I-405 Bellevue to Lynnwood Improvement Project Mitigation Sites (Yarrow Creek Farms, C28, and Sammamish River Mitigation Sites)

USACE NWS-2007-1711

Northwest Region

2018 MONITORING REPORT

Wetlands Program

Issued March 2019

Environmental Services Office

Author: Trace McKellips

Editor: 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: [email protected]

Monitoring reports are published on the web at: http://www.wsdot.wa.gov/environment/technical/disciplines/wetlands/monitoring- reports

405 Yarrow Creek Farms, C28, and Sammamish River Mitigation Sites USACE NWS-2007-1711 General Site Information USACE NWP 14 NWS-2007-1711

Sammamish River: South bank of the Sammamish River, downstream of the confluence with Little Bear Creek, city of Bothell Mitigation Location Stream C28: Downstream of I-405 on an unnamed tributary to Juanita Creek Yarrow Creek: East side of I-405 south of Bridle Trails State Park LLID Number 1221986476401 Construction Date 2013 Monitoring Period 2014-2018 Year of Monitoring 5 of 5

Type of Impact Yarrow Creek Stream C28 Sammamish River

Area of Stream 0.21 acre 0.40 acre 0.91 acre Buffer Impact1 Type of Mitigation Stream Buffer Enhancement Planned Area of 0.65 acre 0.42 acre 0.10 acre Mitigation2

1 Impact numbers sourced from Stream Mitigation Report I-405, Bellevue to Lynnwood Improvement Project (WSDOT, 2013). 2 Mitigation numbers sourced from Stream Mitigation Report I-405, Bellevue to Lynnwood Improvement Project (WSDOT, 2013).

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Summary of Monitoring Results and Management Activities (2018)

Performance Standards 2018 Results3 Management Activities Sammamish River: Native woody plantings are estimated at 97% survival (CI80% = 95-100%).

80% native planting survival Stream C-28: Native woody plantings are estimated at 99% survival (CI % = 98-100%). 80

Yarrow Creek Farm: Native woody survival is estimated at 100% (CI80% = 99-100%). Sammamish River: This planting area is surrounded by invasive knotweed and nonnative blackberry species. They are encroaching from the edge of the site, particularly the eastern edge. However, cover of invasive species within the planting area is low, estimated at 3-5%. Manual and herbicide weed

control on a bi-monthly basis Minimum return of invasive species Stream C-28: There are some established nonnative during the 2018 growing blackberry on the site (NW corner). Reed canarygrass was season. observed in parts of the creek bed. Overall, the invasive cover here is estimated at 5%.

Yarrow Creek: Invasive cover at this planting area is minimal, estimated at 1-2%.

Report Introduction

This report summarizes final-year (Year-5) monitoring activities at the 405 Bellevue to Lynnwood Mitigation Sites. Included are a site description, performance standards, an explanation of monitoring methods, and an evaluation of site success. Monitoring activities included vegetation surveys and photo-documentation on July 9-11, 2018.

3 Estimated values are presented with their corresponding statistical confidence interval. For example, 97% cover (CI80% = 95-100% cover) means we are 80% confident that the true survival rate is between 95% and 100%.

405 Bellevue to Lynnwood Mitigation Sites 1 2018 Annual Monitoring Report What are the SR 405 Yarrow Creek Farm, C28, and Sammamish River Mitigation Sites?

These 0.65-acre, 0.42-acre, and 0.10-acre mitigation sites (Figures 1, 2, and 3) are stream buffer enhancement areas in the I (Interstate) 405 corridor at Yarrow Creek, Stream C28, and the Sammamish River within Water Resource Inventory Area 8. These sites were created to compensate for the impact to 0.73 acre of stream buffer impacts due to road construction and widening along I-405 between Northeast 6th Street in Bellevue and I-5 in Lynnwood. The three stream buffer areas are designed to provide mitigation for lost stream buffer functions including fish and wildlife habitat and biological support.

Figure 1 Sammamish River Site Sketch

405 Bellevue to Lynnwood Mitigation Sites 2 2018 Annual Monitoring Report

Figure 2 Stream C28 Site Sketch

405 Bellevue to Lynnwood Mitigation Sites 3 2018 Annual Monitoring Report

Figure 3 Yarrow Creek Site Sketch

The SR 405 Yarrow Creek, Stream C28, and Sammamish River Mitigation Sites contain forested riparian areas alongside their respective waterways. Appendix 2 includes site directions.

405 Bellevue to Lynnwood Mitigation Sites 4 2018 Annual Monitoring Report What are the performance standards for this site?

Year 5 (Final Year)

Performance Standard 1 Planted tree and shrub species in the buffer enhancement areas of the mitigation sites will achieve at least 80% survival for each of 2 years after the sites are planted.

Performance Standard 2 Monitoring shows minimal return of invasive species. Additional mowing and/or use of approved herbicides to control invasive species.

405 Bellevue to Lynnwood Mitigation Sites 5 2018 Annual Monitoring Report How were the performance standards evaluated?

The tables below document the sample methods used for the Performance Standards (PS) 1 and 2 as required by the mitigation plan. For additional details on the methods see the WSDOT Wetland Mitigation Site Monitoring Methods Paper (WSDOT 2008).

PS 1 PS 2 Attribute Survival Cover Target population Woody plantings Noxious/invasive Zone Entire site Entire site Sample method UBT Qualitative SU length n/a n/a SU width 1 n/a Points per SU n/a n/a 9 (Yarrow Creek) Figure 4 Sammamish River Site Sampling Design 12 (Stream C28) (2018) Total # of SU 13 (Sammamish River) n/a Placement of Baseline: Parallel to river bank Baseline: Length 158 m

405 Bellevue to Lynnwood Mitigation Sites 6 2018 Annual Monitoring Report

Figure 6 Yarrow Creek Farms Sample Design (2018)

Figure 5 C28 Site Sampling Design (2018) Placement of Baseline: The baseline was places along the western boundary of the site. Placement of Baseline: The baselines were placed roughly Baseline: Length 36m along their respective southern and northern fence lines. Segmented Baseline: Length 38m Transects 1-6 Length 47m Transects 7-12

405 Bellevue to Lynnwood Mitigation Sites 7 2018 Annual Monitoring Report Are these sites a success?

These three sites are successfully mitigating for stream impacts that occurred during the Bellevue to Lynnwood Improvement Project. High survival rates of plantings has established native riparian zones. Native woody cover estimates across the sites range from 50-80 percent. Stream C-28 plantings have developed in the understory of an existing forest adding structural complexity to the site. Sammamish River plantings have established on a steep embankment that enhances erosion control and will supply a native seed bank in a reach with significant non-native species. Yarrow Creek Farm vegetation provides an enhanced riparian buffer in a creek with resident cutthroat trout (Oncorhynchus clarkii), coho salmon (Oncorhynchus kisutch) and other anadromous fish. Invasive cover is minimal on all sites at the moment.

405 Bellevue to Lynnwood Mitigation Sites 8 2018 Annual Monitoring Report Results for Performance Standard 1 (At least 80% survival of planted tree and shrub species):

The survival rates for the three sites meet all performance criterion for woody planted species. Details for each site are found below.

Sammamish River: Native woody plantings are estimated at 97 percent survival (CI80% = 95-100%). Native cover is estimated at 50 percent with abundant native Rosa species (roses), Salix species (willows), and snowberry (Symphoricarpos albus) (Photo 1).

Stream C-28: Native woody plantings are estimated at 99 percent survival (CI80% = 98-100%) (Photo 2). Native Photo 1 cover of plantings is estimated at 50 percent, dominated by Sammamish River Buffer Plantings (July 2018) snowberry, salmonberry (Rubus spectabilis), Indian plum (Oemleria cerasiformis), and vine maple (Acer circinatum). The site also has an estimated 95 percent upper canopy cover of native tree species.

Yarrow Creek Farm: Native woody survival is estimated at 100 percent (CI80% = 99-100%). Native cover is estimated at 90 percent with salal (Gaultheria shallon), thimbleberry (Rubus parviflorus), and snowberry (Symphoricarpos albus) being the dominant species (Photo 3).

Photo 2 Stream C28 Buffer Plantings (July 2018)

405 Bellevue to Lynnwood Mitigation Sites 9 2018 Annual Monitoring Report

Results for Performance Standard 2 (Minimal return of invasive species):

Return of invasive species at all three sites is minimal. Estimates for non-native cover do not exceed five percent. Details for each site are found below.

Sammamish River: This planting area is surrounded by Japanese knotweed (Reynoutria japonica) and cutleaf blackberry (Rubus laciniatus). They are encroaching from the edge of the site, particularly the eastern edge. However, cover of invasive species within the planting area is estimated at 3-5 percent.

Stream C-28: There are some established cutleaf blackberry Photo 3 in the northwest corner of the site. Reed canarygrass Yarrow Creek Farms Buffer plantings (July 2018) (Phalaris arundinacea) was observed in parts of the creek bed. Overall, the invasive cover here is estimated at 5 percent.

Yarrow Creek: Invasive cover at this planting area is minimal, estimated at 1-2 percent.

405 Bellevue to Lynnwood Mitigation Sites 10 2018 Annual Monitoring Report What is planned for this site? WSDOT will hold all three sites in a permanent conservation status, preventing the sites from future development. Future maintenance activities may include repairing fences bordering the property, clearing culverts, removing trash, and clearing non- native vegetation and noxious weeds.

405 Bellevue to Lynnwood Mitigation Sites 11 2018 Annual Monitoring Report Appendix 1 – Planting Plans with Photo Point Locations (From WSDOT 2013)

SR 405 Yarrow Creek Mitigation Site

405 Bellevue to Lynnwood Mitigation Sites 12 2018 Annual Monitoring Report SR 405 C28 Mitigation Site

405 Bellevue to Lynnwood Mitigation Sites 13 2018 Annual Monitoring Report SR 405 Yarrow Creek Mitigation Site

405 Bellevue to Lynnwood Mitigation Sites 14 2018 Annual Monitoring Report Appendix 2 – Photo Points The photographs below were taken from permanent photo-points on July 9, 2018 and document current site development.

Yarrow Creek Photo Point 1a Yarrow Creek Photo Point 1b

Stream C-28 Photo Point 1 Stream C-28 Photo Point 2

405 Bellevue to Lynnwood Mitigation Sites 15 2018 Annual Monitoring Report

Sammamish River Photo Point 1 Sammamish River Photo Point 2

Driving Directions:

Yarrow Creek Mitigation Site: From I-5, merge onto I-405 South. Take Exit 17 toward Northeast 70th Place. Turn right onto Northeast 72nd Place and continue onto Northeast 70th Place. Turn right on 116th Avenue Northeast and continue 1.6 miles to the intersection of 116th Avenue Northeast and Northeast 39th Street. The site will be on the right (west) side of 116th Avenue Northeast at this intersection.

Stream C28 Mitigation Site: From I-5, merge onto I-405 South. The site is on the west side of the interstate at milepost 21.3.

Sammamish River Mitigation Site: From I-5, take Exit 154 to merge onto I-405 North. Take Exit 22 for Northeast 160th Street. Turn right on Northeast 160th Street/Juanita Woodinville Way Northeast. Turn left on Northeast Woodinville Drive and follow it under the I-405 overpass. The site will be on the right (north) side of Northeast Woodinville Drive along the Sammamish River, beneath the I-405 overpass.

405 Bellevue to Lynnwood Mitigation Sites 16 2018 Annual Monitoring Report Literature Cited

1. [USACE] US Army Corps of Engineers. 2011. Department of the Army Nationwide Permit Number (14) NWS-2007-1711.

2. 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

3. [WSDOT] Washington State Department of Transportation. 2013. I-405 NE 6th St to I-5 Widening and Express Toll Lanes. Award Copy Planting Plan.

4. [WSDOT] Washington State Department of Transportation. 2013. Stream Mitigation Report I-405, Bellevue to Lynnwood Improvement Project. Seattle (WA): Washington State Department of Transportation, Northwest Region.

405 Bellevue to Lynnwood Mitigation Sites 17 2018 Annual Monitoring Report