use Existing Condition,09 994, Water Quality.. Surface Water Quality Standards Surface water quality in Washington State is protected using a three part approach of: ) designating uses of a water body, ) assigning narrative and numerical water quality standards based on the designated uses, and ) establishing policies, such as antidegradation, to protect waters of higher quality than the standards. Washington s surface water quality standards are defined in WAC 7-0A. The applicable use designations for surface waters in the Foothills Subarea are shown in Table.9. Aquatic life uses affect the numerical criteria for temperature, dissolved oxygen, turbidity, total dissolved gas and ph. Recreation uses establish the numerical criteria for bacteria. All uses are protected by criteria that apply to toxic materials and aesthetic values. Table.9 Surface Water Use Designations (WAC 7-0A) Waterbody Aquatic Life Uses Recreation Uses Water Supply Uses Misc. Uses North Fork Nooksack River and all tributaries upstream to Maple Creek North Fork Nooksack River and all tributaries upstream of Maple Creek, including Maple Creek Core Summer Salmonid Habitat Char Spawning and Rearing Primary Contact Extraordinary Primary Contact Domestic, Industrial, Agricultural, Stock Wildlife Habitat, Harvesting, Commerce/ Navigation, Boating, Aesthetics Middle Fork Nooksack River and all tributaries Char Spawning and Rearing Extraordinary Primary Contact 8 PROJECT NO JULY 8, 008

36 Water Temperature The principal surface water quality concern in the Foothills Subarea is temperature, particularly in the tributaries to the North Fork and in the Middle Fork subbasin. Water temperatures in the glacially-derived North Fork generally meet temperature standards; but temperature can be elevated in summer in many tributaries to the North Fork. Elevated temperatures have also been observed in the Middle Fork and its tributaries. The 00/004 0(d) list identified water quality impaired reaches in the Foothills Subarea (Table.0). In the absence of specific studies, it is not possible to determine the exact cause of elevated temperatures; however, the WRIA Surface Water Quality Phase II Summary Report identified timber harvesting and other land use practices as possible causes. 5 These practices reduce vegetative cover and riparian shading and increase runoff which, in turn, increase the water surface area exposed to solar radiation and reduce stream depths. Forestry is a significant land use in the Foothills Subarea as 87 percent of land area is zoned for forestry (74 percent CF and percent RF). Table.0 EPA 0(d) Category 5 Listed Streams in the Foothills Subarea Waterbody Description Reason for Listing Bells Creek North Fork Tributary Temperature Canyon Creek Middle Fork Tributary Temperature Canyon Lake Creek North Fork Tributary Temperature Cornell Creek North Fork Tributary Temperature Gallop Creek North Fork Tributary Temperature Kendall Creek North Fork Tributary Temperature Kenney Creek North Fork Tributary Temperature Middle Fork Nooksack Temperature Porter Creek Middle Fork Tributary Temperature Racehorse Creek North Fork Tributary Temperature and Fine Sediment Since the 00/004 0(d) list was prepared, Washington State has revised its surface water quality standards. Prior to the adoption of the current water quality standards, streams in the Foothills Subarea were designated as either Class A (Excellent) or Class AA (Extraordinary). The temperature criteria under the previous standard were higher than the current standard as outlined in Table. below. PROJECT NO JULY 8, 008 9

37 Table. Current and Prior Surface Water Temperature Standard for Foothills Subarea Waterbody Current Water Temperature Standard Prior Water Temperature Standard North Fork Nooksack River and all tributaries upstream to Maple Creek 6 C Class A - 8 C North Fork Nooksack River and all tributaries upstream of Maple Creek, including Maple Creek C Class AA - 6 C Middle Fork Nooksack River and all tributaries C Class AA - 6 C Since 004, Ecology has also collected surface water temperature data in Maple Creek. This data is in shown on Figure.5. During each year Ecology has collected data, water temperatures in Maple Creek have failed to meet the current standard for extended periods of time. However, water temperatures would have met the previous standard of 8 C Maple Creek WY 004 Maple Creek WY 005 Maple Creek WY 006 Maple Creek WY 007 Surface Water Quality Standard 7-DADMax Water Temperature in o C Oct 0-Nov 9-Jan 8-Feb 8-Apr 7-Jun 7-Jul 5-Sep Figure.5 Water Temperature for Maple Creek 0 PROJECT NO JULY 8, 008

38 Other Parameters The available data suggest surface water quality is good from a chemical and microbiological perspective, 5 although limited data are available for nutrients, suspended solids and turbidity. 5 One source of concern is nitrate loading from individual on-site septic systems located near streams like Kendall Creek in the Columbia Valley/Kendall UGA and Glacier Creek in the Mt. Baker Rim recreational subdivision near Glacier; however, nitrates in these streams have not been studied to date. Dissolved oxygen concentrations below the state standard of 9.5 milligrams per liter (mg/l) have been observed in many of the stream segments that are impacted by elevated water temperatures. 54 Dissolved oxygen is used for respiration by fish and other aquatic life, and higher concentrations are generally better. Low dissolved oxygen concentrations are typically caused by organic wastes that consume oxygen during degradation, or higher water temperatures that limit the solubility of oxygen. For streams in the Foothills Subarea, the correlation between high temperatures and dissolved oxygen concentrations below the state standard does not necessarily imply that dissolved oxygen concentrations are controlled solely by water temperature, but it does suggest that interrelated factors may be influencing both parameters. 54 Stormwater Quality As discussed above, stormwater and surface runoff is currently managed informally throughout the Foothills Subarea, with drainage percolating into the soil or discharging to streams and rivers untreated. 55 Stormwater quality plays an important role in the overall quality of surface waters in a region. Runoff from developed areas has the potential to become contaminated with sediment, metals, fertilizers and pesticides, oil and grease, and other chemicals. When stormwater infiltrates, either deliberately through engineered infiltration facilities, or unintentionally through exposed soils or unlined ditches, it can be a source of contaminants to groundwater. Ecology guidelines outline Best Management Practices (BMPs) that are designed to prevent stormwater from becoming contaminated (source control BMPs) and/or remove pollutants prior to discharge (runoff treatment). An example of a source control BMP is secondary containment around storage tanks. A runoff treatment BMP could be a bioswale or wetpond designed to remove sediments from stormwater. If stormwater pollution still occurs after implementing Ecology s BMPs to the extent practicable, discharge of contaminated stormwater is regulated under the National Pollution Discharge Elimination System (NPDES). NPDES was established by Section 40 of the Clean Water Act and codified in 40 CFR. The intent of the NPDES program is to achieve the Clean Water Act goal to restore and maintain the chemical, physical, and biological integrity of the Nation's waters [ USC 5 0(a)] by requiring permits for the discharge of pollutants from any point source into waters of the United States. [40 CFR.(b)] PROJECT NO JULY 8, 008

39 The program requires permits for wastewater and stormwater discharges from industrial sites, construction sites, and municipal storm sewer systems. The EPA has authorized individual states to administer the NPDES program. In Washington, EPA has delegated authority for administering the NPDES program to Ecology. Ecology regulates stormwater discharges under individual NPDES permits, and a series of general permits: Phase I Municipal General Permit; Phase II Municipal General Permit; Industrial General Permit; Construction General Permit; Sand and Gravel General Permit; Boatyard General Permit; and Other General Permits (Hatchery, Water Treatment Plant, Concentrated Animal Feeding Operations, Fresh Fruit Packing). The State of Washington also regulates the discharge of wastewaters, including stormwater, to the ground under a State Waste Discharge Permit Program. Many of the NPDES general permits listed above are also State Waste Discharge General Permits... Groundwater Groundwater Quality Standards Groundwater quality in Washington State is protected by an anti-degradation policy such that existing and future beneficial uses of groundwater shall be maintained and protected. Drinking water quality is also regulated by the EPA. A summary of numerical criteria for selected contaminants is presented in Table.. Primary contaminants listed in Table. are known to have an adverse health effect at elevated levels. Secondary contaminants affect the aesthetic qualities related to public acceptance of drinking water 56. PROJECT NO JULY 8, 008

40 Table. Groundwater and Drinking Water Standards EPA Drinking Contaminant State Groundwater Quality Standard (WAC 7-00) Water MCL (EPA 86-F-0-0) or SMCL (40 CFR 4.) Primary Contaminants Units Barium* mg/l Cadmium* mg/l Chromium* mg/l Lead* # mg/l Mercury* mg/l Selenium* mg/l Fluoride 4 4 mg/l Nitrate (as N) 0 0 mg/l Total Coliform Bacteria <5%+ colony /00 ml Arsenic* μg/l Secondary Contaminants Copper* mg/l Iron* mg/l Manganese* mg/l Zinc* 5 5 mg/l Chloride mg/l Silver* mg/l Sulfate mg/l Total Dissolved Solids mg/l ph ph units * Metals are measured as total metals. # Indicates Action Level Columbia Valley/Kendall UGA Shallow groundwater and highly permeable soils in the Columbia Valley/Kendall UGA make groundwater resources susceptible to contamination. Critical Aquifer Recharge Areas are mapped as having moderate susceptibility in the northern portion of the Columbia Valley/Kendall UGA and high susceptibility in the southern portion. 57 Five Wellhead Protection Areas (WHPA) associated with source wells for EWSD #9 and WCWD # are located in the Columbia Valley/Kendall UGA. 58 Three of these wells have potential sources of contamination lying within the 6-month to 5-year time of travel (TOT) from the well (Table.). Potential sources of contamination within the WHPA for these wells consist of underground storage tanks (USTs) and discharges from two industries covered by the Industrial General NPDES Permit. No other potential sources of contamination in the Columbia Valley/Kendall UGA were found in Ecology s records of registered USTs, leaking USTs (LUSTs), or locations in the Confirmed or Suspected Contaminated Sites Listing (CSCL). 59 Drinking water quality has been evaluated in over 400 analyses for contaminants of concern from samples taken from EWSD#9 and WCWD #. Samples from WCWD PROJECT NO JULY 8, 008

41 # indicate no exceedances of drinking water standards. Results from EWSD#9 show two exceedances, one each for inorganic compounds and coliform bacteria. 60 Positive results for coliform are often short term and can be associated with water system infrastructure such as piping and storage facilities. Given the large sample set, these exceedances are not considered to be indicative of overall groundwater quality. Contaminants of concern commonly associated with on-site sewage systems (including community drainfields and private septic systems) are nitrates, phosphorus, fecal coliform, viruses, biochemical oxygen demand (BOD) and total suspended solids (TSS). 6 WCWD # provides the only sewer service in the Foothills Subarea. 6 Effluent from this system is discharged to a community drainfield located in the southwestern portion of the Columbia Valley/Kendall UGA. Assuming WCWD # provides sewer service to 47 existing water service connections 6, the remaining,04 dwellings in the Columbia Valley/Kendall UGA are assumed to be on septic systems. It is unclear how many, if any, recreational lots have individual septic systems. In properly functioning on-site sewage systems, constructed in adequate soils, and where groundwater is sufficiently deep, most contaminants of concern attenuate with distance from the application site. However, nitrogen commonly converts to nitrate in the vadose zone and can migrate into groundwater. In the Columbia Valley/Kendall UGA, background nitrate concentrations near the WCWD # community drainfield have been estimated to be 0.59 mg/l based on concentrations in the upgradient supply well. A recently installed monitoring well upgradient of the drainfield had nitrate concentrations of 0.89 mg/l in March 008 and 0.7 mg/l in April 008. Average nitrate concentrations down-gradient of the drainfield are similar, with the three downgradient monitoring wells averaging 0.8 mg/l for The highest average concentration of three downgradient monitoring wells was.0 mg/l and the maximum reported value was.7 mg/l. Limited data from elsewhere in the Columbia Valley/Kendall UGA suggest areas of elevated nitrates are present. The mean nitrate concentration from 05 water samples taken from EWSD#9 wells between 006 and 008 was 4. mg/l. 64 Rest of the Subarea Critical Aquifer Recharge Areas are mapped as having high susceptibility throughout most of the valley bottoms in the rest of the subarea. 65 Areas mapped as moderate susceptibility generally lie at higher elevations in the valley bottom. Nearly all of the population and drinking water sources are located in the areas of moderate to high susceptibility. Existing groundwater quality concerns are associated with areas having very high groundwater tables and areas where septic effluent rapidly infiltrates in high permeability soils. 66 Areas of very high groundwater tables (less than 5 feet below the surface) have not been specifically mapped, but may be considered high groundwater hazard areas. The rest of the subarea contains 4 WHPAs associated with water supply wells for Maple Falls Water Coop, Mount Baker School District in Deming and the North Fork Water System. Each WHPA has potential sources of contamination lying within 6 months to 5 years TOT (Table.). In addition, other potential sources of contamination not located 4 PROJECT NO JULY 8, 008

42 within WHPAs were identified by examining Ecology s records. In the rest of the subarea, there are 54 registered USTs, 5 leaking USTs (LUSTs), and no locations in the CSCS Listing 67. All dwellings in the rest of the subarea outside the Columbia Valley/Kendall UGA are served by private septic systems. Existing nitrate concentrations for groundwater were estimated from results of 475 water samples taken from water systems throughout the rest of the subarea from The mean nitrate concentration of these samples is.0 mg/l. Five water systems showed nitrate concentrations above the maximum contaminant level for drinking water (MCL) of 0 mg/l. The greatest nitrate concentration was mg/l. Of 57 samples that are above the MCL for nitrate, 5 are from three water systems, which are outside of the existing UGA. Coliform bacteria were detected times in samples from nine water systems in the rest of the subarea. Inorganic compounds exceeded drinking water standards five times for samples taken from three water systems. PROJECT NO JULY 8, 008 5

43 Table. Well Head Protection Areas Having Potential Sources of Contamination 69 System Name Source Name Evergreen Water-Sewer District #9 Whatcom County Water District # Maple FALLS Water Coop Source Susceptibility Rating Protection Type in Time of Travel (TOT) Columbia Valley/Kendall UGA Potential Contaminant Source Name Potential Contaminant Source Type Well # Moderate 6-Month Starvin Sams Mini Mart 5 Underground Storage Tank Well # Low 0-Year Starvin Sams Mini Mart 5 Underground Storage Tank Well # Low 0-Year Lehigh Northwest Cement Co Sumas Industrial NPDES Permit Well # Low 0-Year Lehigh Northwest Cement Co Sumas Underground Storage Tank Well # Moderate -Year Starvin Sams Mini Mart 5 Underground Storage Tank Well # Moderate 5-Year Whatcom Cnty Blue Bird Pit Industrial NPDES Permit Well # Moderate 5-Year Lehigh Northwest Cement Co Sumas Industrial NPDES Permit Well # Moderate 5-Year Lehigh Northwest Cement Co Sumas Underground Storage Tank Rest of the Subarea Well # Moderate 6-Month Maple Fuels Wash A Ton Underground Storage Tank Well # Moderate 6-Month Yorkston Oil Co Inc Underground Storage Tank Well # Moderate 6-Month Frosty Inn Underground Storage Tank Well # Moderate 6-Month Maple Falls Elementary School Underground Storage Tank Well # Moderate 6-Month Frosty Inn LUST Facility Well # Moderate 6-Month Maple Falls Elementary School Voluntary Cleanup Sites Well # Moderate 6-Month Maple Falls Elementary School State Cleanup Site Well # Moderate 5-Year Wa Dot Maple Falls Maint Facility Site Emergency/Haz Chem Rpt TIER Well # Moderate 5-Year Wa Dot Maple Falls Maint Facility Site Hazardous Waste Generator Well # Moderate 5-Year Wa Dot Maple Falls Maint Facility Site Underground Storage Tank Well # Unknown / High Assigned Maple Fuels Wash A Ton Underground Storage Tank Well # Unknown / High Assigned Yorkston Oil Co Inc Underground Storage Tank Well # Unknown / High Assigned Frosty Inn Underground Storage Tank Well # Unknown / High Assigned Maple Falls Elementary School State Cleanup Site Well # Unknown / High Assigned Maple Falls Elementary School Voluntary Cleanup Sites Well # Unknown / High Assigned Frosty Inn LUST Facility Well # Unknown / High Assigned Maple Falls Elementary School Underground Storage Tank North Fork Well Unknown / High Assigned Paisano Pizza Underground Storage Tank Water System Well Unknown / High Assigned Paisano Pizza LUST Facility Mount Baker School District- Deming Well # Low 5-Year Mt Baker School Dist 507 Hazardous Waste Generator. Public Stormwater Facilities Stormwater management in the Foothills Subarea is currently informal, with limited public stormwater infrastructure. There are no public flow control facilities (infiltration or 6 PROJECT NO JULY 8, 008

44 detention ponds) or runoff treatment facilities in the subarea. Whatcom County maintains a simple conveyance network along County roads throughout the subarea. The conveyance system typically consists of shallow, vegetated roadside ditches, and small approach and driveway cross culverts, with larger culverts crossing under the main road as necessary. The Washington State Department of Transportation (WSDOT) maintains a similar conveyance system along state highways. Two inventories of the public stormwater facilities within the Columbia Valley/Kendall UGA have been performed recently: Whatcom County inventoried stormwater conveyance features along County roads within the Paradise Lakes subdivision. 70 Aspect Consulting inventoried stormwater facilities for portions of State Route (SR) 54 (Mount Baker Highway) and SR 547 (Kendall Road) in May 008. Whatcom County s inventory identified 77 culverts in the County right-of-way in the Columbia Valley/Kendall UGA. These culverts are summarized in Table.4, and shown on Figure.6. The vast majority of culverts inventoried were -inch driveway cross culverts located in the Paradise Lakes subdivision. All but four culverts inventoried were in good condition. Three ditch sections were also inventoried by the County. Two of these ditches are located along Limestone Road at the northern boundary of the UGA, and the other ditch is located along Eason Road west of Kendall School near the southern boundary of the UGA. The culverts inventoried in the UGA were typically noted as flowing into and from road side ditches, although the ditch network within the residential subdivisions was not specifically inventoried. Drainage features located along private roadways, such as in the majority of the Paradise Lakes and Campers Paradise subdivisions, were also not inventoried. Table.4 Inventoried Culverts in the County Right-of-Way in the Columbia Valley/Kendall UGA Type of Culvert Diameter Size in Inches Number of Culverts Material Length Condition Driveway Cross Iron, HDPE, 8 6 Culvert Concrete 0 FT Good Driveway Cross Plastic, HDPE Culvert FT Good Driveway Cross CMP, Concrete, Culvert HDPE FT Good Driveway Cross Needs 4 Concrete, HDPE 0-5 FT Culvert Repair Driveway Cross Culvert 5 HDPE 0 FT Good Driveway Cross Culvert 8 HDPE 0 FT Good Driveway Cross Culvert 6 CMP 0 FT Good Storm Conveyance 6 Concrete, HDPE 6-0 FT Good PROJECT NO JULY 8, 008 7

45 Aspect Consulting s inventory identified eight culverts and three bridges in the WSDOT right-of-way. Culverts are listed in Table.5 and bridges in Table.6. There were very few culverts under or adjacent to the state highways in and around the Columbia Valley. Approach and driveway cross culverts were not common, and the three inventoried were either damaged or plugged. Two of the bridges spanned Kendall Creek and the third was located on SR 54 over an unnamed tributary to Kendall Creek. All three bridges were relatively low with.5 to.8 feet of freeboard between the top of the water surface to the bottom of the bridge beams on the day of the inventory. Table.5 Inventoried Culverts in the WSDOT Right-of-Way near the Columbia Valley UGA Culvert ID Material Diameter Size in Inches C HDPE C Concrete Type Length Longitude Latitude Driveway Cross Culvert SR 547 Culvert Flow Direction 0 FT South Condition Inlet almost completely plugged, outlet buried 40 FT West Good C Concrete C4 CMP C5 Concrete C6 Concrete C7 Concrete 8 C8 Plastic SR 547 Culvert Driveway Cross Culvert SR 547 Culvert SR 547 Culvert Approach Cross Culvert SR 547 Culvert 40 FT West Good 0 FT South Inlet crushed, outlet buried 40 FT West Good 40 FT West Good 0 FT South Inlet / plugged, outlet /4 plugged 60 FT North Good Table.6 Inventoried Bridges in the WSDOT Right-of-Way near the Columbia Valley Bridge ID Description Longitude Latitude Span in feet Height from Water Surface in feet BR SR 54 at Kendall Creek BR SR 54 at Kendall Creek tributary BR SR 547 at Kendall Creek PROJECT NO JULY 8, 008

46 The inventory also included catch basins and roadside ditches. There was a single catch basin identified. It is located in the WSDOT SR 547 right-of-way located near the entrance to Kendall Elementary. The catch basin collects road runoff and stormwater from culvert C8 and discharges it to the west, presumably to an outfall on the west side of Eason Road, although the outlet could not be located. Roadside ditches were also intermittent and, where present, were typically shallow and vegetated. The ditches appeared to be designed to collect and infiltrate road runoff rather than convey it any significant distance. PROJECT NO JULY 8, 008 9

47 Impacts. Water Quantity.. Surface Water Changes in land use have the potential to impact the quantity of surface water as streamflow and stormwater. Reduction in streamflow could result from development by increased surface water use and groundwater pumping from wells in hydraulic continuity with surface waters. As previously discussed, development of the natural landscape replaces native vegetation and soils with impervious areas as well as changes the pervious portions of the landscape. The impacts of these changes will be discussed in the stormwater section. An overview map of the Columbia Valley/Kendall UGA for Alternatives, and is provided on Figure.. Streamflow The criteria used for identifying significant impacts to streamflow are the MIFs established for the Foothill Subarea streams in WAC 7-50(see Table.). Any single or cumulative impact from the three land use Alternatives is considered significant if it may reduce streamflow below the MIF. The streams in the Foothills Subarea that are most important in terms of analyzing impacts are those with MIFs established and located near areas of proposed development. Flows in Kendall Creek have the most potential to be impacted by development under the alternatives because flows are already generally low, and the areas planned for higher development density are within the Kendall Creek watershed. Other streams that could be impacted include Maple Creek (adjacent to Maple Falls), and Gallop Creek (near Glacier). In addition, the North Fork and mainstem Nooksack Rivers could be influenced by development adjacent to the river or in tributary watersheds. Under WAC 7-50, Kendall Creek is closed year around to further consumptive appropriation, and Maple and Gallop Creeks are closed from July to October each year. The North Fork and mainstem Nooksack Rivers are not closed, however, any new consumptive water right would be subject to the MIF. Therefore, the most likely impact to streamflow from water use would occur through development of existing surface water or groundwater rights, or new exempt wells in hydraulic continuity with streams. Two existing water purveyors within the Columbia Valley/Kendall UGA have capacity for expansion. WCWD # and EWSD#9 are approved for an additional,047 connections, which is sufficient to serve the majority of future water demand under Alternatives,, or (see Table.6). The additional 00 connections (assumed to be residential) necessary under Alternative are anticipated to be granted to either WCWD # or EWSD#9 by DOH after infrastructure improvements and water conservation are implemented. Both purveyors use groundwater sources within the Columbia Valley, so 40 PROJECT NO JULY 8, 008

48 any increase in groundwater withdrawal could lead to a reduction in streamflow in Kendall Creek or another hydraulically connected water body. The existing consumptive water use in the Columbia Valley/Kendall UGA is 0 acrefeet per year (see Table.7). Under Alternatives,, and, the consumptive demand would increase to 404,, and 58 acre-feet per year, respectively (Table.6). In the regional context, the additional consumptive demand from the Alternatives is small (less than %) relative to the average volume of groundwater, and the average annual groundwater throughflow for the aquifer (see Section..). However, the withdrawals could be locally significant. Predicting the impact of increased groundwater withdrawals on streamflow in Kendall Creek is best addressed through the use of a numerical groundwater model such as MODFLOW. A groundwater model would evaluate the timing and magnitude of surface water/groundwater interactions in the Columbia Valley and determine if additional groundwater withdrawals under each Alternative would cause MIF violations in Kendall Creek. For example, if groundwater discharge to Kendall Creek was reduced in May through November, it could extend the period during which Kendall Creek runs dry and/or reduce flows below the MIF during these periods. Without such detailed study, the potential impact of additional groundwater withdrawals is assumed to be significant since Kendall Creek is known to be frequently below the MIF during the summer and fall, and any groundwater withdrawals during this time have the potential to either create or exacerbate a MIF violation. In other parts of the subarea, additional groundwater withdrawals are likely not going to cause significant impacts to streamflow for the following reasons: Streamflow in the North and Middle Forks is less dependent on groundwater than Kendall Creek. Additional consumptive demand will likely be distributed along the North Fork which has a large groundwater recharge area. The maximum consumptive use outside the Columbia Valley/Kendall UGA is 40 acre-feet under Alternative. This equates to 0.06 cfs which is likely not considered a measurable impact. Racehorse, Canyon, Bells, and Cornell Creek and the Middle Fork are located in areas zoned forestry (RF and CF) with no changes in land use designations proposed under the three Alternatives. 7 Stormwater Stormwater has the potential to impact surface water bodies by increasing peak flows, increasing the total volume of surface water runoff, and decreasing low flows by reducing groundwater recharge. The criteria used for identifying significant environmental impacts from stormwater are the flow control requirements in Ecology s Stormwater Management Manual 7 and Whatcom County s Development Standards. 7 Specifically, stormwater discharges are required not to exceed the pre-developed flow durations for the range of pre-developed discharge rates from 50 percent of the -year peak flow up to the full 50-year peak flow. In other words, stormwater discharges would cause a significant impact if they cause higher peak flows or a flashier response to storms. PROJECT NO JULY 8, 008 4

49 Without mitigation, stormwater volumes are expected to increase above this criterion under all three land use Alternatives. However, implementation of the stormwater BMPs outlined in Ecology s Stormwater Management Manual 74 and Whatcom County s Development Standards 75 such as infiltration of runoff should effectively mitigate these impacts in the entire Foothills Subarea, including the Columbia Valley/Kendall UGA (see Section 4). As with the evaluation of existing stormwater quantities, a hydrologic model (WWHM) was used to simulate the annual water balance in the Columbia Valley/Kendall UGA for each Alternative, using the method described in Section... As a possible mitigation measure (see Section 4), Alternatives and were also evaluated assuming relatively aggressive implementation of LID strategies. A breakdown of the zoning under each alternative is shown in Table.. This breakdown forms the basis of the land use assumptions used in the hydrologic model. Table. Modeled Land Use for Columbia Valley/Kendall UGA Study Area (all values in acres) Scenario Alternative Alternative Alternative Paradise Lakes, Peaceful Valley Campers Paradise Residential UR 4 Other Residential RR Paradise Lakes, Peaceful Valley Campers Paradise Residential R5-R0 Developed and Undeveloped Kendall STC Commercial Industrial Forestry Proposed Commercial Proposed LII Rural Forestry Total Each area was converted to impervious and pervious areas using the following assumptions: For Alternative : The 700 acres of existing platted land was assumed to be built out to the maximum density possible with the infill of all existing undeveloped lots. There are 8 existing lots available for development in the Paradise Lakes and Peaceful Valley subdivisions. 76 Therefore the maximum density for these developments would be,989 lots, or.8 units per acre. 77 For the area at this density, 6%, 6% and % were assigned to impervious roads 78, roofs 79, and driveways 80, respectively. This area was assigned an EIA factor of The pervious portion was classified as grasscovered outwash soils. The remaining undeveloped area zoned for 4 DU/acre under Alternative (55 acres) was assumed to be utilized for the remaining new dwelling units in the Columbia Valley/Kendall UGA. This density of.7 DU/acre corresponds to 0%, 4% and % and 5% of the land area to impervious roads 8, roofs 8, driveways 84, and stormwater ponds 85 respectively. This area was assigned an EIA factor of The pervious area was classified as grass-covered outwash soils. 4 PROJECT NO JULY 8, 008

50 85 acres for the existing 4 acre Kendall Small Town Center and 44 acres of the proposed town center were assumed to be 90% impervious 87 and 0% grass-covered outwash, with an EIA factor of acres zoned Light Impact Industrial (LII) were assumed to contain a maximum of 4.6 impervious acres 88 and 5.4 acres of grass covered outwash, with an EIA factor of acres zoned R-5 and R-0 near Kendall were assumed to be 0% impervious divided between roads (7%), roofs (.5%) and driveways (.5%), with an EIA factor of The pervious area around Kendall was classified as grass-covered outwash. This area is unaffected by Alternative zoning. The balance of the study area (40 acres) was modeled as outwash forest. This area corresponds to the 40 acre parcel to the north of Limestone Road that may be considered for potential planned LII.. For Alternative : The existing 700 acres of existing platted land to be the same as in Alternative. The remaining undeveloped area zoned for 4 DU/acre development under Alternative (59 acres) was assumed to be utilized for the remaining new dwelling units in the Columbia Valley/Kendall UGA. This density of 0.8 DU/acre corresponds to 6%, % and % and % of the land area to impervious roads 90, roofs 9, driveways 9, and stormwater ponds 9 respectively. This area was assigned an EIA factor of The pervious area was classified as grass-covered outwash soils. 4 acres for the existing Kendall Small Town Center was assumed to be 90% impervious, 95 with an EIA factor of.0, and 0 % grass-covered outwash. 40 acres zoned Light Impact Industrial (LII) were assumed to contain a maximum of 4.6 impervious acres 96 and 5.4 acres of grass covered outwash, with an EIA factor of acres zoned R-5 and R-0 near Kendall were assumed to be 0% impervious divided between roads (7%), roofs (.5%) and driveways (.5%), with an EIA factor of The pervious area around Kendall was classified as grass-covered outwash. The balance of the study area (80 acres) was modeled as outwash forest. This area corresponds to the 40 acre parcel to the north of Limestone Road that may be considered for potential planned LII, and 40 acres of RF in the eastern portion of the study area. For Alternative : The existing 700 acres of existing platted land to be the same as in Alternative. The remaining undeveloped area previously zoned for 4 DU/acre development will be re-zoned as R5 or R0. For the purposes of this analysis, these 65 acres were assumed to be utilized for the remaining new dwelling units in the Columbia Valley/Kendall UGA. This density of 0. DU/acre corresponds to approximately %, % and % and % of the land area to impervious roads, roofs, driveways, and PROJECT NO JULY 8, 008 4

51 stormwater ponds respectively, with an EIA factor of The pervious area portion of this area was classified as grass-covered outwash. For the 4 acres of the existing Kendall Small Town, 8.9 acres were modeled as impervious 99 and the remaining 5. acres outwash grass with an EIA factor of.0,. The balance of the study area (00 acres) was modeled as outwash forest. This area corresponds to 80 acres to the north of Limestone Road, and 0 acres of RF in the eastern portion of the study area. A summary of acres in each land use zoning classification in the Columbia Valley/Kendall UGA study area (,59 acres) is provided in Table.. Both Alternatives and were also simulated assuming all new development would implement aggressive LID strategies (see Section 4). Changes made to the land use classifications are outlined below: Areas of proposed residential development were modeled with a 9%, 50%, and 80% reduction of the land area for impervious roads, 00, driveways, 0 and stormwater ponds, 0 respectively, and an EIA factor of The pervious area was classified as 4% grass-covered outwash 04 and 0% forested outwash. 05 Areas of proposed commercial and industrial development were assigned an EIA factor of Alternative would create the most new impervious area as either TIA or EIA. A summary of the impervious areas resulting from each Alternative is shown in Table.. Table. Impervious Areas for Columbia Valley/Kendall UGA Total Impervious Area (TIA) in Acres Effective Impervious Area (EIA) in Acres Existing Condition Alternative Alternative 7 9 Alternative 6 6 Alternative LID 58 4 Alternative LID 9 8 Implementing aggressive LID strategies (see Section 4), would still result in a significant amount of new TIA, but would dramatically reduce the amount of new EIA. The detailed land use classifications used for each scenario in the WWHM model are presented in Table.. The total area under each scenario is 59 acres. Note that stormwater ponds are typically considered impervious for predicting runoff. There are no existing stormwater ponds in the Columbia Valley. 44 PROJECT NO JULY 8, 008

52 Table. Land Use Classifications for Existing Conditions and Alternatives Runoff Modeling Land Use Classifications Effective Impervious Areas in Acres Pervious Areas in Acres Roads Stormwater Ponds Driveways Roofs Outwash Grass Outwash Forest Existing Condition Alternative Alternative Alternative Alternative LID Alternative LID Development typically causes a decrease in evapotranspiration (through the removal of vegetation) and groundwater recharge (by covering pervious areas with impervious surfaces) and by decreasing infiltration capacity of disturbed pervious areas. These actions result in a corresponding increase in stormwater runoff. WWHM was used to predict the magnitude of these changes in surface runoff, evapotranspiration and groundwater recharge under the different Alternatives. Annual averages for each of these water balance components are summarized in Table.4. As anticipated, each Alternative results in an increase in surface water runoff and decreases in evapotranspiration. Stormwater runoff increases the most in Alternatives and, with a 78% and 9% increase in the annual runoff volume, respectively. Aggressively implementing LID for these Alternatives could reduce the increase in runoff to 7% and % percent of the existing runoff volume, respectively. Alternative would result in a % increase over existing conditions. The increase in runoff from any of the Alternatives can also be compared in the watershed context. Runoff from the entire Kendall Creek Watershed (5,60 acres) is estimated at approximately 0,000 acre-feet per year (see Table.). By comparison, the increase in runoff under Alternatives and is,064 and 548 acre-feet, respectively, representing a change of.7% to 5.% for the watershed. PROJECT NO JULY 8,

53 Table.4 WWHM Simulated Annual Water Balance for the Columbia Valley/Kendall UGA 07 Water Balance Components in Inches Per Year Scenario Runoff Evapotranspiration Groundwater Recharge Existing Condition Alternative Alternative Alternative Alternative LID Alternative LID Change Over Existing Condition in Acre-Feet Per Year Runoff Evapotranspiration Groundwater Recharge Alternative, Alternative Alternative Alternative LID Alternative LID The ultimate fate of runoff depends on stormwater management practices in the area. If traditional conveyance and detention systems are used, the stormwater system would be connected to surface water bodies and would cause an increase in flow in Kendall Creek during the wet season. However, if infiltration is used, either through traditional infiltration ponds or LID practices, the stormwater runoff would be conveyed to the ground and would increase groundwater recharge (Table.5). Given the porous outwash soils in the area, it is likely that infiltration practices would be favorable for cost and environmental reasons. If 00 percent infiltration is used for new development, the annual water balance for the Columbia Valley/Kendall UGA would be as shown in Table.5. Runoff from existing development would continue unchanged. However, all stormwater from new development would be infiltrated. In Alternatives through, this would involve a conventional stormwater conveyance system (i.e., roadside ditches or catchbasins and pipes) leading to infiltration ponds or trenches. For the LID alternatives this would involve ) generating less stormwater by reducing impervious areas, ) increasing evapotranspiration through use of rain gardens and other vegetated BMPs, and/or ) locating smaller infiltration facilities through out the development. 46 PROJECT NO JULY 8, 008

54 Table.5 WWHM Simulated Annual Water Balance assuming 00% infiltration of new runoff Water Balance Components in Inches Per Year Increase in Groundwater Recharge over Existing Condition in Runoff Evapotranspiration Groundwater Recharge Acre Feet per Year Existing Condition n/a Alternative Alternative Alternative Alternative LID Alternative LID Groundwater Groundwater quantity has the potential to be impacted in two primary ways: increased stormwater runoff if not infiltrated, could lead to decreased recharge to aquifers, and increased groundwater use could deplete groundwater resources. The groundwater quantity impacts in the rest of the subarea are limited to increased groundwater use. The criterion used for identifying significant impacts to groundwater quantity is if the cumulative impact of reduced groundwater recharge and increased consumptive groundwater use results in a net decrease in the existing annual groundwater volume. Columbia Valley/Kendall UGA The annual water balance presented in Section.. indicates that development and subsequent increase in runoff, if not infiltrated, could reduce recharge in the Columbia Valley/Kendall UGA by greater than,000 acre-feet per year under Alternative and over 500 acre feet under Alternative (see Table.4). This loss of recharge represents a 0 to 0 percent reduction in recharge that occurs in the existing condition in the Columbia Valley/Kendall UGA. These impacts under Alternatives and are considered significant. Under Alternative, an increase in recharge is expected to occur because a large number of acres of existing forest could be converted into R5 or R0 development which would decrease evapotranspiration without increasing runoff, resulting in a net gain in annual recharge. There are currently,047 additional approved connections between EWSD#9 and WCWD # (see Table.6). The number of currently approved connections for these water systems will not accommodate anticipated growth under Alternative (expected to be,47 new dwellings). DOH sets the number of approved connections based on criteria that include system capacity and water rights. The number of approved connections might be increased in the future, if it can be demonstrated to DOH that conservation and system improvements lead to a reduced ADD. Up to 500 connections are anticipated to be approved through water conservation and system improvements, meaning sufficient connections are likely available to accommodate future demand under Alternatives,, and. PROJECT NO JULY 8,

55 Groundwater use associated with Alternatives, and was estimated using the same methods as the existing condition (see Section..). However, the ADD used to estimate water use under the future development scenarios was revised to reflect a lower estimate based on anticipated infrastructure improvements that will result in system-wide water conservation in WCWD #. The improvements are anticipated to reduce the ADD for the WCWD # from 60 gpd to gpd. 08 The future ADD for EWSD#9 was estimated to be 00 gpd. 09 A weighted average was calculated for the additional dwellings under each alternative assuming 56 of the new connections came from EWSD#9 (See Table.6) and the remaining connections were served by WCWD #. Weighted averages were calculated for return flow in a similar manner, assuming household use remains the same in the future as in the existing condition (see Section..). The balance was considered consumptive use in the Columbia Valley/Kendall UGA for each of the Alternatives. The results of the analysis indicate that consumptive water use could increase up to 0 acre-feet per year under Alternative and acre-feet per year under Alternative. These increases represent 5 and percent of recharge for those Alternatives, respectively. The impact from consumptive water use under Alternatives and are considered significant. Under Alternative, the additional consumptive use is 57 acre-feet per year. However, groundwater recharge increases 09 acre-feet per year over the existing condition (see Table.4) for a net gain of 5 acre-feet per year, thus there is no significant impact to groundwater quantity under Alternative. Table.6 Existing and Future Water Use in the Columbia Valley/Kendall UGA Water Volume in Acre Feet per Year Total Number of Dwellings Number of Non- Residential PWS Connections Number of PWS Connections Total Water Use Total Return Flow Total Consumptive Water Use Additional Consumptive Demand over Existing condition Existing Condition,8, n/a Alternative,58, Alternative,09, Alternative,766, The unmitigated cumulative impact of decreased recharge and increased consumptive water use could result in a net loss of 799 and 4 acre-feet of water per year to the aquifer under Alternatives and, respectively (See Tables.6 and.4). 0 These cumulative impacts are considered significant. Within the WCWD # service area, a groundwater bypass reach is created between the water supply wells and drainfield area (Figure.). Groundwater extracted from the water supply well is returned to the drainfield approximately,000 feet downgradient of PW- and about 500 feet from PW-. The maximum quantity that will bypass this reach is 50 acre-feet/year under Alternative. Groundwater flow through this area is 48 PROJECT NO JULY 8, 008

56 estimated at 5,50 acre-feet annually. The maximum impact to groundwater flow through this reach is, therefore, about 9% of the total flow-through. As no known surface water or wetland features or private wells are present between the supply wells and the drainfield, this impact to groundwater is not considered significant. Rest of the Subarea The number of currently approved connections is more than adequate to accommodate anticipated growth under Alternatives through in specific small towns, such as Glacier and Maple Falls. An exception is Deming, which is anticipated to experience modest growth under all three alternatives but does not currently possess any approved additional connections (see Table.6). Increased groundwater use associated with Alternatives through in the rest of the subarea was estimated using the same criteria as existing conditions (see Section..). Additional assumptions used to project water used for the three Alternatives were: The existing proportions of year-round and seasonal/unoccupied dwellings will remain the same into the future for Glacier, Maple Falls, Deming and the remaining subarea. The existing ratios of assumed residents per dwelling unit remained the same into the future for Glacier, Maple Falls, Deming and the remaining subarea. The number of non-residential PWS connections did not change in the future. The results of the analysis indicate that consumptive water use could increase 7, 7 and 5 acre-feet per year under Alternatives, and, respectively. Groundwater in the upper Valley aquifer in the Maple Falls and Glacier areas discharges to the Nooksack River. Conservatively assuming that the combined impact from consumptive use of groundwater under Alternative (7 acre-feet) all discharges to the North Fork of Nooksack, this equates to 0.04 cfs or 0.0% of the lowest 90% flow on the North Fork of the Nooksack at Glacier. This magnitude of impact is likely not measurable and is not considered significant. Table.7 Existing and Future Water Use in the Rest of the Subarea Water Volume in Acre Feet per Year Location Number of Year - Round Dwellings Number of Seasonal/ Unoccupied Dwellings Number of Non- Residential PWS Connections Total Water Use Total Return Flow Total Consumptive Water Use Additional Consumptive Demand over Existing condition Existing Condition,09 994, n/a Alternative,088,055, Alternative,54,045, Alternative,094,0, PROJECT NO JULY 8,

57 . Water Quality.. Surface Water Development in the Foothills Subarea has the potential to impact surface water quality through several different mechanisms: Clearing of forested areas and riparian vegetation, Stormwater discharges from residential and commercial development, Stormwater and waste discharges from industrial areas, Waste discharges from sewage treatment, and Reduction in summer low flows from increased groundwater withdrawals and faster stormwater delivery to streams. These mechanisms were evaluated for their potential to cause significant impacts under each of the Alternatives. The criteria used for identifying significant impact to surface water quality were the state surface water quality standards set forth in WAC-7-0A (see Section..). Clearing of Vegetation Clearing of vegetation can cause water quality problems with temperature and sediment. The existing issues with elevated water temperature are thought to be caused by forestry practices, although similar effects can result from urbanization or other land uses that reduce riparian and upland vegetation. Alternative has essentially the same amount of land zoned for forestry (RF and CF) as the existing condition (Alternative ) and Alternative. Therefore, there would not be an increased impact to water temperature from forestry under any of the alternatives. Urbanization and development near sensitive streams could impact temperature by removing canopy cover along main stream reaches and tributaries. The streams of most concern for water temperature impacts are the impaired streams in areas of most intense planned development. Kendall Creek in the Columbia Valley/Kendall UGA, Maple Creek near Maple Falls, and the Glen and Maple Falls and Gallop Creek near Glacier all have the potential to be impacted with elevated water temperatures from development. The other 0(d) listed streams are in areas where the land classifications for all three Alternatives are the same (mostly RF and R5 or R0 zoning). Protection of native riparian vegetation is an effective means to reduce the potential impact of development on water temperature. Protective buffers have been established in (WCC 6.6) to prevent removal of riparian vegetation. The buffers vary from 50 feet (non-fish bearing streams) to 00 feet (fish bearing streams) and 50 feet for shorelines. These buffers may be increased by the County. 50 PROJECT NO JULY 8, 008

58 Stormwater Discharges from Residential, Commercial and Industrial Development The most significant source of surface water quality impacts in the Foothills Subarea is increased stormwater runoff to sensitive receiving waters. As documented in Section.., increased development under all three Alternatives would increase the volume of stormwater generated. Stormwater has the potential to become contaminated as it contacts pollution generating surfaces such as roads, parking lots, graveled areas, bare soils, or landscaped areas. Runoff from roads can add oil, grease, sediment, and heavy metals such as lead and cadmium among other pollutants to stormwater. Roofs and sidewalks generally do not impact pollutant loads. Landscaped areas can contribute pesticides, herbicides and animal waste to runoff. Finally, suspended solids and nutrients, particularly phosphorus, can have detrimental impacts to sensitive lakes (e.g., Kendall, Sprague, and Silver Lakes). Under Alternative, runoff from planned industrial and commercial areas can also contribute additional pollutants to surface runoff. One of the permitted uses under Small Town Commercial District (WCC0.6) and General Commercial District zoning (WCC 0.6) is vehicle service, repair, and washing which if improperly managed could lead to additional stormwater contamination. Light Impact Industrial zoning (WCC 0.66) includes a range of permitted uses including general manufacturing and fabrication as well as solid waste handling facilities. Depending on the particular use, pollutants like heavy metals, PCBs, acids, solvents, or other toxic chemicals may also be introduced into runoff. Other pollutants may also impact streams directly as a result of development. Impacts to dissolved oxygen levels, as they relate to water temperature, and sediments should be minimal for the same reasons discussed regarding temperature. Protective buffers will also minimize stream erosion that might otherwise occur. Sewage Treatment Plant and Industrial Waste Discharges Direct discharge of industrial waste or sewage treatment plant effluent to surface water has the potential to impact surface water quantity. These discharges would be regulated under the Clean Water Act, and Washington s Water Pollution Control Law (RCW 90.48). In addition, these discharges would require NPDES or state waste discharge permits that set effluent limits and require use of BMPs to control pollution. In the Columbia Valley/Kendall UGA, it is unlikely that surface water discharges from sewage treatment plants or industrial facilities would occur under any Alternative. The existing WCWD # treatment system uses a septic field to discharge treated effluent to ground. Alternative includes 40 to 80 acres that potentially could be zoned for LII development, but the industrial areas are located far from any surface water bodies so a surface water discharge is unlikely. Reduction in Summer Low Flows Increased groundwater withdrawals for water supply, combined with decreased groundwater recharge from development have the potential to reduce surface water flow, particularly during the dry period. Lower flows can cause an increase in water temperature as slower flow has a longer period of exposure to solar radiation. In turn, PROJECT NO JULY 8, 008 5

59 higher temperatures can cause a reduction in dissolved oxygen concentrations. However, the magnitude of the increase in groundwater withdrawals is unlikely to cause a change in stream velocities sufficient to cause a significant impact to stream temperature or dissolved oxygen concentration in a majority of subarea streams. Kendall Creek, however, is the exception. As noted in Section.., predicting the impact of increased groundwater withdrawals on streamflow in Kendall Creek is difficult without a quantitative groundwater model to evaluate the timing of surface water/groundwater interactions in the Columbia Valley. Without such information to assess the streamflow impacts, associated water quality impacts also cannot be determined... Groundwater Development in the Foothills Subarea has the potential to impact groundwater quality through several different mechanisms: Stormwater discharges to groundwater through infiltration from residential and commercial development, Stormwater and waste discharges to groundwater through infiltration from industrial areas, and Waste discharges from on-site sewage treatment including individual septic and community drainfields. These mechanisms were evaluated for their potential to cause significant impacts under each of the Alternatives. The criteria used for identifying significant impact to groundwater quality were the state groundwater quality standards set forth in WAC-7-00 and EPA s federal drinking water regulations (see Section..). Infiltration of Stormwater from Residential, Commercial and Industrial Development Groundwater quality can be impaired by infiltrating contaminated runoff without proper treatment. Contaminants from residential and commercial development could include oil, grease, sediment, heavy metals such as lead and cadmium, pesticides, and herbicides. Contaminants from industrial development could include additional contaminants such as PCBs, acids, solvents, or other hazardous substances. Discharges from On-Site Sewage Treatment Under Alternatives and, the majority of growth in the Columbia Valley/Kendall UGA will be accommodated by the WCWD # sewage treatment plant and community drainfield. The nitrate concentration resulting from this increase in septic discharge has been previously estimated at. mg/l at the downgradient portion of the development or an increase of.86 mg/l over an assumed background concentration of 0.5 mg/l. 4 The relatively small increase in predicted nitrate concentrations relative to the large number of new connections results from planned upgrades to the sewage treatment system that will reduce nitrate loading from 5 mg/l nitrate-n to 9 mg/l. The total number of new dwellings under Alternative is,47. As of July, 006 there were approximately 98 vacant and re-developable lots in the Paradise Lakes subdivision 5 PROJECT NO JULY 8, 008

60 that would likely require on-site septic systems. These lots are located in two geographically distinct areas (northerly and southerly) of the Paradise Lakes subdivision (Figure.6). The balance of the new dwellings under Alternative (i.e., 849), we assume would be constructed within the Whatcom County water district sewer area and would be connected to the District s sanitary system. Other than the lots at Paradise Lakes, zoning regulations would not permit un-sewered dwelling at a density of more than one dwelling unit per 5 acres. The potential 98 unsewered dwellings in Paradise Lakes will result in additional nitrate loading to the aquifer. Build out of these lots is assumed to occur under Alternatives,, and. The nitrate loading to groundwater from the two Paradise Lakes subdivisions is not expected to be cumulative between the two portions of the subdivision. Of the 98 undeveloped lots that would likely have on-site drainfields, 7 are located in Paradise Divisions -6 (southerly portion of Paradise Lakes subdivision shown on Figure.6) and 8 are located in Paradise Divisions 7-8 (northerly portion of Paradise Lakes subdivision shown on Figure.6). Groundwater passing beneath the northerly subdivision discharges to Kendall and Sprague Lakes, so nitrate loading to groundwater from the northerly Paradise Lakes subdivision is not expected to be cumulative with nitrate loading from the southern Paradise Lakes area. The Ecology nitrate loading model was applied to estimate nitrate loading from the additional non-sewered dwellings in the northern and southern portions of the Paradise Lakes subdivisions. The model incorporates site-specific hydrogeologic conditions to dilute drainfield effluent with precipitation infiltrating through the drainfield and groundwater flowing beneath the drainfield. Model input parameters are presented in Table.8. The model is based on the following data and assumptions: 7 dwellings in the southern portion and 8 dwellings in the northern portion with an average drainfield size of,000 square feet (total drainfield areas of 7,000 and 8,000 for the northern and southern subdivisions, respectively) Precipitation Recharge of 4.0, 7., and 9.4 inches for Alternatives,, and, respectively (see Table.. 4) Nitrate-N in precipitation of 0.4 mg/l (Ecology default value) 60 mg/l nitrate-n loading (Ecology default value) 500 feet/day aquifer hydraulic conductivity and groundwater gradient of 0.00 ft/ft Aquifer width of,444 ft for southern subdivision and,666 ft for northern subdivision(widest portion of subdivision perpendicular to groundwater flow 0% denitrification in subsurface (Ecology default value) 0-foot depth of mixing in aquifer (Ecology default value) Flow per household gpd (Ecology default value) Background nitrate-n of 0.4. mg/l (average value from Evergreen SWD 9 wells) Results of the analysis for the southern Paradise Lakes subdivision indicate an increase in nitrate-n of about.5 mg/l and a total predicted concentration of 5.6 mg/l for all PROJECT NO JULY 8, 008 5

61 three Alternatives (Table.8). For the northern portion of the subdivision, nitrate levels are expected to increase to. mg/l to a total predicted nitrate concentration of 6. mg/l, for all three Alternatives. Ecology s Groundwater Quality Criteria (WAC 7-00) contains an antidegradation policy to groundwater quality that may be better than the State water quality standards. In the case of on-site sewage systems, Ecology has determined that the combination of treatment and housing density must result in a maximum increase of mg/l nitrate-n increase over background conditions, and also cannot exceed the state criteria of 0 mg/l. The estimated nitrate loading from Paradise Lakes subdivisions (increases of.5 mg/l and. mg/l) and for the WCWD # drainfield (.86 mg/l increase) are close to the acceptable State water quality increase of mg/l and are considered a potential impact under Alternatives,, and. In the rest of the subarea, future growth under each Alternative will be served by private septic systems. Zoning in the remaining areas ranges from dwellings/acre to dwelling per 0 acres. The Ecology nitrate loading model was run for the maximum density of DU/acre assuming the same aquifer characteristics as the Columbia Valley/Kendall UGA for a generic, stand-alone, acre parcel. Results indicate less than mg/l nitrate increases; however, the final layout of adjoining parcels and site specific aquifer characteristics will effect the predicted nitrate concentrations and significant changes in nitrate loading (i.e., greater than mg/l) cannot be ruled out (Table.8). More specific data on build out scenarios and aquifer characteristics would be necessary to assess area specific nitrate loading. 54 PROJECT NO JULY 8, 008

62 Table.8 Nitrate Loading Analysis Symbol Description units Alternative () Paradise Div -6 (south part of PD) Paradise Div 7-8 (north part of PD) DU/AC Density () Ad Area of drainfield ft 7,000 8,000,000 R Precipitation recharge in/yr Vr Volume rate of Precipitation Recharge gpd Nr Nitrogen concentration in precipitation mg/l d Denitrification rate in aquifer 0% 0% 0% n Number of homes 7 8 w Septic waste generated per household gpd Vw Volume rate of septic waste discharge gpd, 0,45 9 Ns Nitrate concentration in septic waste inflows mg/l D Denitrification rate in septic system 0% 0% 0% Nw Nitrate concentration in septic waste discharge mg/l V Total infiltration from drainfield area gpd 0,04 0, N Total nitrogen concentration from drainfield area mg/l K Hydraulic conductivity of aquifer ft/d i Hydraulic gradient of aquifer ft/ft b Thickness of mixing zone in aquifer ft Wa Width of aquifer that mixes with drainfield ft,444, Q Aquifer discharge gpd 40,85 48,77,949 Nb Nitrate concentration - background mg/l Ngw Downgradient nitrate concentration in the aquifer mg/l Increase over background mg/l () The model parameters and results are only shown for Alternative. The results for Alternatives and are the same as Alternative. () Model shows expected loading for a single, generic -acre parcel. Final configuration of lots may lead to higher nitrate loading. Precipitation recharge from Utah State University, 00a, p. 0.. Public Stormwater Facilities Public stormwater facilities in the Foothills Subarea are currently limited to conveyances along public rights-of-way. These facilities appear to function adequately for conveying, and/or infiltrating stormwater flows under existing conditions. The development that would occur under all Alternatives is primarily located on private property and would require development of private stormwater facilities. Private development could impact public stormwater facilities either by discharging to a public stormwater conveyance system with inadequate capacity, or by discharging to a stream such that flows increase sufficiently to require changing the capacity of a public bridge or culvert. These impacts are unlikely to occur in the Columbia Valley/Kendall UGA because the coarse outwash will favor infiltration for stormwater management, and stormwater management regulations hold developers responsible for not increasing peak flows or negatively impacting downstream conveyances. PROJECT NO JULY 8,

63 No new public facilities are anticipated to be required under any of the Alternatives. No significant impacts to public stormwater facilities are anticipated under any of the Alternatives. 56 PROJECT NO JULY 8, 008

64 4 Potential Mitigation 4. Alternative 4.. Water Quantity Four potentially significant impacts to water quantity under Alternative were identified in Sections.. and..: Increased stormwater runoff, Decreased groundwater recharge, Increased groundwater withdrawals for water supply, and Decreased flows in Kendall Creek due to additional groundwater withdrawals. Increased Stormwater Runoff Mitigation for increased stormwater runoff can be achieved by complying with the flow control standards in the Ecology Stormwater Manual 4 and Whatcom County Development Standards. 5 This requires implementing BMPs for flow control. Flow control BMPs are designed to control the rate, frequency, and flow duration of stormwater runoff. Flow control BMPs includes detention ponds, infiltration or retention ponds, or LID practices. Implementing LID strategies can be very effective in reducing the overall impact of new development under Alternative. Not only does LID reduce the volume of stormwater runoff that needs to be managed, it also maintains a more natural groundwater recharge pattern in areas with permeable soils, like the Columbia Valley/Kendall UGA. By infiltrating near the source of runoff generation, LID also reduces the potential for runoff to become polluted. Possible LID strategies that could be implemented in the Foothills Subarea are outlined below: 6 LID strategies for Residential Development 00 percent dispersion and infiltration of roof runoff, Hybrid or open space road layout which combine the traffic advantages of typical grid road layouts with the reduced impervious area and site disturbance characteristics of a typical curvilinear (cul-de-sac) road layout, Alternative turnaround designs such as smaller radius cul-de-sacs, cul-de-sacs with bioretention in the center, or hammerhead turnarounds, Retain native vegetation as open space, Reduce development footprint, Permeable paving for driveways, PROJECT NO JULY 8,

65 Bioretention (rain garden) areas in development layout, and Reverse slope sidewalks. LID strategies for Commercial and Industrial Development Retain native vegetation as open space, Use permeable paving for parking lots, and Rainwater harvesting for landscape irrigation water. Selecting infiltration and/or LID BMPs to meet the runoff control requirement could effectively mitigate the reduction in recharge, particularly in Critical Aquifer Recharge Areas. In fact, infiltrating 00 percent of runoff would increase groundwater recharge relative to existing conditions, particularly in the Columbia Valley/Kendall Area. This has the additional advantage of offsetting increased water use and helping maintain flows in Kendall Creek during the dry season. Special consideration would have to be made for infiltration in potential high groundwater hazard areas such that infiltration would not cause any adverse impacts such as flooding crawlspaces and basements of homes. Decreased Groundwater Recharge and Increased Groundwater Use Mitigation for decreased groundwater recharge and increased groundwater use in the Columbia Valley/Kendall UGA can be achieved using infiltration for the BMP for flow control. If 00 percent of stormwater generated under Alternative is infiltrated, the net increase in groundwater recharge (467 acre-feet per year, see Table.5),would exceed the impact to groundwater quantity from increased water use (0 acre feet per year, see Table.6). This mitigation option would be most effective if LID practices are used or multiple infiltration ponds were constructed to accommodate runoff throughout the area rather than infiltrating in a single pond. Decreased Flows in Kendall Creek Although infiltration would mitigate the cumulative impacts of development to groundwater quantity on an annual basis, the timing of groundwater discharges to Kendall Creek is important. Stormwater would recharge groundwater in winter, but would do little to offset water use in summer, the period of peak demand. If groundwater discharge to Kendall Creek is reduced in May through November, it could extend the period during which Kendall Creek runs dry and/or reduce flows below the MIF. A numerical groundwater model could be used to identify if and when significant impacts to water quantity in Kendall Creek would occur. The groundwater model could also be used to determine if it is feasible to mitigate for any potential impact through strategically placed and designed infiltration ponds. Using the groundwater model to determine the spatial relationship and timing of recharge from these facilities could be effective for identifying mitigation to maintain natural flow in Kendall Creek. 58 PROJECT NO JULY 8, 008

66 4.. Water Quality Significant environmental impacts to surface water quality under Alternative were identified in Section.. as: Increases in stream water temperatures and sediment loads from removal of riparian vegetation, Increases in stormwater pollutant loads that may discharge to streams and groundwater through infiltration, Increases in stream water temperature in Kendall Creek due to reduced baseflows from groundwater withdrawals, Significant environmental impacts to groundwater quality under Alternative were identified in Section.. as: Infiltration of contaminated stormwater with pollutant loads, and Nitrate loading from additional septic systems discharges in the Columbia Valley/Kendall UGA. Increased Stream Temperature and Sediment Load from Clearing Impacts to stream temperatures and sediment loads can be effectively mitigated by following the protective buffers designated by WCC 6.6. For maximum effectiveness, the protective buffers could be applied to all ephemeral, intermittent and perennial tributaries to rivers and streams. Additionally, riparian plantings could be implemented in areas where buffers are not currently met along sensitive streams. Stormwater Pollutants Impacts related to stormwater can be effectively mitigated by implementing LID strategies and the runoff treatment and source control BMPs outlined in the Ecology Manual. 7 BMPs identified in the Ecology Manual that mitigate for the water quality impacts of increased stormwater flows include source control and runoff treatment. The intent of source control BMPs is to prevent stormwater from becoming contaminated by reducing exposure of pollutants. Runoff treatment BMPs are designed to remove pollutants by gravity settling, filtration, biological uptake and/or soil adsorption. Many of the LID strategies listed in Section 4.. have the multiple benefits by reducing runoff volume, limiting stormwater pollution by preventing commingling of clean and contaminated stormwater, and providing runoff treatment. Compliance with Ecology s Stormwater Manual 8 and Whatcom County Development Standards 9 for runoff treatment could effectively mitigate surface and groundwater pollution related to stormwater. To protect sensitive lakes, the phosphorus treatment BMPs from the Ecology Stormwater Manual 0 should be considered for facilities that discharge stormwater to either surface water or groundwater within ¼ mile of a lake. Enhanced stormwater treatment should also be considered prior to infiltration within a Critical Aquifer Recharge area. PROJECT NO JULY 8,

67 Increased Temperature in Kendall Creek from Groundwater Use As discussed in Section 4.., additional groundwater withdrawals in the Columbia Valley/Kendall UGA have the potential to decrease streamflow in Kendall Creek. Water temperature is highly dependent on streamflow so the nature of impacts on water temperature cannot be sufficiently evaluated without knowing the nature of impacts to streamflow in Kendall Creek. This would be based on the specific timing for surface water/groundwater interactions in the watershed determined by a numerical groundwater model. Using a groundwater model to effectively mitigate for impacts to streamflow in Kendall Creek would likely also mitigate for any impacts to water temperature. Nitrate Loading Modeling of nitrate loading to groundwater indicates the potential for nitrate concentrations to increase to levels about the same as the allowable state water quality standards. A groundwater monitoring program should be implemented in high density non-sewered areas (e.g., Paradise Lakes) as well as continued monitoring at the WCWD # drainfield to ensure state water quality standards are not exceeded. If monitoring indicates that groundwater quality standards are likely to be violated as a result of drainfield discharges, these impacts could be effectively mitigated a number of ways: Require additional, high efficiency nitrate removal systems (i.e., recirculating gravel filters) for small, multi-dwelling drainfields rather than a traditional septic system for each dwelling, Expand the sewered area to include all new development in the Columbia Valley/Kendall UGA, and expand sewer treatment plant capacity to treat the additional volume, and/or Reduce the planned density. Additionally, new on-site sewage disposal regulations, which became effective in 007, require increased treatment (i.e., sand filter system) in areas with coarse soils, may reduce the potential for contamination in areas not served by public sewer. If configuration of drainfields in the subarea outside the Columbia Valley/Kendall UGA leads to potential nitrate impacts, then the same set of mitigating measures listed above could apply. 4.. Public Stormwater Facilities No significant impacts to public stormwater facilities were identified for Alternative in Section.. 4. Alternative The potential mitigation measures for Alternative are the same as Alternative. 4. Alternative Modeling of nitrate loading to groundwater indicates the potential for nitrate concentrations to increase to levels about the same as allowable state water quality standards. A groundwater monitoring program should be implemented in high density 60 PROJECT NO JULY 8, 008

68 non-sewered areas (e.g., Paradise Lakes) as well as continued monitoring of the WCWD # drainfield to ensure state water quality standards are not exceeded. If monitoring indicates that groundwater quality standards are likely to be violated as a result of drainfield discharges, these impacts could be effectively mitigated a number of ways: Require additional, high efficiency nitrate removal systems (i.e., recirculating gravel filters) for small, multi-dwelling drainfields rather than a traditional septic system for each dwelling, Expand the sewered area to include all new development in the Columbia Valley/Kendall UGA, and expand sewer treatment plant capacity to treat the additional volume, and/or Reduce the planned density. Additionally, new on-site sewage disposal regulations, which became effective in 007, require increased treatment (i.e., sand filter system) in areas with coarse soils, may reduce the potential for contamination in areas not served by public sewer. If configuration of drainfields in the subarea outside the Columbia Valley/Kendall UGA leads to potential nitrate impacts, then the same set of mitigating measures listed above could apply. Other development under Alternative would be limited to the point that any significant water quantity and quality impacts could be effectively mitigated by implementing the mitigation measures outlined in Section Mitigation Elements Common to All Three Alternatives. Comply with the standards set forth in Ecology s Stormwater Manual 4 and Whatcom County Development Standards. 5. Require 00 percent infiltration and enhanced treatment 6 of stormwater runoff from new development within Critical Aquifer Recharge Areas.. Require phosphorus treatment 7 prior to infiltration within ¼ mile of Sprague, Kendall, or Silver Lakes. 4. Prohibit new facilities that infiltrate stormwater from pollution generating impervious surfaces within the -year time of travel wellhead protection zone. 5. Monitor for potential nitrate impacts to groundwater in high-density non-sewered areas (e.g., Paradise Lakes subdivision) and continued monitoring at the WCWD # drainfield. If monitoring indicates State water quality standards will likely be exceeded, then mitigate through high efficiency nitrate removal systems, connections to sanitary sewer and/or a reduction in density. 6. Implement policies in the draft Foothills Subarea Plan that address water quantity and quality. Selected policies that provide mitigation are set forth below: EN-A Conserve wildlife habitat, salmon habitat, wetlands, river and stream corridors, agricultural land and unique natural features. Work with public and private agencies (Whatcom Land Trust, Audubon Society and Nature Conservancy) to achieve this policy. PROJECT NO JULY 8, 008 6

69 EN-B EN-E EN-G EN-H EN-I EN-J Strongly encourage low impact development standards in the development of all new long and short plats. Work with property owners, citizen groups, the State of Washington, and other agencies in protecting fish and wildlife habitat, (including but not limited to Chinook, bull trout, steelhead, and bald eagle habitat), fishery resources and surface and groundwater quantity and quality of the Foothills Subarea. Promote groundwater of a quantity and quality suitable for domestic consumption by requiring densities consistent with Whatcom County Code 4.05 and low intensity uses in locations with soils of poor quality for on-site sewage systems. Recognize and protect natural wetlands such as swamps, bogs, marshes and ponds as natural catchment basins for stormwater runoff and aquifer recharge. Whatcom County shall assist and encourage the monitoring of water quantity and quality in the Nooksack River system and its tributaries, and in other Subarea drainage systems. Whatcom County shall address any decrease in water quality by additional controls on emissions, discharges or run-off of any pollutants by any user and by controls on development density. Activities that impact water quantity and quality will be consistent with state water law and the critical aquifer recharge area provisions of the Whatcom County Critical Areas Ordinance. 8 An assessment of the effectiveness of the environmental goals and policies of the Draft Foothills Subarea Plan (October, 007) was conducted as a component of this study. The results of the assessment are shown in Table 4.. In general, the goals and policies were found to be effective if fully implemented. Several additions or modifications to the policies are suggested to better mitigate for the potential impacts to surface water and groundwater. We recommend adding a new policy specifically encouraging infiltration, but not within the year time of travel of wellhead protection zones. Other recommendations include expanding LID to include commercial and industrial development (EN-B), adding groundwater monitoring to EN-I, and including preservation of areas closest to the wellheads to EN-F. 6 PROJECT NO JULY 8, 008

70 Table 4. Assessment of Foothills Subarea Plan Goals and Policies related to Surface Water and Groundwater Goal Policy Effectiveness of Implementation Goal EN EN-B RECOMMENDED NEW POLICY EN-C EN-D EN-E Protect surface and ground water quality and quantity and sensitive habitat areas throughout the subarea, consistent with best available science. Strongly encourage low impact development standards in the development of all new long plats and short plats. Protect aquifer recharge and stream baseflows by encouraging infiltration of stormwater where soil characteristics allow, except within the -year time of travel for wellhead protection areas. Identify and manage environmentally sensitive areas to prevent destruction of the resource base and reduce potential losses to property and human life, and to protect and enhance environmental quality. Encourage cooperation among federal and state agencies, municipalities, environmental groups (Whatcom Land Trust, Audubon Society, The Nature Conservancy), and private landowners to enhance the Foothills Subarea's environmental resources. Work with property owners, citizen groups, the State of Washington, and other agencies in protecting fish and wildlife habitat (including but not limited to Chinook, bull trout, steelhead, and bald eagle habitat), fishery resources, and surface and ground water quality and quality of the Foothills Subarea. Goal considered effective if implemented. Low impact development is considered an effective means for mitigating surface water and groundwater quantity and quality impacts. Policy should be expanded to include new commercial and industrial development. Policy implementation considered effective means for mitigating surface water and groundwater quantity impacts. Exclusion of -year time of travel zones protects groundwater quality for water supply uses. Policy implementation considered effective means for mitigating surface water and groundwater quantity and quality impacts. Stakeholder coordination and involvement is essential for addressing water issues. Policy considered effective. Stakeholder coordination and involvement is essential for addressing water issues. Policy considered effective. PROJECT NO JULY 8, 008 6

71 Goal Policy Effectiveness of Implementation EN-F EN-G EN-H EN-I EN-J Goal EN Encourage property owners to obtain conservation easements, conservation grants, and transfer of development rights to enhance the conservation of wildlife habitat, salmon habitat, wetlands, river corridors, agricultural land, historical sites, scenic views, unique natural features and other environmental resources. Promote groundwater of a quantity and quality suitable for domestic consumption by requiring densities consistent with Whatcom County Code 4.05 and low intensity uses in locations with soils of poor quality for on-site sewage systems. Recognize and protect natural wetlands such as swamps, bogs, marshes and ponds as natural catchment basins for stormwater run-off and aquifer recharge. Whatcom County shall assist and encourage the monitoring of water quantity and quality in the Nooksack River system and its tributaries, and in other Subarea drainage systems. Whatcom County shall address any decrease in water quality by additional controls on emissions, discharges or run-off of any pollutants by any user and by controls on development density. Activities that impact water quantity and quality will be consistent with state water law and the critical aquifer recharge area provisions of the Whatcom County Critical Areas Ordinance. County government should work with state and federal agencies to periodically review critical area and public health and safety issues brought about by climate change. Policy implementation considered an effective means for preserving natural resources. Consider including wellhead protection areas within -year time of travel in list of areas to be conserved. Policy considered effective. Nitrate threat to groundwater quality is regulated under WCC 4.05 by controlling lot size or treatment. Policy is generally considered effective. Some wetlands/ponds present in the Foothills subarea are likely groundwater discharge areas. While protection of these would not affect groundwater recharge, it would maintain the natural environment. Monitoring is a cornerstone of water protection measures. Policy should be expanded to include groundwater monitoring for water levels and nitrate. Policy considered effective. Policy should also reference WCC 4.05 for control of drainfield discharges. Goal considered effective if implemented. 64 PROJECT NO JULY 8, 008

72 Limitations Work for this project was performed and this report prepared in accordance with generally accepted professional practices for the nature and conditions of work completed in the same or similar localities, at the time the work was performed. It is intended for the exclusive use of Whatcom County Planning & Development Services for specific application to the referenced property. This report does not represent a legal opinion. No other warranty, expressed or implied, is made. References AESI, 005, Hydrogeologic and Well Head Protection Evaluation, Balfour Village Development, prepared for Aiki Homes, Inc, November. Ecology, 00a, Stormwater Management Manual for Western Washington, publication numbers through , February. Ecology, 00b, Permit Writers Manual, Chapter 8, Water Quality-Based Limits for Groundwater. King County, 005, King County, Washington, Surface Water Design Manual, King County Department of Natural Resources, January 4. Prince George s County, 999, Low Impact Development: An Integrated Design Approach, Prince George s County, Maryland, Department of Environmental Resource Programs and Planning Division, January. Puget Sound Action Team, 005, Low Impact Development Technical Guidance Manual for Puget Sound, rev. May 005. Rongey, R.J., 974, Comments concerning Peaceful Valley impact statement: Prepared for Ronald T. Jepson & Associates, February 8. Rongey, R.J., 975a, Ground water: Columbia Valley: Prepared for Whatcom County Water District no., July. Rongey, R.J., 975b, Ground water: Columbia Valley: Prepared for Whatcom County Water District no., July. Utah State University, 00a, Groundwater Quantity Report for WRIA, Phase II, November 0. Utah State University, 00b, WRIA Surface Water Quality Data Collection and Assessment, Phase II Summary Report Final Draft, December 7. PROJECT NO JULY 8,

73 Utah State University, 00a, Final Draft Report for Surface Water Quantity Task, Assessment of Stream Flow and Climatological Data Available for Use in WRIA Watershed Management, Technical Studies for the WRIA Watershed Management Project, January 0. Utah State University, 00b, Final Draft Report for Surface Water Quantity Task, Estimation of Long-Term Mean Monthly Water Balance Calculations, Technical Studies for the WRIA Watershed Management Project, January 0. Utah State University, 00c, Final Draft Report for Surface Water Quantity Task, Estimation of Surface Water Components of the WRIA Water Balance, Technical Studies for the WRIA Watershed Management Project, January 0. Whatcom County, 00, Whatcom County Development Standards, Chapter Stormwater Management, revised September. 66 PROJECT NO JULY 8, 008

74 Endnotes Draft Foothills Subarea Plan (October 007) Exhibit B of Contract for Services from Agreement for Aspect Consulting LLC, April 9, 008 Exhibit B of Contract for Services from Agreement for Aspect Consulting LLC, April 9, Exhibit B of Contract for Services from Agreement for Aspect Consulting LLC, April 9, Exhibit B of Contract for Services from Agreement for Aspect Consulting LLC, April 9, Number of dwellings from from Matt Aamot, Whatcom County, July 0, AESI 005, Rongey 974, 975a, 975b 8 Source of streamflow for USGS gages from Utah State University 00a, p.. Source of streamflow for Ecology stations was determined by reviewing the timing of average monthly runoff values for the period of record 9 Utah State University 00c, p Rongey 975b, p.. Draft Foothills Subarea Plan (October, 007), p. 6. Utah State University 00c, p. 8. Utah State University 00b, 5. 4 Utah State University 00c, p. 7 and p Utah State University 00a, p Utah State University 00c, p. 6 7 Personal communication from Ted Thaygesen, WDFW to Erick Miller, Aspect Consulting, June, Puget Sound Action Team 005, p Draft Foothills Subarea Plan (October 007), p Although it is recognized that the lots in Campers Paradise aren t always occupied, these lots were assumed to generate runoff in the same manner as a typical dwelling. This approach is considered conservative for modeling runoff (i.e. slightly overestimate stormwater runoff). However, since the number of recreational lots in Campers Paradise does not change between any of the alternatives, this approach has no bearing on the analysis of impacts. Existing lots: Campers Paradise 5 (Matt Aamot, Whatcom County, personal communication, July 4, 008), Dwelling Units: Peaceful Valley 5, Paradise Lakes 985 ( from Matt Aamot, Whatcom County, July 4, 008). From from Matt Aamot, Whatcom County, July 0, 008. Based on reducing the typical area of roads of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.75 reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and.8 DU/acre (%, Ecology, 005, Vol. p. -5) The.8 Du/acre is assumed based on maximum build out density of the subdivisions (see Section..) since the roads are already existing for that density. 4 Based on reducing the typical area of roofs of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.64 reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and.4 DU/acre (8%, Ecology, 005, Vol. p. -5). 5 Based on reducing the typical area of driveways of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.64 reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and.4 DU/acre (8%, Ecology, 005,Vol., p. -5). 6 Current impervious area estimated by Whatcom County ( s from Matt Aamot, Whatcom County, July 0 and 4, 008). 7 Puget Sound Action Team, 005, p.. PROJECT NO JULY 8,

75 8 King County, 005, p Puget Sound Action Team, 005, p.. 0 Utah State University, 00a. Information from well logs obtained from Washington State Department of Ecology Well Log Database. Utah State University, 00a. Utah State University, 00a, p AESI 005, p.9. 5 AESI 005, p.. 6 AESI 005, p AESI Information from Washington Department of Health Office of Drinking Water Sentry Database. All public water systems use groundwater sources from wells except Deming Water Association and Glacier Springs Water System which use spring sources. 9 Calculated connections represent Equivalent Residential Units (ERU) and do not necessarily represent numbers of dwellings. 40 WDOH approved connections are based on criteria including water system capacity and water rights 4 Draft Foothills Subarea Plan (October 007), p.. 4 A total of 5 recreational lots are known at Camper s Paradise leaving a balance of 8 PWS connections that are unknown. 4 Information from Ecology s Well Log Database indicates there are fewer than 0 exempt wells in the Columbia Valley UGA. 44 Based on a weighted average of WCWD # ADD of 60 gpd (from WCWD # Water System Plan February 005, p. 4) for 47 connections (DOH database), and EWSD#9 ADD of 00 gpd ( from Richard Banel Water District #9 commissioner to Matt Aamot, Whatcom County, July 5, 008) and 04 residential connections (total of,67 connections [DOH database] minus nonresidential connections. 45 Return flow refers to the amount of water not consumed by a household that is infiltrated back to groundwater through on-site septic systems and community drainfields. 46 A return flow value of gpd (Ecology default value for nitrate loading model, see Section..) was used for all EWSD#9 residential connections. A return flow of 49 gpd was used for all WCWD # connections assuming 0% of total water use was lost to leakage (WCWD # Water System Plan, February 004, p. 4) in addition to the standard gpd of return flow per dwelling. The total return flow value represents a weighted average for the two water systems. 47 From from Richard Banel Water Distric #9 commissioner to Matt Aamot, Whatcom County, July 5, Draft Foothills Subarea Plan (October 007), p. 49 This number is similar to the approximate number of,500 recreational lots reported in the Draft Foothills Subarea Plan (October 007)p.. However the,500 lots was an approximate value for three recreational developments, one of which (Camper s Paradise) is in the Columbia Valley/Kendall UGA. The,48 value was calculated based on PWS records of connections with water systems that are known or assumed to be primarily recreational developments. 50 Glacier: capita per dwelling. Maple Falls:.48 capita per dwelling. Deming:.6 capita per dwelling. Remaining subarea.7 capita per dwelling. Draft Foothills Subarea Plan (October 007) p Utah State University 00b, Sections..4 and Utah State University 00b, Sections.. and... 5 Utah State University 00b, Sections.. and Utah State University 00b, Sections.. and Draft Foothills Subarea Plan (October 007), p CFR Draft Foothills Subarea Plan (October 007), p Information from Washington Department of Health Office of Drinking Water Sentry Database 68 PROJECT NO JULY 8, 008

76 59 Ecology CSCS Listing, Information from Washington Department of Health Office of Drinking Water Sentry Database 6 AESI 005, p Draft Foothills Subarea Plan (October 007), p Information from Washington Department of Health Office of Drinking Water Sentry Database reports WCWD # currently serves 47 connections for water service, although other sources indicate this number may be Information from Washington Department of Health Office of Drinking Water Sentry Database 65 Draft Foothills Subarea Plan (October 007), p Draft Foothills Subarea Plan (October 007), p Ecology CSCS Listing, Information from Washington Department of Health Office of Drinking Water Sentry Database 69 Information from Washington Department of Health Office of Drinking Water Sentry Database 70 Whatcom County inventory of culverts was performed in December 005. Ditches along Limestone road were inventoried on February 7, 006. Ditch along Eason Road was inventoried on April 9, Note that the flows in the Middle Fork may be influenced by changes in the City of Bellingham s water supply diversion. However, analyzing those changes is outside the scope of this analysis. 7 Ecology, Whatcom County, Ecology, Whatcom County, From from Matt Aamot, Whatcom County, July 0, Note that these lots include the 5 lots in Campers Paradise, as explained in Section.. Stormwater. 78 Based on reducing the typical area of roads of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.75 reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and.8 DU/acre (%, Ecology, 005, Vol. p. -5). 79 Based on reducing the typical area of roofs of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.75 reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and.8 DU/acre (%, Ecology, 005, Vol. p. -5). 80 Based on reducing the typical area of driveways of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.75 reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and.8 DU/acre (%, Ecology, 005,Vol., p. -5). 8 King County, 005, p Based on reducing the typical area of roads of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.49 reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and.7 DU/acre (%, Ecology, 005, Vol. p. -5). 8 Based on reducing the typical area of roofs of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.49 reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and.7 DU/acre (%, Ecology, 005, Vol. p. -5). 84 Based on reducing the typical area of driveways of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.49 reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and.7 DU/acre (%, Ecology, 005,Vol., p. -5). 85 Based on reducing the typical area of stormwater ponds of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of The 0.49 reduction factor PROJECT NO JULY 8,

77 is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. - 0) and.7 DU/acre (%, Ecology, 005,Vol., p. -5). 86 King County, 005, p Based on maximum impervious area allowed under WCC Area estimated by Whatcom County ( from Matt Aamot, Whatcom County, July 4, 008) 89 Puget Sound Action Team, 005, p.. 90 Based on reducing the typical area of roads of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of 0.. The 0. reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and 0.8 DU/acre (%, Ecology, 005, Vol. p. -5). 9 Based on reducing the typical area of roofs of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of 0.. The 0. reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and 0.8 DU/acre (%, Ecology, 005, Vol. p. -5). 9 Based on reducing the typical area of driveways of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of 0.. The 0. reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. -0) and 0.8 DU/acre (%, Ecology, 005,Vol., p. -5). 9 Based on reducing the typical area of stormwater ponds of residential development at 4 DU/acre (Prince George s County, 999, p. -0) by multiplying by a factor of 0.. The 0. reduction factor is based on relative total impervious percent of 4 DU/acre (4% Prince George s County, 999, p. - 0) and 0.8 DU/acre (%, Ecology, 005,Vol., p. -5). 94 King County, 005, p Based on maximum impervious area allowed under WCC chapter Area estimated by Whatcom County ( from Matt Aamot, Whatcom County, July 4, 008) 97 Puget Sound Action Team, 005, p.. 98 Puget Sound Action Team, 005, p.. 99 Maximum impervious area for the Kendall STC calculated by Whatcom County ( from Matt Aamot, Whatcom County, July 4, 008). 00 Prince George s County, 999, p Prince George s County, 999, p Prince George s County, 999, p King County, 005, p Prince George s County, 999, p Prince George s County, 999, p King County, 005, p Note that the values in Table. represent an unmitigated scenario, that is none of the runoff generated is infiltrating in a formal stormwater facility. 08 Information from Whatcom County Water District # Water System Plan, February 005 p. 4 and Draft Foothills Subarea Plan (October 007) p This value is the same as the existing ADD since it reflects improvements to infrastructure to limit leaks that EWSD#9 has already implemented ( s from Richard Banel Water District #9 to Matt Aamot, Whatcom County, July 4, 008 and July 5, 008). 0 For example under Alternative, consumptive use increases 0 acre-feet per year (see Table.6) and groundwater recharge is reduced by 597 acre feet per year (see Table.4). The sum of these two impacts is = 779 acre feet per year. AESI 005, p.. Utah State University 00b, Sections..4 and..4 AESI 005, p.. 4 Ecology, Whatcom County, Puget Sound Action Team, Ecology, PROJECT NO JULY 8, 008

78 8 Ecology, Whatcom County, Ecology, 005. Ecology, 005. Draft Foothills Subarea Plan (October 007), p. 96. Draft Foothills Subarea Plan (October 007), p Ecology, Whatcom County, Ecology, 005, p Ecology 005, p Puget Sound Action Team, 005, p. 6. PROJECT NO JULY 8, 008 7

79 Vedder Mountain Kendall Creek Watershed Maple Creek # ree k Black Mountain Doaks Creek lde # rc Red Mountain ) " 54 U V yo n Can k ree k Cr ee ep Corn e De orne ll Cr eek Wes tc Litt le C t Cre n Ke y ne a Canyon L ke ee Cr k k ee Cr k Canyon Lake ive r Middle Fork Nooksack Subbasin Rocky Creek Deming Cr ee ter rw a ck R i ver Sister Creek Gal brai th C reek Bowman Mountain# Wa rm Fork Nook sa Cre ek Cl ea Midd le 9 V U Acme Foothills Subarea Boundary Columbia Valley/Kendall UGA Small Towns Watercourses 0 0,000 0,000 0,000 40,000 Feet Highways # Mountain Peak DATE: Subbasins and Watersheds Foothills Subarea SEIS Whatcom County, Washington June 008 DESIGNED BY: PPW PROJECT NO DRAWN BY: PPW REVISED BY: PPW FIGURE NO.. T:\projects_8\WhatcomCounty\ Foothills-SEIS\Delivered\Subbasins_Watersheds.mxd ) " k Falls C re ek eek Seymour Cr South Fork Nooksac k River Heisl e rs C re ek Po rte r Cr ee k kr k ee Cr ell ) " sa c ee Cr No ok ree k ier C ll Be 54 U V h itc M k ree ek Slide Mountain yc Glacier Glac # ) " n Cre Wil d ca k pso Thom H ee Cr Davis Creek or Raceh eek se Cr k ric ed Gallop Creek kn North Fork Nooksack Subbasin ek For North er ck Riv o o k sa ek k ll Cr e Co al Cr ee re Kendall C Sumas Mountain la cau Ma ek Cre ek Kendall ree k Maple Falls ut C ) " Loo ko eek Cr Kendall Lake Coal Creek 547 V U Sprague Lake # Frost C ree k Silver Lake Bo u g id nr Columbia Valley/ Kendall UGA k s llin Co e Br e ck e re ec # UNITED STATES 9 V U I CANADA

80 I &< EWSD #9 S0 / WELL # Water Service Provided by Evergreen Water and Sewer District (EWSD) #9 Camper's Paradise Subdivision WCWD # Well PW- WCWD # Well PW- &< &< &< WCWD # Drainfield Paradise Lakes Subdivision EWSD #9 S0 / WELL # Peaceful Valley Subdivision Water and Sewer Service Provided by Whatcom County Water District (WCWD) # Kendall Lake EWSD #9 S0 / WELL # WCWD # Sewer Treatment Plant Sprague Lake &< Paradise Lakes Subdivision Water Service Provided by Evergreen Water and Sewer District #9 Columbia Valley/Kendall UGA Alternative - Extent of Planning Area Boundary Alternative - Extent of Current Planning Area Boundary #06000 #* Kendall Small Town # # # # # Alternative - Extent of Planning Area Boundary # # # # # # # # # # # # # # # Evaluation Area (59 Acres) Water District Service Areas #* Former USGS Gaging Stations Highways Small Town Tax Parcels Watercourses #06500 #* North Fork Nooksack River 0,500,000 4,500 6,000 Feet Columbia Valley/ Kendall UGA Overview Foothills Subarea SEIS - Whatcom County, Washington DATE: DESIGNED BY: DRAWN BY: REVIS ED B Y: June 008 PPW PPW PPW PROJECT NO FIGURE NO.. T:\projects_8\WhatcomCounty\ Foothills-SEIS\Delivered\UGAs.mxd

81 Seymour Creek CANADA UNITED STATES I Silver Lake Columbia Valley/ Kendall UGA Maple Creek Frost Creek Collins Creek Breckenridge Creek Doaks Creek Boulder Creek Coal Creek Sprague Lake Kendall Lake Kendall Creek ") Kendall North Fork Nooksack River ") Maple Falls Canyon Creek Coal Creek Lookout Creek Racehorse Creek Wildcat Creek Hedrick Creek ") Glacier Davis Creek Thompson Creek Macaulay Creek Bell Creek Kenney Creek West Cornell Creek Cornell Creek Gallop Creek Little Creek Deep Creek Glacier Creek Mitchell Creek ") Deming Nooksack River Canyon Lake Creek Canyon Lake Rocky Creek Porter Creek Heislers Creek Falls Creek Clearwater Creek South Fork Nooksack River Middle Fork Nooksack River Warm Creek Galbraith Creek Sister Creek ") Acme Foothills Subarea Boundary Columbia Valley/Kendall UGA Alluvial Aquifers Watercourses Surficial Geology (WA DNR :00K) Bedrock Quaternary Alluvial Deposits Quaternary Glacial Deposits Ice 0 0,000 0,000 0,000 40,000 Feet Geology and Surficial Aquifers Foothills Subarea SEIS Whatcom County, Washington DATE: DESIGNED BY: DRAWN BY: REVIS ED B Y: June 008 PPW PPW PPW PROJECT NO FIGURE NO.. T:\projects_8\WhatcomCounty\ Foothills-SEIS\Delivered\geology.mxd

82 M 7 4 ) " 6 ck 7 Ri 7 4 r ve sa ok No ck River re ek 9 8 ) " Acme le Fo rk N o ok s a ck R iv er reek Mid d Frost C 6 9 V U eek Seym ou r Cr 5 lers C reek Heis South Fork Nooksa Number of Well Logs by Qtr-Qtr Section " " -5 " 6-0 " + Foothills Subarea Boundary Columbia Valley/Kendall UGA Small Towns Watercourses Highways 0 0,000 0,000 0,000 40,000 Feet DATE: Well Logs by Quarter-Quarter Section Foothills Subarea SEIS - Whatcom County, Washington June 008 DESIGNED BY: PPW PROJECT NO DRAWN BY: PPW REVISED BY: PPW FIGURE NO..4 T:\projects_8\WhatcomCounty\ Foothills-SEIS\Delivered\welllogs.mxd Falls C ree k a Canyon Lake 4 ek ke Cre L on ny Ca 8 er ll C ree k u ld o rne ek C re 6 Deming Glacier Sister Creek l ) " Wa rm 4 he at itc 5 k rw b ra ith C ek re lc Gal 5 k e re ree k ie r C C reek ree yc 4 ho rse He dr C ick ne 5 ca n Ke Ma 4 k 4 ee Cr 4 ll y ul a Rac e 4 ek C re Bo Be C reek Glac Wes tc 4 k Davis Creek 6 ek Maple Falls 4 C re y on Ca n Rocky Creek No er ck Riv o o ks a th For k N r at C Cree k pso n Th o m 6 7 ) " ek 5 C re ou t 4 ) " Lo o k Co al Creek k 5 6 Cr ee 7 ep De 4 ree k ec Lit tl 7 Gallop Creek k k rc re e Ken d al l Creek 5 ll Cr e ek Co al Cr ee Kendall Lake re ek k Kendall 6 5 Sprague Lake Co rn e Cr ee ee Cr 547 V U 4 6 Doaks Creek 6 4 Cr eek 4 ins Columbia Valley/ Kendall UGA Wild c 5 Ma p le er 9 5 Cl ea 4 Silver Lake Po r te ke 4 id nr Br ec k ll Co ee Cr 4 ge UNITED STATES 9 V U I CANADA