I-90 Snoqualmie Pass East Project, Phase 1 (Keechelus Lake Wetland) Mitigation Site

USACE IP NWS-2007-2080

South Central Region

2018 MONITORING REPORT

Wetlands Program

Issued March 2019

Environmental Services Office

Author: Tom Mohagen

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: Kristen.Andrews@wsdot.wa.gov

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

I-90 Snoqualmie Pass East Project, Phase 1 (Keechelus Lake Wetland) Mitigation Site

USACE IP NWS-2007-2080

1 Impact numbers sourced from I-90 Snoqualmie Pass East Final Wetlands and Aquatic Resources Mitigation Plan, January 2011, Exhibit ES-2. 2 Mitigation numbers for this site and additional mitigation sites associated with this project are sourced from I-90 Snoqualmie Pass East Final Wetlands and Aquatic Resources Mitigation Plan, January 2011, Table 3-3.

General Site Information

USACE IP Number NWS-2007-2080

Ecology WQC Order # 6299

Mitigation Location Adjacent I-90 on the Keechelus Lake shoreline, Kittitas County

LLID Number 1213777473746

Construction Date 2013

Monitoring Period 2016–2025

Year of Monitoring 3 of 10

Type of Impact Permanent Wetland Temporary Wetland

Area of Project

Impact1 13.07 acres 7.52 acres

Type of Mitigation Wetland Establishment

Planned Area of

Mitigation2 15.0 acres

This Page Intentionally Left Blank

090 Keechelus Lake Wetland 1 2018 Annual Monitoring Report

Summary of Monitoring Results and Management Activities (2018)

Performance Standards 2018 Results3 Management Activities

Density of native facultative or wetter plants will be 4 plants/100ft2

in the wetland creation areas 27.8 plants/100ft² (CI80% = 21.6-33.9) Invasive and non-native treatment From June to August 2018. Treatments switched to manual control from mid Aug through Sept. and one final fall herbicide treatment occurred in the beginning of October.

Less than 20% cover non-native invasive species in the wetland creation areas Less than 1%

Report Introduction This report summarizes third-year (Year-3) monitoring activities at the 090 Keechelus Lake 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 27 and 28, 2018.

3 Estimated values are presented with their corresponding statistical confidence interval. For example, 27.8 plants/100ft2 (CI80% = 21.6-33.9%) means we are 80% confident that the true density value is between 21.6 and 33.9.

090 Keechelus Lake Wetland 2 2018 Annual Monitoring Report

What is the 090 Keechelus Lake Wetland Mitigation Site? This 15.0-acre mitigation site (Figure 1) is a new wetland created on the shore of Keechelus Lake. This site was created to compensate for the permanent loss of 13.07 acres of wetlands and temporary impact to 7.52 acres of wetlands from the Interstate 90 Snoqualmie Pass East road improvement project. The wetland establishment area is designed to improve habitat function for terrestrial species during low pool and aquatic habitat complexity during high pool.

Figure 1 Site Sketch The I-90 Keechelus Lake Wetland Mitigation Site contains an emergent/scrub-shrub wetland on the Keechelus Lake shore. Appendix 2 includes site directions.

090 Keechelus Lake Wetland 3 2018 Annual Monitoring Report

What are the performance standards for this site? Year 3 Performance Standard 1 Native facultative or wetter vegetation will achieve a minimum density of four plants per 100 square feet in the wetland creation areas. Include native facultative or wetter colonizing vegetation in these density calculations. Performance Standard 2 Non-native invasive species (Exhibit 5-2 [Appendix 3, Table 3 in this report]) will be controlled throughout all years, allowing native planted and naturally-recruited, desirable plants to establish and survive. There will be no more than 20 percent cover by non-native invasive species throughout the wetland creation area. Appendix 1 shows the As-Built (WSDOT 2010).

090 Keechelus Lake Wetland 4 2018 Annual Monitoring Report

How were the performance standards evaluated? The tables below document the sampling methodology used for all of the 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 (2016)

Placement of Baseline: Through the center of the site, parallel to I-90. Length 419m Transects 1-27

PS 1 PS 2 Attribute Density Cover

Target population

Native Facultative or Wetter

Invasive Species

Zone Wetland Establishment

Wetland Establishment

Sample method UBT Qualitative SU width 1 m

Total # of SU 26

Baseline

Transect

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How is the site developing? The site is developing on two different time scales. A majority of the native vegetation is concentrated within 60 meters of the toe of the slope of I-90 and along the created channel (Photo 2). This area is developing much quicker than the majority of the site that is sparsely vegetated (Photo 1) almost exclusively by lakeshore sedge (Carex lenticularis). The area near the toe of the slope is the first exposed by the drawdown of Lake Keechelus as a result it has a much longer growing season. Meeting and exceeding the density standard is not a problem but meeting the final year native cover performance may prove more difficult if all the vegetation is concentrated in a small area of such a large site. Results for Performance Standard 1 (Density of four native facultative or wetter plants/100ft2 in the wetland creation areas): Density of native plants is estimated at 27.8 plants/100ft² (CI80% = 21.6-33.9). Lakeshore sedge and field horsetail (Equisetum arvense) make up 83 percent of the species counted. Results for Performance Standard 2 (Less than 20% invasive species in the wetland creation areas): The estimated cover of invasive species is less than one percent. Only one small patch of reed canarygrass (Phalaris

arundinacea) was observed on site.

Photo 1 Native density across a majority of the site (August 2018)

Photo 2 Native density near the I-90 (August 2018)

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What is planned for this site? The region has plans to continue weed control in 2019.

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Appendix 1 – As-Built with Photo Point Locations (from WSDOT 2010)

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Appendix 2 – Photo Points The photographs below were taken from permanent photo-points on August 28, 2018 and document current site development.

Photo Point 1a

Photo Point 1c

Photo Point 1b

Photo Point 2

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Photo Point 3a

Photo Point 3c

Photo Point 3b

Photo Point 4a

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Photo Point 4b

Driving Directions:

From I-90, take Exit 54 toward Hyak/Gold Creek. Turn right onto WA-906. Turn left to stay on WA-906. Turn right onto National Forest Development Road 906.

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Appendix 3 – Data Tables Table 3. Non-native invasive species (Exhibit 5-2 in WSDOT 2011)

Scientific Name Common Name Acroptilon repens Russian knapweed Artemisia absinthium Absinth wormwood Centaurea diffusa Diffuse knapweed Centaurea pratensis Meadow knapweed Centaurea stoebe Spotted knapweed Chondrilla juncea Rush skeletonweed Cirsium arvense Canada thistle Cirsium vulgare Bull thistle Clematis vitalba Field bindweed Cytisus scoparius Scot’s broom Geranium robertianum Herb Robert Hedera helix English Ivy Hieracium aurantiacum Orange hawkweed Hieracium species Yellow hawkweeds Hypericum perforatum Common St. John’s wort Ilex aquifolium English Holly Iris pseudacorus Yellow flag iris Leucanthemum vulgare Ox-eye daisy Linaria dalmatica Dalmatian toadflax Lythrum salicaria Purple loosestrife Polygonum bohemicum, P. cuspidatum, P. sachalinense Knotweeds (Bohemian, Japanese, and giant) Potentilla recta Sulfur cinquefoil Rubus armeniacus (discolor) Himalayan or Armenian blackberry Rubus laciniatus Evergreen blackberry Solanum dulcamara Bitter nightshade Tanacetum vulgare Common tansy

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Literature Cited

1. [USACE] US Army Corps of Engineers. 2009. Department of the Army Individual Permit Number NWS-2007-2080.

2. [USACE] US Army Corps of Engineers. 2013. Department of the Army Individual Permit Modification 2 Number NWS-2007-2080.

3. [USACE] US Army Corps of Engineers. 2015. Department of the Army Individual Permit Modification 3 Number NWS-2007-2080.

4. [WSDOT] Washington State Department of Transportation. 2011. I-90 Snoqualmie Pass East, Final Wetlands and Aquatic Resources Mitigation Plan. Seattle (WA): Washington State Department of Transportation, South Central Region.

5. [WSDOT] Washington State Department of Transportation. 2015. I-90 Snoqualmie Pass East, Final Wetlands and Aquatic Resources Mitigation Plan Addendum. Seattle (WA): Washington State Department of Transportation, South Central Region.

6. [WSDOT] Washington State Department of Transportation. 2010. I-90 Snoqualmie Pass East Project, Keechelus Lake Wetland Mitigation Site As-built Planting Plan.

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