SR nd Street SE to 112th Street SE (527 Widening) Mitigation Site WIN # A52720B USACE NWP (14)

Transcription

1 SR nd Street SE to 112th Street SE (527 Widening) Mitigation Site WIN # A52720B USACE NWP (14) Northwest Region 2016 MONITORING REPORT Wetlands Program Issued March 2017 Environmental Services Office

2 Author: Cyndie Prehmus Editor: Doug Littauer Contributors: Tatiana Dreisbach Jennie Husby Tom Mohagen Sean Patrick For additional information about this report or the WSDOT Wetlands Program, please contact: Doug Littauer, Wetlands Program WSDOT, Environmental Services Office P. O. Box 47332, Olympia, WA Phone: Monitoring reports are published on the web at:

3 SR nd Street SE to 112th Street SE Mitigation Site USACE NWP (14) General Site Information USACE NWP 14 Number WIN # Mitigation Location LLID Number A52720B Construction Date 2006 Monitoring Period Year of Monitoring 10 of 10 Type of Impact Area of Project Impact 1 Type of Mitigation Planned Area of Mitigation 1 South of Everett and north of Mill Creek, Snohomish County Floodplain site: Shoreline site: Wetland 0.32 acre Wetland Establishment Floodplain site: 0.5 ac Shoreline site: 0.31 ac Wetland Enhancement Shoreline: 0.26 acres 1 Impact and mitigation numbers sourced from USACE NWP 14 Permit Number (USACE 2005) and from 25 June 2005 letter from WSDOT to Sandra Manning.

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5 Summary of Monitoring Results and Management Activities (2016) 80% cover of native vegetation Performance Standards No more than 20% cover of invasive species The created wetlands will have soils saturated to the surface for a minimum of 12.5% of the growing season Soil in the wetlands will meet hydric soil criteria or be functioning as a hydric soil Document wildlife use of habitat and structures 2016 Results 2 Management Floodplain/Wetland Site Shoreline Enhancement Area Activities 90-95% cover (qualitative) <1 % cover (qualitative) Present Present Wildlife documented in prior reports 93% cover (CI 95% = 89-97%) < 5% cover (qualitative) Present Present Wildlife documented in prior reports Both sites: weed control Report Introduction This report summarizes final-year (Year-10) monitoring activities at the 527 Widening Wetland and Shoreline Mitigation Site. Included are a site description, the performance standards, an explanation of monitoring methods, and an evaluation of site success. Monitoring activities included vegetation surveys, photo-documentation, assessments of wetland hydrology, and a wetland delineation. Hydrology visits occurred on March 11, March 22, and April 5, 2016, and vegetation data was collected on December 13 and 14, Estimated values are presented with their corresponding statistical confidence interval. For example, 93% cover (CI 80% = 89-97% cover) means we are 80% confident that the true cover value is between 89% and 97%. 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

6 What is the 527 Widening Wetland and Shoreline Mitigation Site? The 1.3-acre floodplain/wetland mitigation site (Figure 1) contains 0.5 acre of newly established forested wetland and 0.01 acre of wetland enhancement and is located approximately one mile southeast of Silver Lake in Snohomish County. Compensation for project impacts also includes 2,700 linear feet of enhancement (consisting of 0.26 acre of wetland enhancement and 0.31 ac of wetland establishment) along the north and northeastern shoreline of Silver Lake (Figure 2). These sites were established and enhanced to compensate for the loss of 0.32 acre of wetlands due to road improvements along SR 527. The floodplain/wetland mitigation site and shoreline enhancement areas are designed to minimize erosion, enhance public access to Silver lake, enhance fish passage and fish habitat, enhance wildlife habitat, and improve water quality. Figure 1 Site Sketch The 527 Widening Floodplain/Wetland Mitigation Site includes a forested wetland community. The site contains three bays that provide flood storage for Silver Lake Outlet Creek. The bays connect to the Silver Lake Outlet Creek via narrow return-flow channels that extend into the center of the three bays. Log weirs and flow control berms line the channels. 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

7 Figure 2 Shoreline Wetland Enhancement Area Sketch The 527 Widening Silver Lake Shoreline Enhancement Area contains approximately 2,700 linear feet of enhancement and creation along the north and northeastern shores of Silver Lake. Appendix 1 shows the floodplain/wetland mitigation site as-built planting plan (WSDOT 2003) and the shoreline enhancement area planting plans (WSDOT 2001). Appendix 2 contains site directions Widening Wetland and Shoreline Enhancement Annual Monitoring Report

8 What are the performance standards for this site? The following performance standards apply to both the floodplain/wetland mitigation site and the shoreline enhancement area. Only five years of performance standards were written for these sites, but as per the USACE permit (USACE 2005), reporting is required through Year 10. The Year 5 performance standards are, therefore, considered to be the final performance standards and are being applied to Years 7 and 10 as well. Performance Standard 1 Starting in the third-year, performance will be based on percent cover instead of survival. The performance standard for native vegetation cover will be 60 percent cover in the third year and 80 percent cover in the fifth-year. Performance Standard 2 Invasive species will be controlled by mechanical and/or hand labor removal methods with the aid of weed control materials. The planting contractor will warrant control of invasive species for one year after completion of planting. WSDOT will retain a maintenance landscape contractor to control invasive species after the second year. If invasive control fails to keep invasive plants below 20 percent, additional invasive plant control measures will need to be implemented to achieve the performance goal that calls for less than 20 percent invasives. Invasive plants to be controlled are shown in Appendix 3, Table 4. The dominant invasive plants on this project are: Himalayan blackberry (Rubus laciniatus) Reed canarygrass (Phalaris arundinacea) Japanese knotwood (Polygonum cuspidatum) Scott s broom (Cytisus scoparius) Performance Standard 3 The created wetlands will have soils saturated to the surface for a minimum of 12.5 percent of the growing season (approximately 26 days during March to October) in a typical hydrologic year. Performance Standard 4 Soil in the wetlands will meet hydric soil criteria or be functioning as a hydric soil as described in the Washington State Wetlands Identification and Delineation Manual (Ecology 1997) after five years. 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

9 Performance Standard 5 The wetland mitigation and buffer areas will create additional wildlife habitat and it is expected that wildlife numbers and diversity will increase. Nesting boxes will be added to the Silver Lake Shoreline for chickadee, wren, swallow and flicker. Small mammal habitat brush piles will also be added to the offsite floodplain/wetland facility. The proposed design for the offsite floodplain/wetland facility will also add structural and species diversity, winter cover, and shallow areas for invertebrates, and habitat improvements for fisheries in the Silver Lake Outlet Creek. The performance standard will be to verify use of nesting boxes and small mammal brush piles and to document use of the overall site by various bird and mammal species. 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

10 How were the performance standards evaluated? To evaluate vegetative cover, a 780-meter baseline was established parallel to the lakeshore in the shoreline enhancement area (Figure 3). Twenty-six transects were placed perpendicular to the baseline using a systematic random sampling method. The line-intercept method was used to estimate the cover of native vegetation (Performance Standard 1). Twenty-five four-meter-long line-segment sample units were randomly positioned along the transects. WSDOT staff collected hydrology data (Performance Standard 3) and soil profile information (Performance Standard 4) using methods described in the Corps of Engineers Wetlands Delineation Manual (Environmental Laboratory 1987) and the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0) (USACE 2010). Visual estimates were used to assess the cover of invasive species (Performance Standard 2). Wildlife usage has been documented in prior reports (Performance Standard 5). For additional details on the methods, see the WSDOT Wetland Mitigation Site Monitoring Methods Paper (WSDOT 2008). Figure 3 Shoreline Site Sampling Design (2013) The floodplain site was delineated in 2015 and the shoreline site was delineated in 2016 (see Appendix 4). 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

11 Are the sites successful? The native plant communities at both the floodplain/wetland mitigation site and the shoreline enhancement area have developed into dense, diverse native communities. Cover of invasive species on both sites remains low, and wildlife has been documented using both sites. Both sites meet all of the final-year performance standards. The floodplain/wetland site previously met all of its final-year vegetative performance standards, and on April 1, 2013; a request to discontinue all quantitative vegetation sampling on this site was sent to the U.S. Army Corps of Engineers (USACE). This request was accepted on June 24, Widening Wetland and Shoreline Enhancement Annual Monitoring Report

12 Results for Performance Standard 1 (80% cover of native vegetation): Shoreline: 93% cover (CI95% = 89-97%) by woody species (Photo 1). Due to late sampling, herbaceous vegetation was not included in the sample design. Willows provide about a third of the cover. Sweet gale (Myrica gale), hardhack (Spiraea douglasii), Nootka rose (Rosa nutkana) and Pacific ninebark (Physocarpus capitatus) each provide in the range of 10 percent absolute cover. Several other native woody species provide less than 10 percent cover. Wetland: Qualitatively estimated at percent cover with three layers to the canopy (tree layer, shrub layer, herbaceous understory) (Photo 2). Results for Performance Standard 2 (No more than 20% cover of invasive species): Photo 1 Shoreline woody cover (Dec 2016) Shoreline: Qualitatively, cover by invasive species was estimated to be less than one percent cover, consisting of reed canarygrass, Himalayan blackberry, and paleyellow iris. Cover by invasive species during the growing season would have been higher, but likely not more than five percent. In July 2015, this area was estimated to have less than five percent cover by reed canary grass, purple loosestrife and Himalayan blackberry. Wetland: Qualitatively, cover by invasive species was estimated to be less than one percent cover, consisting of reed canary grass, cutleaf blackberry, and Himalayan blackberry. In July 2015, this area was estimated to have one percent cover by reed canary grass and Himalayan blackberry. Photo 2 Woody cover in the Floodplain wetland (9 March 2016) 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

13 Results for Performance Standard 3 (The created wetlands will have soils saturated to the surface for a minimum of 12.5 percent of the growing season): Hydrology monitoring was conducted in 2016 on March 9, March 22, and April 5 at the floodplain/wetland site. During each of the three visits either inundation or saturation to the soil surface was observed in the intended wetland areas (Photo 3). Results for Performance Standard 4 (Soil in the wetlands will meet hydric soil criteria or be functioning as a hydric soil): During the April 2015 delineation of the Floodplain site, soils were too wet to excavate a pit. These soils meet definition of hydric soil due to prolonged inundation. Photo 3 Surface saturation (March 2016) Results for Performance Standard 5 (Document wildlife use of habitat and structures): Evidence of the use of habitat structures has been documented in prior reports. What is planned for this site? Closeout will be requested for both sites in Spring Widening Wetland and Shoreline Enhancement Annual Monitoring Report

14 Appendix 1 As-Builts Floodplain/Wetland Mitigation Site (WSDOT 2003) 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

15 Silver Lake Shoreline Enhancement Area Planting Plans (WSDOT 2001) 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

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22 Appendix 2 Photo Points Floodplain/Wetland Mitigation Site Photo Points The photographs below were taken from permanent photo-points on December 14, 2016 and document current site development. 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

23 Photo Point 1a Photo Point 1c Photo Point 1b Photo Point 1d 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

24 Photo Point 2 Photo Point 4 Photo Point Widening Wetland and Shoreline Enhancement Annual Monitoring Report

25 Shoreline Mitigation Site Photo Points The photographs below were taken from permanent photopoints on December 14 th, 2016and document current site development. Photo Point 1 Photo Point Widening Wetland and Shoreline Enhancement Annual Monitoring Report

26 Photo Point 3 Photo Point 5 Photo Point 4 Photo Point Widening Wetland and Shoreline Enhancement Annual Monitoring Report

27 Photo Point 7 Driving Directions: To get to the Wetland Site from I-5 north, take Exit 186. Turn right and follow SR 96. Turn left at 19th Avenue Southeast/Bothell Everett Hwy/SR 527. Turn right at124th Street Southeast. Turn right at 25th Ave SE. The site is at the end of this road to the south behind a small chain-link fence. The Shoreline Enhancement Area is immediately west of SR 527 approximately one mile north of the SR 96/SR 527 interchange. 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

28 Appendix 3 Data Tables and Hydrology Well Locations Normal conditions were present for the three months before the hydrology field visits based on the data in Table 2 (page 26). Precipitation observed at the Everett station in the 10 days prior to the field work was heavy in early March, moderate in mid- March and light in early April based on Table 3 (page 27). Table 1. Hydrology Observations Date March 9, 2016 March 22, 2016 April 5, 2016 Surface Observations Shallow inundation or surface saturation covering about 3/4 of the intended wetland area. Inundation in the channels, creek is flowing, saturation near the edge of creek. Less water on site than previous visits, however there is still inundation in the channels and surface saturation throughout. Well ID # Water Level (inches below soil surface) 1 3" 2 1" 3 5" 1 6.5" 2 1" 3 5.5" 1 4" 2 3.5" 3 5.5" 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

29 Pit 1 Pit 2 Pit 4 Pit 5 Pit 6 Pit Widening Wetland and Shoreline Enhancement Annual Monitoring Report

30 Table 2. Comparison of Observed and Normal Precipitation (NRCS 1997) Monthly precipitation data for Everett, Washington. Long-term rainfall records a Month 3 yrs. in 10 less than Average 3 yrs. in 10 more than Rain fall a Condition dry, wet, normal b Condition Value Month weight value Product of previous two columns 1 st prior month Mar W nd prior month Feb N rd prior month Jan W Sum 14 a NRCS 2016 b Conditions are considered normal if they fall within the low and high range around the average. Note: If sum is Condition value: 6-9 then prior period has been Dry (D) =1 drier than normal Normal (N) = then period has been Wet (W) =3 normal then period has been wetter than normal Conclusions: Normal precipitation conditions were present leading up to the hydrology field visits. 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

31 Table 3. Daily Precipitation 10 days preceding field work, Everett, Washington Date (2015) Prior to March 11 visit Prior to March 22 visit Prior to April 5 visit Daily Precipitation (inches) a Date (2015) Daily Precipitation (inches) a Date (2015) Daily Precipitation (inches) a March March April March March April March 8 T March 19 T April 2 T March March April March March March March March March March March March March March March March March March March March March a NRCS 2016 Total: 2.91 Total: 1.21 Total: Widening Wetland and Shoreline Enhancement Annual Monitoring Report

32 Table 4. Non-native invasive species 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

33 Appendix 4 Delineation Report Place holder 527 Widening Wetland and Shoreline Enhancement Annual Monitoring Report

34 Literature Cited 1. Environmental Laboratory Corps of Engineers wetlands delineation manual. Vicksburg (MS): US Army Engineer Waterways Experiment Station. Technical Report Y Available at: 2. [USACE] US Army Corps of Engineers Department of the Army Nationwide Permit 14 Number [USACE] US Army Corps of Engineers Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0), Wakeley JS, Lichvar RW, Noble CV, editors. Vicksburg (MS): US Army Engineer Research and Development Center. ERDC/EL TR Available at: 4. [WSDOT] Washington State Department of Transportation SR 527 Widening Shoreline Planting Plans (Plan Sheets HP2 HP8). 5. [WSDOT] Washington State Department of Transportation Final Detailed Wetland and Stream Mitigation Plan SR nd St. SE to 112 th St. SE Widening. Seattle (WA): Washington State Department of Transportation, Northwest Region. 6. [WSDOT] Washington State Department of Transportation SR nd St. SE to 112 th St. SE Widen to Five Lanes 25 th Ave. Mitigation Site As-built Planting Plan. 7. [ WSDOT] Washington State Department of Transportation WSDOT Wetland Mitigation Site Monitoring Methods Widening Wetland and Shoreline Enhancement Annual Monitoring Report