CHAPTER 2 Water Demands

Transcription

1 CHAPTER 2 Water Demands This chapter provides an overview of the City s water service area and describes the City s historical annual water use. Subsequent sections of this chapter examine projected water conservation and describe the data and methodology used to develop future water demand projections. The key sections of the chapter are: Service Area Description Historical Annual Water Use Water Conservation Water Demand Projections A key objective of this water demand evaluation is to confirm the anticipated water demand requirement and its associated timing, particularly due to the recent significant demand reductions caused by a combination of droughts and poor economic conditions. Future water demands developed in this chapter will subsequently be allocated in the hydraulic model to evaluate system performance under projected 2035 demand conditions. The future water system evaluation will help update recommendations presented previously in the 2006 Water Master Plan Update and prioritize future water system facilities. 2.1 SERVICE AREA DESCRIPTION The City is located in Northern California approximately 50 miles north of San Francisco and 30 miles east of the Pacific Ocean, and is the county seat for Sonoma County. The City s water service area is roughly coterminous with the City limits, but does extend slightly beyond the City limits in some areas, as shown on Figure 2-1. Land use within the City is primarily residential, but also includes some agricultural, industrial, commercial, and recreational land uses. The City obtains its water supply from two sources. The primary supply source is treated water purchased from the Sonoma County Water Agency (SCWA). The City also has five potable groundwater wells, two of which can be used to supplement water supply purchased from SCWA, and the remaining three wells are for emergency use only (only two of these emergency wells are currently operational). 2.2 HISTORICAL ANNUAL WATER USE This section summarizes the City s historical water purchases from the SCWA and local groundwater production, water consumption, unaccounted for water, and water system peaking factors Water Purchases and Groundwater Production Prior to 1959, the City relied almost exclusively on groundwater to supply its customers. Then, beginning in June 1959, through 2006, with the availability of water from SCWA, the City began to rely exclusively on water purchased from SCWA. The City also maintains a local source of groundwater supply, which prior to 2007 (but after 1959), had only been used for emergency purposes. Since the introduction of potable groundwater supply in 2007 to supplement water purchased from SCWA, the City has received on average approximately 95 percent of its water August 2014 o\c\405\ \wp\mp\071613_2ch2 2-1 City of Santa Rosa

2 Chapter 2 Water Demands supply from SCWA. Table 2-1 summarizes the City s historical annual water purchases from SCWA and groundwater production from 2006 to Table 2-1. Historical Annual Water Purchases and Groundwater Production, MG (AF) Year Purchased from SCWA Groundwater Total 2006 (a) 7,756 (23,803) 0 (0) 7,756 (23,803) 2007 (a) 7,397 (22,700) 271 (832) 7,668 (23,532) 2008 (a) 7,137 (21,903) 489 (1,501) 7,626 (23,405) 2009 (b) 6,157 (18,895) 440 (1,350) 6,597 (20,245) 2010 (b) 6,033 (18,514) 298 (914) 6,331 (19,428) 2011 (b) 5,598 (17,180) 410 (1,259) 6,008 (18,439) 2012 (b) 6,306 (19,354) 258 (791) 6,564 (20,145) 2013 (c) 6,743 (20,692) 369 (1,131) 7,111 (21,823) (a) Source: CSR_Use and Production Statistics_ (b) Source: CSR_ProdandUse_ xlsx, received from City staff on 8/29/13. (c) Source: 2013_Production and Use Statistics.pdf, received from City staff on 5/20/14. MG = Million gallons; AF = Acre-feet. Water use in the City significantly decreased in 2009 through 2011 and then increased in 2012 and 2013 with 2013 water use back above the 2009 level. It should be noted that this more recent, lower, water use is not representative of normal water use characteristics for the City as it has been significantly affected by the following factors: Drought Conditions; Water Shortage Conditions; and Economic Conditions. Dry year conditions in 2007 and 2008 caused SCWA to request voluntary 15 percent reductions in water use from all of its water contractors. In 2009, further drought conditions caused the SCWA to implement the Water Shortage Allocation Methodology and provide monthly allocations to each of its water contractors. In response, the City adopted Stage 1 of the Urban Water Shortage Contingency Plan requesting customers to reduce their water use. The recent economic recession and high amounts of vacancy in existing residential and commercial customer accounts from 2007 to 2010 also had a significant effect on water usage Water Consumption The City tracks its water consumption through customer meter records. Table 2-2 summarizes the City s historical annual water consumption by customer type. The predominant water use in the City is by residential customers, which accounts on average for approximately 73 percent of the total annual water consumption. August 2014 o\c\405\ \wp\mp\071613_2ch2 2-2 City of Santa Rosa

3 Chapter 2 Water Demands Table 2-2. Historical Annual Water Consumption by Customer Type, MG Year Customer Type 2006 (a,b) 2007 (a) 2008 (a) 2009 (c) 2010 (c) 2011 (c) 2012 (c) 2013 (d) Residential Single Family 4,107 3,996 4,020 3,424 3,215 3,202 3,458 3,565 Multi-Family 1,085 1,076 1,106 1,053 1,045 1,040 1,078 1,105 Subtotal Residential 5,192 5,072 5,126 4,477 4,260 4,242 4,536 4,670 Non-Residential Commercial 1, Industrial Institutional Irrigation Other (e) Subtotal Non-Residential 1,986 2,003 1,936 1,704 1,454 1,481 1,664 1,746 Total 7,178 7,075 7,062 6,181 5,714 5,723 6,200 6,416 Percent Residential 72% 72% 73% 72% 75% 74% 73% 73% Percent Non-Residential 28% 28% 27% 28% 25% 26% 27% 27% (a) (b) (c) (d) (e) Source: CSR_Use and Production Statistics_ Water consumption from Industrial, Institutional, and Other customer types included in Commercial customer type. Source: CSR_ProdandUse_ xlsx, received from City staff on 8/29/13. Source: 2013_Production and Use Statistics.pdf, received from City staff on 5/20/14 Includes revenue (i.e., construction meters) and non-revenue water consumption Unaccounted for Water Unaccounted for water (UAFW) is the difference between the quantity of water purchased/produced and the quantity of water consumed or billed. UAFW typically includes all water not measured/metered within a system that is used for incidental purposes such as hydrant testing, fire-fighting, and water main flushing. UAFW also includes other unintended uses such as system leaks, unauthorized connections/water theft, water main breaks, and meter inaccuracies. The City s annual water production, water consumption, and UAFW are summarized in Table 2-3. In the last eight years, the UAFW has ranged from 4.7 percent to 9.8 percent, with an average of 7.3 percent. West Yost recommends the use of this average UAFW factor of 7.3 percent for planning purposes in this because this average accounts for some of the variability between the historical annual UAFW. This recommended UAFW factor of 7.3 percent is slightly higher than the UAFW factor (7.0 percent) used in the City s 2006 as it incorporates the more recent data (2006 to 2013), which documents that the UAFW was as high as 9.8 percent. However, this recommended UAFW factor is slightly lower than the UAFW factor (7.9 percent) used in the City s 2010 Urban Water Management Plan (UWMP) based on the data available during that period. Future August 2014 o\c\405\ \wp\mp\071613_2ch2 2-3 City of Santa Rosa

4 Chapter 2 Water Demands specific City UAFW data should be used to re-calculate and update this UAFW value for the City s water system to better reflect actual conditions. Table 2-3. Unaccounted For Water Year Total Water Production, MG (a) Total Water Consumption, MG (b) UAFW, MG Percent of Total Water Production ,756 7, % ,668 7, % ,626 7, % ,597 6, % ,331 5, % ,008 5, % ,564 6, % ,111 6, % Average 7.3% (a) (b) Refer to Table 2-1. Refer to Table Water System Peaking Factors Water system facilities are generally sized to meet peak demand periods. The peaking conditions of most concern for facility sizing are typically maximum month demand, maximum day demand with fire flow and peak hour demand. Peak water use is typically expressed as a ratio, or peaking factor, dividing the peak water use by the average daily water use. These peaking factors are then used to calculate maximum month, maximum day and peak hour water use conditions Maximum Month Water Use Figure 2-2 presents the City s historical monthly total water purchases and groundwater production between 2006 and Table 2-4 summarizes the total water purchased and groundwater produced during the maximum month between 2006 and 2013 and includes the calculated maximum month peaking factors. In the last eight years, the maximum month peaking factor has ranged from 1.4 to 1.7, with an average of 1.5. West Yost recommends a maximum month peaking factor of 1.5 for planning purposes, consistent with the City s 2006 Water Master Plan Update. August 2014 o\c\405\ \wp\mp\071613_2ch2 2-4 City of Santa Rosa

5 Chapter 2 Water Demands Table 2-4. Summary of Maximum Month Peaking Factors Year Maximum Month Average Day Water Production, mgd (a) Maximum Month Water Production, mgd Average Day to Maximum Month Peaking Factor 2006 (b) July (b) July (b) June (c) August (c) August (c) August (c) July (d) July Average 1.5 (a) Refer to data presented in Table 2-1. (b) Source: CSR_Use and Production Statistics_ (c) Source: CSR_ProdandUse_ xlsx, received from City staff on 8/29/13. (d) Source: 2013_Production and Use Statistics.pdf, received from City staff on 5/20/14. mgd = million gallons per day Maximum Day and Peak Hour Water Use Both the City and the SCWA do not currently have direct data available on actual maximum day or peak hour demands. Therefore, consistent with the recommendations in the 2006 Water Master Plan Update, peaking factors of 2.0 and 3.5 will be used to estimate maximum day and peak hour demands, respectively. These factors are commonly used in the water industry to convert average day demands into maximum day and peak hour demands Summary of Peaking Factors Used in Master Plan Analysis Table 2-5 summarizes the maximum month, maximum day, and peak hour peaking factors that will be used for evaluations in this. Table 2-5. Adopted Peaking Factors Demand Condition Average Day During Maximum Month Maximum Day Peak Hour Peaking Factor 1.5 times average day demand 2.0 times average day demand 3.5 times average day demand August 2014 o\c\405\ \wp\mp\071613_2ch2 2-5 City of Santa Rosa

6 Chapter 2 Water Demands 2.3 WATER CONSERVATION This section summarizes the City s water conservation targets required to comply with Senate Bill x7-7, (i.e., 20x2020 Legislation or SB 7), which requires urban water purveyors to reduce their per capita water use by 20 percent by As documented in the City s 2010 UWMP, the City s per-capita water use targets are 136 gallon per capita per day (gpcd) in 2015 and 127 gpcd in Compliance with 20 x 2020 Legislation In February 2008, Governor Arnold Schwarzenegger called for a statewide 20 percent reduction in per capita water use by 2020, and asked state and local agencies to develop a more aggressive plan of water conservation to achieve the goal. A team of state and federal agencies (the 20x2020 Agency Team) consisting of the California Department of Water Resources (DWR), State Water Resources Control Board (SWRCB), California Energy Commission, Public Utilities Commission, Department of Public Health, Air Resources Board, CALFED Program, U.S. Bureau of Reclamation (USBR), and the California Urban Water Conservation Council was formed to develop a statewide implementation plan for achieving this goal. On November 10, 2009, Governor Arnold Schwarzenegger signed SB 7, one of several bills passed as part of a comprehensive set of new Delta and water policy legislation. SB 7 requires a 20 percent reduction in statewide urban per capita water usage by 2020 and establishes various methodologies for urban water suppliers to establish their interim (2015) and final (2020) per capita water use targets. Four methodologies are identified in SB 7 for establishing per capita water use targets: Method 1: A 20 percent reduction from historical baseline per capita water use based on a 10-year running average per capita water use ending between December 31, 2004 and December 31, Method 2: Per capita water use based on 55 gallons per capita per day water use for indoor residential water use, landscape irrigation use based on water efficiency equivalent to the standards of the Model Water Efficient Landscape Ordinance, and a 10 percent reduction from baseline commercial, industrial and institutional (CII) water use. Method 3: 95 percent of the hydrologic region targets established for per capita water use based on the April 2009 Draft 20x2020 Water Conservation Plan. Method 4: A provisional approach that considers the water conservation potential from (1) indoor residential savings, (2) metering savings, (3) commercial, industrial and institutional savings, and (4) landscape and water loss savings. An agency can choose to use any of the four methods. Based on the 2010 UWMP, the City has adopted Method 3 and incorporated the minimum reduction requirement with a calculated 2020 water use target of 127 gpcd. August 2014 o\c\405\ \wp\mp\071613_2ch2 2-6 City of Santa Rosa

7 Chapter 2 Water Demands 2.4 WATER DEMAND PROJECTIONS This section presents the demand projection methodologies used to estimate future potable water demands within the City s water service area, and presents the demand projections through the 2035 buildout time frame. A discussion regarding projected recycled water use is also provided below Projected Recycled Water Use The City owns and operates the Subregional Water Reuse System, which produces recycled water for irrigation and other approved non-potable uses to serve the Cities of Santa Rosa, Cotati, Rohnert Park, and Sebastopol including South Park County Sanitation District and portions of unincorporated Sonoma County. The City has historically used approximately 153 acre-feet or 50 MG per year of recycled water for urban landscape irrigation. The City s current and historic recycled water use has been limited to areas within close proximity to the Subregional Water Reuse System s distribution network. In December 2007, the City approved the Santa Rosa Urban Reuse Project, which could potentially serve up to 3,000 af/yr of recycled water to offset existing potable water use. The Santa Rosa Urban Reuse Project will be implemented in phases to allow the City flexibility to develop this water supply source incrementally as more supply is needed. The City selected Phase 1 West as the first phase of the Santa Rosa Urban Reuse Project to be implemented. As documented in the 2010 UWMP, the City projects Phase 1 West to provide an additional 750 af/yr or 244 MG of recycled water supply by Therefore, by 2025 it is projected that the City will utilize approximately a total of 1,100 af/yr or 358 MG of recycled water to offset potable water use. It is anticipated that the City will only need to build Phase 1 West to meet recycled water demands through Currently, only the first portion of Phase 1 West (Pilot Project at West College) has been completed with grant funds. This project is estimated to offset approximately 60 af/yr or 20 MG of existing potable water use. 1 Discussions with City staff indicate that the timing for the remaining projects in the Phase 1 West plan has not yet been determined and that additional projects would most likely be completed with grant funding. Because the timing of the remaining projects in the Phase 1 West plan is not currently known, the potable water offset from the proposed additional recycled water use was not included to provide a more conservative estimate of required potable water supply to meet projected water demands Land Use Based Projections Future water demand projections were developed using land use based unit water demand factors and an estimate of vacant land based on data from the City s general and specific land use plans. The methodology used to develop unit water demand factors and the resultant water demand projection is discussed in the following sections. 1 Source: Implementation Options TM, Winzler & Kelly, November 12, August 2014 o\c\405\ \wp\mp\071613_2ch2 2-7 City of Santa Rosa

8 Chapter 2 Water Demands Unit Water Demand Factors To develop updated unit water demand factors, City staff provided West Yost with spatiallylocated water meter records from 2006 to 2012 and parcel data (with General Plan land use designations assigned) in Geographical Information System (GIS) format. The spatially-located water meter records from 2006 to 2012 were linked to the parcel data using the Assessor s Parcel Number (APN). This linkage provided the means to then calculate the water use by area for each land use designation using the water demand data from the water meter records and the acreage from the parcels that the water meter records were linked to. Figure 2-3 illustrates the methodology used to link the water meter records to the parcel data. Figure 2-3. Illustration of Methodology for Linking Water Meter Records to Parcel File Table 2-6 summarizes the percentage of total annual metered water demand that was spatially linked to the parcel data for the City. Some of water meter records did not have an APN assigned and could not be linked to the parcel data. As shown in Table 2-6, over 99 percent of the annual metered water demand was linked to the parcel file. The remaining metered water demand, which was not linked to the parcel file, may be located in new developments whose APNs were not yet available in the City s parcel data. The following sections provide a discussion of the development of residential and non-residential unit water demand factors using the linked data described above. August 2014 o\c\405\ \wp\mp\071613_2ch2 2-8 City of Santa Rosa

9 (a) Year Table 2-6. Summary of Potable Metered Water Demand Spatially Linked to Parcel File (a) Actual Metered Demand, kgal Actual Metered Demand with APN, kgal Actual Metered Demand with APN Linked to Parcel File, kgal Percent of Actual Metered Demand with APN Linked to Parcel ,596,357 6,371,011 6,322, % ,949,604 6,718,054 6,669, % ,060,442 6,822,608 6,775, % ,040,047 5,845,515 5,798, % ,700,995 5,533,228 5,496, % ,714,225 5,523,367 5,489, % ,192,995 5,953,271 5,916, % Data developed from WaterMeters_geocode_consumpt.shp and SR_parcels.shp provided by City staff. o\c\405\ \e\t3\unitfactors Last Revised: City of Santa Rosa

10 Chapter 2 Water Demands Residential Unit Water Demand Factors Calculation of the residential unit water demand factors required the use of the average dwelling unit density (unit/acre or unit/ac) to convert the calculated unit water demand factors from gallons/acre/day to gallons/unit/day. Table 2-7 summarizes the average dwelling unit density used to calculate the residential unit water demand factors. Table 2-7. Summary of Average Dwelling Unit Density Land Use Designation Dwelling Unit Density (a), units/ac Average Dwelling Unit Density (b), units/ac Very Low Density Residential 0.2 to Low Density Residential 2 to 8 5 Medium Low Density Residential 8 to Medium Density Residential 8 to Medium High Density Residential 18 to (a) (b) Data obtained from General Plan Land Use Diagram from the City s website. Data obtained from Table 3-7 in the June The water use records linked to the City s parcel data were then used along with the average dwelling unit density as shown in Table 2-7 to calculate residential unit water demand factors (gallons/unit/day) by taking the total annual water demand by land use designation; dividing that by the associated total parcel acreage having water demand linked to it; and then dividing that calculated total by the average dwelling unit density. Table 2-8 summarizes the new residential unit water demand factors calculated for 2006 to Residential unit water demand factors developed previously for 2002 to 2005 were also included for comparison. Figures 1 through 5 in Appendix A present the historical residential unit water demand factors graphically. Typically, a unit water demand factor for each land use designation is recommended based on an average of all available data. However, a review of the City s historical residential unit water demand factors (see Appendix A) indicate that the water use per dwelling unit for all of the residential land use designations were generally lower from 2009 to As discussed above, the water use in the more recent years is atypical, affected by drought, water shortage and poor economic conditions and is not representative of normal water use characteristics for the City. Therefore, the unit water demand factors were also evaluated using a second method for comparison with the historical (2002 to 2012) average. This second method calculated average unit water demand factors by eliminating any annual unit water demand factor that is outside one standard deviation from the historical average for each land use designation. Table 2-9 presents the historical (2002 to 2012) average residential unit water demand factors along with the average residential unit water demand factors within one standard deviation. August 2014 o\c\405\ \wp\mp\071613_2ch City of Santa Rosa

11 Table 2-8. Summary of Residential Potable Unit Water Demand Factors (a,b), gallons/unit/day Land Use Designation Very Low Density Residential Low Density Residential Medium Low Density Residential Medium Density Residential Medium High Density Residential (c) (a) Rounded to the nearest one. (b) data obtained from Table 4 from the May 2008 City of Santa Rosa Water Model Update and Calibration - Development of Unit Water Demand Factors Memorandum data developed from WaterMeters_geocode_consumpt.shp and SR_parcels.shp provided by City staff. (c) Annual recycled water use was reviewed, but individual meter records were not specifically evaluated because recycled water use was a very small percentage of potable water use (less than one percent). o\c\405\ \e\t3\unitfactors Last Revised: City of Santa Rosa

12 Land Use Designation Very Low Density Residential Low Density Residential Medium Low Density Residential Medium Density Residential Medium High Density Residential (c) Average (2002 to 2012) Average of Years within One Standard Deviation Shaded cell and bold text indicate value that is within one standard deviation of the average value for that corresponding land use designation. (a) Rounded to the nearest one. (b) data obtained from Table 4 from the May 2008 City of Santa Rosa Water Model Update and Calibration - Development of Unit Water Demand Factors Memorandum data developed from WaterMeters_geocode_consumpt.shp and SR_parcels.shp provided by City staff. (c) Annual recycled water use was reviewed, but individual meter records were not specifically evaluated because recycled water use was a very small percentage of potable water use (less than one percent). Table 2-9. Evaluation of Average Residential Potable Unit Water Demand Factors (a,b), gallons/unit/day o\c\405\ \e\t3\unitfactors Last Revised: City of Santa Rosa

13 Chapter 2 Water Demands A comparison between the average unit water demand factor and the average unit water demand factor within one standard deviation indicates that the average unit water demand factors (including all available data from 2002 to 2012) are similar to the averages within one standard deviation, and inclusion of this entire data set would also capture some reduction in water use from more recent water conservation efforts. Accounting for water use reduction from water conservation in the recommended unit water demand factors would be reasonable as water conservation efforts must continue in the future due to compliance with SB 7. Therefore, the historical average of all available data (2002 to 2012) was subsequently used to develop the recommended residential unit water demand factors Non-Residential Water Demand Factors The water meter records linked to the City s parcel data were used to calculate non-residential unit water demand factors (af/ac/yr) by taking the total annual water demand by land use designation and dividing that demand by the associated total parcel acreage having water demand linked to it. Table 2-10 summarizes the new non-residential unit water demand factors calculated for 2006 to Non-residential unit water demand factors developed previously for 2002 to 2005 were also included for comparison. As shown in Table 2-10, additional land use designations have been included in the more recent unit water demand factor calculations for consistency with the City s General Plan. Consistent with the methodology used to develop the recommended residential unit water demand factors, the historical average of all available data was subsequently used to develop the recommended non-residential unit water demand factors Recommended Unit Water Demand Factors Table 2-11 presents a comparison between the new average unit water demand factors with previously developed average unit water demand factors. Average unit water demand factors were developed previously as part of the 2006 and were updated in a 2008 study 2 as part of the City s water system hydraulic model update and calibration project. A comparison of the residential unit water demand factors indicates that the new unit water demand factors are very similar to the previously developed factors. The new unit water demand factors were generally about 5 to 10 percent lower than the factors developed in the 2008 study. The accuracy of these factors could be improved by refining the average dwelling unit density used to calculate the factors. 2 City of Santa Rosa Water Model Update and Calibration Development of Unit Water Demand Factors Memorandum, West Yost Associates, May August 2014 o\c\405\ \wp\mp\071613_2ch City of Santa Rosa

14 Table Summary of Non-Residential Potable Unit Water Demand Factors (a,b), af/ac/yr Land Use Designation 2002 (c) 2003 (c) 2004 (c) 2005 (c) Average (d) Agriculture Low/Open Space Parks/Recreation (e) Mobile Home Park Business Park General Industry Light Industry LtInd/Med Residential Retail and Business Service Retail/Med Residential Office Office/High Residential Office/Med Residential Public/Institutional (e) Transit Village Medium Transit Village Mixed Use (a) Rounded to nearest tenth. (b) data obtained from Table 2 from the May 2008 City of Santa Rosa Water Model Update and Calibration - Development of Unit Water Demand Factors Memorandum data developed from WaterMeters_geocode_consumpt.shp and SR_parcels.shp provided by City staff. (c) data did not develop values for all land use designations in the City's current General Plan. (d) Includes data if available. (e) Annual recycled water use was reviewed, but individual meter records were not specifically evaluated because recycled water use was a very small percentage of potable water use (less than one percent). o\c\405\ \e\t3\unitfactors Last Revised: City of Santa Rosa

15 Land Use Designation New Average Unit Water Demand Factors Table Comparison of Potable Unit Water Demand Factors 2008 Study Unit Water Demand Factors (a) 2006 Study Unit Water Demand Factors (a) Difference (b) New Study Difference (b) New Study Percent Difference from 2008 Study Percent Difference from 2006 Study Residential gallons/unit/day gallons/unit/day gallons/unit/day gallons/unit/day gallons/unit/day Very Low Density % 5% Low Density % -15% Medium Low Density % -6% Medium Density % 6% Medium High Density (c) % -9% Non-Residential (d) af/ac/yr af/ac/yr af/ac/yr af/ac/yr af/ac/yr Retail and Business Service (e) % -15% Office (e) % -13% Business Park (e) % -30% Light Industry (f) % -55% General Industry (f) % 15% Public/Institutional (c) % -60% Parks/Recreation (c) % -91% (a) Data obtained from Table 5 from the May 2008 City of Santa Rosa Water Model Update and Calibration - Development of Unit Water Demand Factors Memorandum. (b) Previous unit water demand factor minus new unit water demand factor. (c) Annual recycled water use was reviewed, but individual meter records were not specifically evaluated because recycled water use was a very small percentage of potable water use (less than one percent). (d) Land use designations that were not evaluated in the 2006 and 2008 Studies were not included. (e) From Commercial designation in Table 3-7 in the June (f) Combined factor for Light and General Industry land use designations. o\c\405\ \e\t3\unitfactors Last Revised: City of Santa Rosa

16 Chapter 2 Water Demands A comparison of the non-residential unit water demand factors indicates that the new unit water demand factors are close to the previously developed factors, except for the Parks/Recreation factor. Most of the new unit water demand factors were generally about 10 to 15 percent lower than the factors developed in the 2008 study. The new unit water demand factor for Parks/Recreation is significantly lower than the 2008 study and discussions with City staff indicate that there have been efforts to reduce water use at the City s recreational facilities. This lower factor will continue to be recommended for consistency with the methodology used to develop the other factors. However, additional discussions with City staff indicate that water use at Parks/Recreation facilities may need to increase in the future to accommodate requests from the City s residents for greener recreational spaces (e.g., more grass and trees). Therefore, it is recommended that the City continue to monitor water use for Parks/Recreation land use to determine if a higher unit water demand factor is warranted in the future. Table 2-12 summarizes the recommended unit water demand factors. It should be noted that the actual water meter records used to develop the unit water demand factors are reflective of potable water use only, and do not account for the use of recycled water supply for exterior landscape irrigation. If the City were able to provide the recycled water meter records, more accurate water use factors could be determined, particularly for the Medium High Density Residential, Public/Institutional and Parks/Recreation land use designations. However, current records of recycled water use indicate that the recycled water usage is less than one percent of the City s potable water use and would not affect the water use factors significantly Projected Water Demands Future water demands were projected based on four distinct development categories: pending developments, intensification of Specific Plan Station Areas, private water systems, and vacant parcels. Each category is further discussed below, and Figure 2-4 provides a map of the projected future development locations from each category. Figure 2-5 shows the projected General Plan land use for private water system and vacant parcels. The projected timing of future water demands was developed based on discussions with City staff Pending Developments The City provided details regarding near-term pending developments, which included specific land use data such as square footage of non-residential properties and number of residential dwelling units for each pending development. Acreage for non-residential developments was calculated using Floor-to-Area Ratio (FAR) factors of 0.35 for retail and 0.50 for office land uses, respectively (based on data provided by the City). The recommended unit water demand factors were applied to the projected land uses for the pending developments to project the future water demand associated with these developments. The total projected buildout average day water demand for pending developments is 1.4 mgd. August 2014 o\c\405\ \wp\mp\071613_2ch City of Santa Rosa

17 Table Recommended Potable Unit Water Demand Factors Residential Land Use Designation Recommended Unit Water Demand Factor gallons/unit/day Very Low Density 630 Low Density 288 Medium Low Density 216 Medium Density 211 Medium High Density 145 Non-Residential af/ac/yr Agriculture 0.3 Low/Open Space 0.4 Parks/Recreation (a,b) 0.3 Mobile Home Park 1.3 Business Park 1.4 General Industry 2.3 Light Industry 0.9 LtInd/Med Residential 0.4 Retail and Business Service 1.7 Retail/Med Residential 1.8 Office 1.4 Office/High Residential 4.3 Office/Med Residential 2.0 Public/Institutional (a) 0.8 Transit Village Medium 1.1 Transit Village Mixed Use 3.5 (a) Annual recycled water use was reviewed, but individual meter records were not specifically evaluated because recycled water use was a very small percentage of potable water use (less than one percent). (b) Developed based on existing water meter record data. Discussions with City staff indicate that water use at Parks/Recreation facilities may need to increase in the future to accommodate requests from the City s residents for greener recreational spaces. City should continue to monitor water use for Parks/Recreation land use to determine if a higher unit water demand factor is warranted in the future. o\c\405\ \e\t3\unitfactors Last Revised: City of Santa Rosa

18 Chapter 2 Water Demands The timing of projected water demands from pending developments is expected to occur in the next several years. City staff provided information on near-term pending developments in construction; these developments were assumed to occur by The remaining pending developments were assumed to develop in the next five years (i.e., by 2018). Consequently, the projected average day water demand from pending developments by 2015 is 0.2 mgd with an additional 1.2 mgd by Intensification of Station Areas The City has two approved Specific Plans for the Downtown and North Santa Rosa Station Areas. 3 The Station Areas are currently developed, but the development is expected to intensify in the future due to proposed transit supportive development. Water demands due to intensification of the Station Areas were previously developed as a part of the Environmental Impact Report (EIR) and were subsequently used to estimate the projected water demands due to intensification. The projected buildout average day water demands from intensification of the Downtown and North Santa Rosa Station Areas are 1.1 mgd and 1.1 mgd, respectively. Consequently, the total projected buildout average day water demand for intensification of the Station Areas is 2.2 mgd. Since the Specific Plans provide a clearly defined plan for development, the timing of projected water demands from the Station Area Specific Plans is expected to occur by Private Water Systems There are parcels within the City s Urban Growth Boundary (UGB) that are served by private wells to provide either the total water supply or water solely for landscape irrigation. Water demands from these parcels served by private wells were included in the City s future water demand projection to develop a conservative water demand estimate in the event that the City will need to serve these water users at some future date. The parcels, acreage and land use in private water systems were determined by overlaying GIS data of the private water systems provided by the City onto the parcel data with General Plan land use. The recommended unit water demand factors were then applied to the resulting areas by land use designation to determine the associated water demand. The total projected buildout average day water demand for private water systems is 0.7 mgd. Since the timing of incorporating projected water demands from the private water systems into the City s existing water system is uncertain, it is assumed that they will occur at buildout (2035). 3 The City also has Southeast and Southwest Specific Area Plans, but these do not include Intensification plans. Projected demand increases in the Southeast and Southwest Specific Area Plans are included in the pending development, private water systems, and vacant parcel categories discussed in this chapter. August 2014 o\c\405\ \wp\mp\071613_2ch City of Santa Rosa

19 Chapter 2 Water Demands Figure 2-4 shows the potential future additional service area of Holland Heights Holland Drive southwest of Bennett Valley Road, and Bennett View Drive southwest of Bennett Valley Road which is currently served by a private water system. The City does not necessarily plan to incorporate these existing distribution facilities into the City s water distribution system. However, the City is prepared to provide water supply to this area at a future date if required/requested to do so by City Council, and therefore the projected water demand for this area is allocated in the future water system to several connection points along Bennett Valley Road Vacant Parcels Locations of existing vacant parcels were provided by the City. The vacant parcels file was first overlaid with the City s parcel data to incorporate the General Plan land use for each vacant parcel within the City s UGB. The vacant parcels file was further modified to remove any parcels that were already accounted for in the pending developments, intensification of the Station Areas and private water systems. Water demands for all the remaining vacant parcels within the UGB were then projected based on the recommended unit water demand factors. The projected buildout average day water demands from vacant parcels located inside the City Limits and outside of the City Limits are 2.9 mgd and 2.4 mgd, respectively. Consequently, the total projected buildout average day water demand for vacant parcels is 5.3 mgd. The timing of incorporating projected water demands from vacant parcels located inside the City Limits (into the City system) is assumed to occur between 2020 and Incorporating water demands for vacant parcels located outside the City Limits is assumed to occur at buildout (2035). Table 2-13 provides a summary of the calculations for the land use based water demand projections for the private water system and vacant parcels. To develop the total projected water demand, projected water demands from the four development categories described above were added to a baseline water demand of 20 mgd, which is equal to the City s average day water purchased/produced from 2002 to An historical average was used to represent the base water demand because it is consistent with the methodology used to develop unit water demand factors, and it is also more representative of historical water use trends. Table 2-14 presents the projected average day water demand by development category and assumed timing for each. The City s buildout average day water demand is projected to be 29.6 mgd based on the land use based water demand projection methodology described above. Figure 2-6 graphically presents the projected average day water demand for the City. As shown on Figure 2-6, significant development (5.1 mgd) is expected to occur by 2020 due to the development of vacant parcels and intensification of the Station Areas. This near-term growth appears aggressive and may need to be adjusted, but more refined timing of near-term development is not currently available. Therefore, for planning purposes, this aggressive nearterm growth will continue to be recommended. Additional development of the remaining vacant parcels and service to private water systems (4.5 mgd) is expected to occur between 2020 and The growth trend between 2020 and 2035 is more similar to the City s historical average day water demand. August 2014 o\c\405\ \wp\mp\071613_2ch City of Santa Rosa

20 Land Use Designation Residential Table Summary of Water Demand Projections for Private Water System and Vacant Parcels Private Water Systems (a) Vacant Inside City Limits (b) Area, acres Vacant Outside City Limits (b) Total Density, unit/ac Total Dwelling Units Recommended Unit Water Demand Factor gallons/unit/day Private Water Systems Vacant Inside City Limits Vacant Outside City Limits Very Low Density , , Low Density , , Medium Low Density , Medium Density , Medium High Density , Non-Residential af/ac/yr Low/Open Space Parks/Recreation Mobile Home Park Business Park General Industry Light Industry Retail and Business Service Retail/Med Residential Office Office/Med Residential Public/Institutional Transit Village Medium Total 659 2,282 1,717 4,658 14, Total with UAFW (c) (a) Source: WaterSystems_fromState_mod.shp, received from City staff. File was modified to include General Plan land use and only parcels inside the UGB were included. (b) Source: ExistingLandUse_Vacant.shp, received from City staff. File was modified to remove parcels that are located in pending developments, intensification and private water system areas. (c) Includes 7.3 percent UAFW. Projected Average Day Water Demand, mgd Total o\c\405\ \e\t3\unitfactors Last Revised: City of Santa Rosa

21 Table Average Day Water Demand Projections, mgd (a) Development Category Pending Developments Intensification Downtown Station Area (b) Intensification North Santa Rosa Station Area (c) Private Water Systems 0.7 Vacant Inside City Limits Vacant Outside City Limits 2.4 Subtotal Baseline Water Demand (d) Total (a) Includes 7.3 percent UAFW. (b) Source: Appendix G of Downtown Station Area Specific Plan Draft Environmental Impact Report, City of Santa Rosa and DCE, February (c) Source: Appendix D2 of North Santa Rosa Station Area Specific Plan Draft Environmental Impact Report, PMC, April (d) Based on historical average water purchased/produced from o\c\405\ \e\t3\unitfactors Last Revised: City of Santa Rosa

22 Chapter 2 Water Demands The following sections provides comparisons between the land use based water demand projection presented in this section and other water demand projections based on population or other previous studies Population Based Projections The current General Plan projects the City s population will reach 233,520 people within the Urban Growth Boundary at The 2010 UWMP derived population projections in 5-year intervals using a straight-line projection developed between 2000 and 2035 population estimates. Table 2-15 provides the projected water demand based on the 2035 General Plan population estimates and SB 7 per capita water use targets. The projected water demand based on population projections is estimated to be 29.7 mgd at Table Projected Water Demands Based on Population (a) (b) (c) (d) Year Projected Population (a) Water Demand, gpcd Projected Per Capita Projected Water Demand, mgd (b) , (c) , (d) , (d) , (d) , (d) 29.7 Source: 2010 UWMP, Table 2-2, June Includes unaccounted for water. Based on interim (2015) SB 7 per capita water use target. Based on final (2020) SB 7 per capita water use target Comparison of Water Demand Projections Table 2-16 provides a comparison of the projected buildout water demands using the land use and population based methodologies described above with previous studies. A review of these buildout water demand projections indicates that (1) there is a slight decreasing trend in the demand projections as estimates are refined through additional studies and (2) the land use based buildout water demand projection developed for this is almost identical to the more recent buildout water demand projection presented in the City s 2010 UWMP although different demand projection methodologies were used. August 2014 o\c\405\ \wp\mp\071613_2ch City of Santa Rosa

23 Table Comparison of Buildout Water Demand Projections (a) Date of Study Study Basis for Projection Projected Year in which Buildout Would Occur Projected Average Day Demand, mgd 2002 City of Santa Rosa Water Supply Analysis (West Yost) 2002 General Plan (Population) 2020 (b) Buildout (2027) (c) City of Santa Rosa Water Supply Analysis (West Yost) 2002 Land Use Background Report Buildout (2027) City of Santa Rosa 2005 Urban Water Management Plan (Maddaus) Water Accounts Buildout (~2028) City of Santa Rosa Water Master Plan Update (West Yost) Water Accounts City of Santa Rosa 2010 Urban Water Management Plan (West Yost & Maddaus) Population and Plumbing Code Implementation City of Santa Rosa Water Master Plan Update (West Yost) Land Use City of Santa Rosa Water Master Plan Update (West Yost) Population and SB 7 Targets (a) Data for 2002 to 2006 studies based on data presented in Table 3-10 from (b) Planning horizon of 2002 General Plan, through year (c) Estimated year of buildout of Urban Growth Boundary. o\c\405\ \e\t3\unitfactors Last Revised: City of Santa Rosa

24 Chapter 2 Water Demands Recommended Future Water Demand Projection It is recommended that the City adopt the land used based water demand projection for this because it is consistent with the projected water demand from the City s 2010 UWMP. In addition, with the land use based water demand projection, GIS parcel data can be used to spatially locate projected water demands for the hydraulic evaluation of the future water system. This would provide a more accurate future water system demand allocation into the City s hydraulic model. Therefore, the land use based water demand projection method described above will be utilized throughout the remainder of this. These projected future water demands are summarized in Table Table Summary of Recommended Water Demand Projections at Buildout Demand Condition Peaking Factor Buildout (2035) Water Demand, mgd Average Day Average Day During Maximum Month Maximum Day Peak Hour August 2014 o\c\405\ \wp\mp\071613_2ch City of Santa Rosa

25 Last Saved: 4/24/ :16:53 PM ddemaster; O:\Clients\405 City of Santa Rosa\ WMP Update\GIS\Figures\Fig 2-1 City and Service Area.mxd FIGURE 2-1 LEGEND City Limits City of Santa Rosa Water Service Area 0 5,000 Scale in Feet 10,000 EXISTING WATER SERVICE AREA DRAFT

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27 Figure 2-2. Historical Monthly Total Water Purchases and Groundwater Production 1,200 Sources: CSR_Use and Production Statistics_ CSR_ProdandUse_ xlsx, received from City staff on 8/29/ _Production and Use Statistics.pdf, received from City staff on 5/20/14. 1, Water Purchased/Produced, MG January February March April May June July August September October November December Month o\c\405\ \e\t3\historicaldata _DmdProj.xlsx Last Revised: 06/09/14 City of Santa Rosa

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29 Last Saved: 6/9/2014 3:55:32 PM ddemaster; O:\Clients\405 City of Santa Rosa\ WMP Update\GIS\Figures\Fig 2-4 Projected Demand Areas.mxd FIGURE 2-4 City of Santa Rosa AREAS WITH PROJECTED WATER DEMAND 0 2,500 5,000 Scale in Feet NOTES 1. Projected demand increases in the Downtown and North Santa Rosa Station Areas are included in the Intensification category in Chapter 2. LEGEND Pending Development Private Water System Parcel Vacant Parcel; Inside City Limits Vacant Parcel; Outside City Limits Holland Heights Downtown Station Area North Santa Rosa Station Area Southeast Area Plan Southwest Area Plan City Limits Urban Growth Boundary

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31 Last Saved: 6/17/2014 8:00:48 AM ddemaster; O:\Clients\405 City of Santa Rosa\ WMP Update\GIS\Figures\Fig 2-5 Projected LU.mxd FIGURE 2-5 City of Santa Rosa PROJECTED LAND USE FOR PRIVATE WATER SYSTEM AND VACANT PARCELS 0 2,500 5,000 Scale in Feet LEGEND Land Use Designation Very Low Density Residential Low Density Residential Medium Low Density Residential Medium Density Residential Medium High Density Residential Low/Open Space Parks/Recreation Mobile Home Park Business Park General Industry Light Industry Retail and Business Service Retail/Med Residential Office Office/Med Residential Public/Institutional Transit Village Medium Transit Village Mixed Use City Limits Urban Growth Boundary