SR 520 Medina to SR 202 Eastside Transit and HOV (Yarrow Creek Wetland) Mitigation Site USACE IP NWS-2009-562 Northwest Region 2018 MONITORING REPORT Wetlands Program Issued March 2019 Environmental Services Office
Author: Jennie Husby Editor: Kristen Andrews Contributors: Kristen Andrews For additional information about this report or the WSDOT Wetlands Program, please contact: Kristen Andrews, Wetlands Program WSDOT, Environmental Services Office P. O. Box 47332, Olympia, WA 98504 Phone: 360-570-2588 E-mail: Kristen.Andrews@wsdot.wa.gov Monitoring reports are published on the web at: http://www.wsdot.wa.gov/environment/technical/disciplines/wetlands/monitoringreports
SR 520 Medina to SR 202 Eastside Transit and HOV (Yarrow Creek Wetland) Mitigation Site USACE IP NWS-2009-562 USACE IP Ecology WQC 7718 Mitigation Location General Site Information NWS-2009-562 LLID Number 1221986476402 Construction Date 2014-2015 Monitoring Period 2016-2025 Year of Monitoring 3 of 10 Area of Project Impact 1 Type of Mitigation Planned Area of Mitigation 2 South side of SR 520, east of Bellevue Way Northeast, Bellevue, WA 6.78 acres Wetland Establishment Wetland Rehabilitation 0.52 acre 0.63 acre 1 Impact acreage was referenced from the SR 520 Eastside Transit Yarrow Creek Compensatory Mitigation Site Wetland Mitigation As-built Report (WSDOT 2015). 2 Mitigation acreages were referenced from the Final Wetland Mitigation Report Medina to SR 202: Eastside Transit and HOV Project (WSDOT 2010). Additional mitigation acreage provided at the 520 Evans Creek Mitigation Site.
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Summary of Monitoring Results and Management Activities (2018) Performance Standards (Year 3) 2018 Results 3 Management Activities Wetland Hydrology Four wetland woody plants/100ft 2 in the PSS/PFO rehabilitated wetland Present (see Appendix 3, Tables 1 and 2) >4 plants/100ft 2 (qualitative) 50% cover emergent native wetland vegetation in the streamside planting area 67% cover (CI 80%= 54-80%) No Washington State or King County-listed Class A noxious weeds across the site Control of King County-listed Class B and C weeds across the site Less than 25% cover King County non-designate noxious weeds in the rehabilitated wetlands and riparian uplands Four native woody plants/100ft 2 in the upland buffer Less than 25% cover King County non-designate noxious weeds in the upland buffer Performance Standards (Year 10) None observed purple loosestrife (Lythrum salicaria) observed and reported for control <10% cover (qualitative) >4 plants/100ft 2 (qualitative) <5% cover (qualitative) Weed control activity occurred across the site on 6/12, 7/26, and 8/13 in 2018 70% cover native woody species in the PSS/PFO rehabilitated wetland 76% cover (CI 80%= 68-84%) 50% cover emergent native wetland vegetation in the streamside planting area 67% cover (CI 80%= 54-80%) 50% cover native woody species in the upland buffer 72% cover (CI 80%= 64-79%) 3 Estimated values are presented with their corresponding statistical confidence interval. For example, 67% cover (CI 80% = 54-80%) means we are 80% confident that the true cover value is between 54% and 80%. 520 Yarrow Creek Wetland 1 2018 Annual Monitoring Report
Report Introduction This report summarizes third-year (Year 3) monitoring activities at the 520 Yarrow Creek Wetland Mitigation Site. Included are a site description, the performance standards, an explanation of monitoring methods, and an evaluation of site development. Monitoring activities included vegetation surveys and photo-documentation on August 6-8, and assessments of wetland hydrology on March 6, March 21, and April 4 in 2018. 520 Yarrow Creek Wetland 2 2018 Annual Monitoring Report
What is the 520 Yarrow Creek Wetland Mitigation Site? This 3.1-acre mitigation site (Figure 1) is a combination of rehabilitated and restored/newly established wetland located on the southwest side of SR 520, east of Bellevue Way Northeast. This site partially compensates for the loss of 6.78 acres of wetlands due to road improvements along SR 520. The realigned channel, re-connected floodplain, and expanded wetland area are designed to provide an increase in water quality, hydrologic, and habitat functions. Figure 1 Site Sketch The 520 Yarrow Creek Mitigation Site contains scrub-shrub wetland and upland buffer areas along a realigned section of Yarrow Creek. Emergent plantings were included along the banks of Yarrow Creek and in micro-depressions scattered throughout the scrub-shrub area. Appendix 2 includes site directions. 520 Yarrow Creek Wetland 3 2018 Annual Monitoring Report
What are the performance standards for this site? Year 3 Performance Standard 1 The soils in the rehabilitated wetland will be saturated to the surface, or standing water will be present within 12 inches of the surface for at least four consecutive weeks (10 percent) of the growing season in years when rainfall meets or exceeds the 30-year average. Performance Standard 2 Native, wetland (facultative and wetter) woody species (planted and volunteer) will achieve an average density of at least four plants per 100 square feet in the scrub-shrub and forested communities of the rehabilitated wetland. Performance Standard 3 In the streamside planting area, emergent native vegetation (planted and volunteer) will provide at least 25 percent cover. Gravel stream bed areas will not be included in the cover assessment. Performance Standard 4 Washington State and King County-listed Class A noxious weeds identified on the site shall be eradicated. Performance Standard 5 King County-listed Class B and C weeds identified on the site shall be controlled. Control of noxious weeds means to prevent all seed production and to prevent the dispersal of all propagative parts capable of forming new plants. Performance Standard 6 Noxious weeds listed by King County as non-designate including reed canarygrass (Phalaris arundinacea), non-native blackberries (Rubus species), and Scotch broom (Cytisus scoparius) will not exceed 25 percent aerial cover in rehabilitated wetlands and riparian uplands. Performance Standard 7 Native woody species (planted and volunteer) will achieve an average density of at least four plants per 100 square feet in the upland buffer. 520 Yarrow Creek Wetland 4 2018 Annual Monitoring Report
Performance Standard 8 Noxious weeds listed by King County as non-designate including reed canarygrass, non-native blackberries, and Scotch broom will not exceed 25 percent aerial cover in buffers. Year 10 Performance Standard 9 Aerial cover of native woody species will be at least 70 percent in the scrub-shrub and forested communities in the rehabilitated wetland. Desirable native species colonizing portions of the site will be included in the aerial cover. Performance Standard 10 In the streamside planting area, emergent native vegetation (planted and volunteer) will provide at least 50 percent cover. Gravel stream bed areas will not be included in the cover assessment. Performance Standard 11 Aerial cover of native woody species will be at least 50 percent in the upland buffer. Appendix 1 shows the as-built planting plan (Gage 2015). 520 Yarrow Creek Wetland 5 2018 Annual Monitoring Report
How were the performance standards evaluated? WSDOT staff collected hydrology data using methods described in the Corps of Engineers Wetlands Delineation Manual (Environmental Laboratory 1987), Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0) (USACE 2010). Shallow groundwater monitoring wells were installed following the Corps of Engineers guidance (USACE 2005) to evaluate groundwater during the growing season (Performance Standard 1). Wells one through three were observed on three separate visits and Wells four and five were fitted with Hobo data loggers (See Appendix 3). Appendix 3, Table 5 documents the sample method used for all of the remaining performance standards (PS) as required by the mitigation plan. For additional details on the methods see the WSDOT Wetland Mitigation Site Monitoring Methods Paper (WSDOT 2008). Figure 2 Site Sampling Design (2018) Placement of Baseline: The main baseline as placed west to east along the north side of the site. The riparian baseline was placed along emergent pockets in the riparian zone (only on the west side of the site due to deep inundation on the rest of the site). Main Baseline: Length 290m Transects 1-15 Riparian Baseline: 57m Transects 1-7 520 Yarrow Creek Wetland 6 2018 Annual Monitoring Report
How is the site developing? This site is developing faster than expected, and meeting all final-year (Year 10) performance standards in Year 3. Cover of native woody and herbaceous plant species is high. Cover of invasive species is low. The purple loosestrife observed during monitoring was removed and will continue to be targeted for control in the future. Beaver altered the hydrology on site, creating areas with deep inundation. So far, vegetation die-off due to inundation is low, and desired wetland hydrology is present. Water quality and wildlife habitat functions have improved. Coyote scat and four species of birds were observed at the time of monitoring. 520 Yarrow Creek Wetland 7 2018 Annual Monitoring Report
Results for Performance Standard 1 (Wetland Hydrology): Wetland hydrology is present across most of the site (Appendix 3, Tables 1, 2, and 3). A small portion of the intended wetland around Well 1 (Appendix 1) was dry, however 80-95 percent of the site was saturated or inundated on all three hydrology visits. Beaver have influenced the hydrology, creating areas of deep inundation (Photo 1). Results for Performance Standard 2 and 9 (Four wetland woody plants/100ft 2 in the PSS/PFO rehabilitated wetland; 70% cover native woody species in the PSS/PFO rehabilitated wetland): Density of native woody species is qualitatively estimated at greater than four plants/100ft 2 (Photo 2). Cover of native woody species in the scrub-shrub/forested wetland is estimated at 76% (CI80%= 68-84%). This exceeds the finalyear performance standard target. Dominant species include red alder (Alnus rubra), redosier dogwood (Cornus alba), Pacific willow (Salix lasiandra), and Sitka willow (Salix sitchensis). Photo 1 Beaver dam in the wetland (August 2018) Photo 2 520 Yarrow Creek Wetland 8 2018 Annual Monitoring Report
Density in the PSS/PFO (August 2018) Results for Performance Standard 3 and 10 (50% cover emergent native wetland vegetation in the streamside planting area): Cover of emergent wetland vegetation is estimated at 67% (CI80%= 54-80%) (Photo 3). This exceeds the final-year performance standard target. Dominant species include rice cutgrass (Leersia oryzoides), small-fruited bulrush (Scirpus microcarpus), woolgrass (Scirpus cyperinus), and soft rush (Juncus effusus). Results for Performance Standard 4 (No Washington State or King County-listed Class A noxious weeds across the site): No Class A noxious weeds observed. Results for Performance Standard 5 (Control of King County-listed Class B and C weeds across the site): Photo 3 Emergent cover in the streamside planting area (August 2018) Purple loosestrife, a King County-listed Class B designate, was observed scattered in small amounts throughout the wetland. 520 Yarrow Creek Wetland 9 2018 Annual Monitoring Report
Results for Performance Standard 6 (Less than 25% cover King County non-designate noxious weeds in the rehabilitated wetlands and riparian uplands): Cover of non-designate noxious weeds in the wetland and riparian uplands is qualitatively estimated at less than 10 percent. This is below the performance standard threshold. Species observed include reed canarygrass (Phalaris arundinacea), Himalayan blackberry (Rubus armeniacus), bull thistle (Cirsium vulgare), Canada thistle (Cirsium arvense), paleyellow iris (Iris pseudacorus), and cutleaf blackberry (Rubus laciniatus). Results for Performance Standard 7 and 11 (Four native woody plants/100ft 2 in the upland buffer; 50% cover native woody species in the upland buffer): Density of native woody species in the upland buffer is qualitatively estimated at greater than four plants/100ft 2 (Photo 4). Cover of native woody species is estimated at 72% (CI80%= 64-79%). This exceeds the final-year performance standard target. Dominant species include Nootka rose (Rosa nutkana), snowberry (Symphoricarpos albus), Pacific ninebark (Physocarpus capitatus), and red alder. Photo 4 Woody cover in the upland buffer (August 2018) What is planned for this site? Weed control will continue in 2019. Results for Performance Standard 8 (Less than 25% cover King County non-designate noxious weeds in the upland buffer): Cover of non-designate noxious weeds in the upland buffer is qualitatively estimated at less than five percent. This is below the performance standard threshold. Species observed include Scotch broom, cutleaf blackberry, Himalayan blackberry, bull thistle, and Canada thistle. 520 Yarrow Creek Wetland 10 2018 Annual Monitoring Report
Appendix 1 As-built Planting Plan with Photo Point Locations (from Gage 2015) 520 Yarrow Creek Wetland 11 2018 Annual Monitoring Report
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Appendix 2 Photo Points The photographs below were taken from permanent photo-points on August 8, 2018 and document current site development. Photo Point 1 Photo Point 2a Photo Point 2b Photo Point 2c 520 Yarrow Creek Wetland 15 2018 Annual Monitoring Report
Photo Point 3 Driving Directions: From Olympia, follow I-5 north, then take I-405 north to Bellevue. Take SR 520 West, then the 108th Avenue Northeast exit. There is no parking at the site. To drive by the site, take a left on 108th Avenue Northeast (which turns into 112th Avenue Northeast), travel under SR 520 and then get onto the onramp for SR 520 East. Halfway through the onramp, the site will be on the left. Parking can be arranged at the WSDOT maintenance facility on the north side of SR 520 at 10833 Northrup Way. 520 Yarrow Creek Wetland 16 2018 Annual Monitoring Report
Appendix 3 Ground Monitoring Well Map and Data Tables Ground Monitoring Well Locations 520 Yarrow Creek Wetland 17 2018 Annual Monitoring Report
Table 1. Hydrology Observations Date Surface Observations Well # Water Level (inches below soil surface) March 6, 2018 March 20, 2018 April 2, 2018 Beaver dam, sheet flow and deep ponding on east side of site 95% of the site behind the beaver dam is inundated; sheet flow extending away from the dam; past the dam on the west side of the creek predominantly dry; saturated on the east side 80% of the site is inundated or saturated; sheet flow from the beaver dam reaches just beyond well 5; mainly small portions on the west side of creek with no surface water 1 0 2 1.5 3 inundated 1 Dry to bottom of well 2 1 3 inundated 1 17.5 2 1 3 inundated 520 Yarrow Creek Wetland 18 2018 Annual Monitoring Report
Table 2. 520 Yarrow Creek Wetland 19 2018 Annual Monitoring Report
Table 3. 520 Yarrow Creek Wetland 20 2018 Annual Monitoring Report
Table 4. Comparison of Observed and Normal Precipitation (NRCS 2015) Monthly precipitation data for Seattle, 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 Feb 2.41 3.65 4.38 2.45 N 2 3 6 2 nd prior month Jan 4.09 5.35 6.22 7.33 W 3 2 6 3 rd prior month Dec 3.69 5.49 6.56 4.67 N 2 1 2 Sum 14 a NRCS 2018 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) =2 10-14 then period has been Wet (W) =3 normal 15-18 then period has been wetter than normal Conclusions: Normal precipitation conditions were present leading up to the hydrology field visits. 520 Yarrow Creek Wetland 21 2018 Annual Monitoring Report
Table 5. Sampling Methodology Attribute Target population Zone PS 2 PS 3 PS 4 PS 5 PS 6 PS 7 PS 8 PS 9 PS 10 PS 11 Presence/ Presence/ Density Cover absence absence Cover Density Cover Cover Cover Cover King King Class B County County Native Class A and C nondesignate Native non- Native Native woody Native herb noxious noxious woody designate woody Native herb woody species species weeds weeds weeds species weeds species species species Streamside planting area Entire site Entire site wetland and riparian uplands Upland buffer Upland buffer PSS/ PFO Streamside planting area SU width 1m 1m Points per SU 20 20 Total # of SU 7 14 7 12 Upland buffer PSS/PFO Sample Lineintercept method Qualitative Point-frame Qualitative Qualitative Qualitative Qualitative Qualitative Point-frame SU length 1m 10m 1m 5m Lineintercept 520 Yarrow Creek Wetland 22 2018 Annual Monitoring Report
Literature Cited 1. [Ecology] Washington State Department of Ecology. 2010. 401 Water Quality Certification Order Number 7718. 2. Gage, Jon. 2015. SR 520 Eastside Transit Yarrow Creek Compensatory Mitigation Site Wetland Mitigation As-built Report [Memorandum]. Bellevue (WA): David Evans and Associates, Inc. 3. [NRCS] Natural Resource Conservation Service. 2015. Hydrology Tools for Wetland Identification and Analysis. Chapter 19 in Part 650 Engineering Field Handbook. Pages 19-85 through 19-89. US. Department of Agriculture, NRCS. Available from: https://directives.sc.egov.usda.gov/opennonwebcontent.aspx?content=37808.wba 4. [USACE] US Army Corps of Engineers. 2005. Technical Standard for Water-Table Monitoring of Potential Wetland Sites. ERDC TN-WRAP-05-2. Available at http://www.wsdot.wa.gov/sites/default/files/2017/07/24/env-wet- WaterTableTechStds.pdf 5. [USACE] US Army Corps of Engineers. 2010. 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-10-3. Available at:https://www.usace.army.mil/missions/civil-works/regulatory-program-and-permits/reg_supp/ 6. [USACE] US Army Corps of Engineers. 2011. Department of the Army Individual Permit Number NWS-2009-562. 7. [WSDOT] Washington State Department of Transportation. 2008. WSDOT Wetland Mitigation Site Monitoring Methods. http://www.wsdot.wa.gov/nr/rdonlyres/c211ab59-d5a2-4aa2-8a76-3d9a77e01203/0/methodswhitepaper052004.pdf 8. [WSDOT] Washington State Department of Transportation. 2010. Final Wetland Mitigation Report Medina to SR 202: Eastside Transit and HOV Project. Seattle (WA): HDR Engineering, Inc. 520 Yarrow Creek Wetland 23 2018 Annual Monitoring Report