SR 240 I-182 to Columbia Center Interchange (Columbia Causeway) Mitigation Site USACE IP 2004-00043 South Central Region 2018 MONITORING REPORT Wetlands Program Issued March 2019 Environmental Services Office Author: Jennie Husby Editor: Kristen Andrews Contributors: Kristen Andrews Jennie Husby Tom Mohagen Sean Patrick 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 SR 240 I-182 to Columbia Center Interchange (Columbia Causeway) Mitigation Site USACE IP 2004-00043 General Site Information USACE IP Number 2004-00043 Ecology WQC 1760 On both sides of SR 240 at milepost 37 in Mitigation Location Benton County LLID Number 1192477462437 Construction Date 2005–2007 Monitoring Period 2009-2018 Year of Monitoring 10 of 10 Type of Impact Permanent Wetland Area of Project Impact1 9.65 acres Upland Wetland Wetland Type of Mitigation Vegetation Establishment Enhancement Preservation Planned Area of 10.19 acres 5.62 acres 0.7 acre Mitigation2 1 Impact and mitigation numbers sourced from SR 240, I-182 to Columbia Center Interchange Construct Additional Lanes Final Mitigation Plan Addendum (WSDOT 2008). 2 Additional off-site mitigation credit of 3.2 acres obtained from Amon Creek for fish passage enhancement and simulated stream channel construction. This Page Intentionally Left Blank 240 Columbia Causeway 3 2018 Annual Monitoring Report Summary of Monitoring Results and Management Activities (2018) 2018 Results3 Performance Standards Management Activities East Unit West Unit Wetland Delineation (15.79 acres wetland) 15.67 acres (See Appendix 4) 36% cover 41% cover (CI80%= 28-43%) (CI80%= 25-56%) 50% cover native wetland trees and shrubs in the combined PSS and PFO (58% (CI80%= 47- (70% (CI80%= 57- 69%) if Lombardy 83%) if Lombardy poplar included) poplar included) 43% cover (CI80%= 24-62%) 50% cover native wetland herbaceous plant species in the PEM (81% (CI80%= 66- 95%) if narrowleaf cattail included) Five native tree and/or shrub species in the PSS/PFO Achieved Three native herbaceous species in the PEM Achieved 49% cover 40% cover native plant species in the upland buffer (CI80%= 39-59%) Three native plant species in the upland buffer Achieved No Washington State-listed or county-listed Class A weeds None observed Weed control activity Control of Benton County-designated Class B and C weeds None observed occurred twice a month Less than 15% cover kochia (Bassia scoparia), puncturevine (Tribulus 10% cover common reed and Russian olive; from June through terrestris), common reed (Phragmites australis), prickly Russian thistle (Salsola no kochia, puncturevine, or prickly Russian September in 2018 tragus) and Russian olive (Elaeagnus angustifolia) combined across the site thistle observed 3 Estimated values are presented with their corresponding statistical confidence interval. For example, 36% cover (CI80% = 28-43%) means we are 80% confident that the true cover value is between 28% and 43%. 240 Columbia Causeway 1 2018 Annual Monitoring Report Report Introduction This report summarizes final-year (Year 10) monitoring activities at the 240 Columbia Causeway 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 on photo-documentation July 30, August 1, and September 10, 2018, and a wetland delineation on April 12, 2017. 240 Columbia Causeway 2 2018 Annual Monitoring Report What is the 240 Columbia Causeway Mitigation Site? This 15.81-acre mitigation site (Figure 1) contains 10.19 acres of wetland establishment and 5.62 acres of wetland enhancement located on both sides of State Route (SR) 240 just south of the Yakima River. This site was created to compensate for the loss of 9.65 acres of wetlands due to the addition of lanes and a pedestrian/bike path from MP 63.26 and 37.59 and MP 37.84 and 38.71 along the SR 240 corridor between Richland and Kennewick in Benton County, WA. The recently established and enhanced emergent, scrub-shrub and forested wetlands are designed to provide mitigation for lost wetland functions including wildlife habitat, flood flow alteration, and contaminant buffering. Figure 1 Site Sketch The 240 Columbia Causeway Mitigation Site is comprised of two sections, positioned on either side of SR 240. The long portion on the east side of the SR is located adjacent to the confluence of the Yakima River and the Columbia River (East Unit). A conveyance (wildlife tunnel) structure connects this portion of the site with a canal enhancement area on the west side of the SR (West Unit). In addition, a land purchase of 15.59 acres on Amon Creek compensates for an additional 3.2 credits of mitigation. Appendix 2 contains directions to the site. 240 Columbia Causeway 3 2018 Annual Monitoring Report What are the performance standards for this site? Year 10 Performance Standard 1 In the wetland establishment and enhancement areas, soils will be inundated or saturated to the surface, or groundwater will be present within 12 inches of the surface at least 20 consecutive days during the growing season in years when precipitation is equal to or greater than the 30-year average at the weather station nearest to the SR 240 mitigation site. Hydrology will be measured at 10 or more locations at or near the upland/wetland boundary. The wetland boundary will be delineated using methods approved by the US Army Corps of Engineers and the Washington Department of Ecology to determine the area of wetland on site. Current approved methods are described in the Corps of Engineers Wetlands Delineation Manual (Environmental Laboratory 1987) and the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region (USACE 2008). The designated establishment and enhancement areas at the SR 240 mitigation site will contain at least 15.79 acres of wetland. Wetland areas designated as “buffer” for regulatory purposes along the west edge of the East Unit are not included in the minimum required wetland area. Performance Standard 2 Cover of native wetland trees and shrubs (planted and volunteer) will be at least 50 percent in the combined scrub-shrub and forested communities. Performance Standard 3 Cover of native wetland herbaceous plant species (planted and volunteer) will be at least 50 percent in the emergent communities. Performance Standard 4 There will be at least five native tree and/or shrub species present in the scrub-shrub and forested wetlands. Performance Standard 5 There will be at least three native herbaceous species present in the emergent communities. 240 Columbia Causeway 4 2018 Annual Monitoring Report Performance Standard 6 Cover of native plant species (planted and volunteer) will be at least 40 percent in the upland buffer. Performance Standard 7 There will be at least three native species present in the upland buffer. Performance Standard 8 Washington State-listed or county-listed Class A weeds must be eradicated. All occurrences shall be immediately reported to the site manager and an eradication program will be initiated within 30 days of the report. The following Class A weeds are of particular concern to the Benton County Noxious Weed Control Board (BCNWCB 2010): buffalobur nightshade (Solanum rostratum) and flowering rush (Butomus umbellatus). Performance Standard 9 The following Class B and Class C weeds have been designated for control by the Benton County Noxious Weed Control Board (BCNWCB 2010). If any of the following species are found on the site during the monitoring period, occurrences shall be immediately reported to the site manager and control measures will be initiated within 30 days of the report: (See Appendix 3, Table 1). Performance Standard 10 For the following weeds, combined cover will not exceed 15 percent across the mitigation site: burning bush, puncturevine, common reed, prickly Russian thistle, and Russian olive. Appendix 1 shows the planting plan (Davari 2006). 240 Columbia Causeway 5 2018 Annual Monitoring Report How were the performance standards evaluated? WSDOT staff collected hydrology data and performed a wetland delineation using methods described in the Corps of Engineers Wetlands Delineation Manual (Environmental Laboratory 1987), Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Arid West Region (Version 2.0) (USACE 2010) and a Global Positioning System (Trimble Mapping Grade) (Performance Standard 1). Appendix 3, Table 2 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). Placement of Baseline: Parallel to SR 240 through the buffer in the East and West Units East Unit: Length 1,024m, Transects - 19 West Unit: Length 396m, Transects - 14 Figure 2 Site Sampling Design (2018) 240 Columbia Causeway 6 2018 Annual Monitoring Report Is this site a success? This site is considered successful even though percent cover of native trees, shrubs, and herbaceous plants is lower than the performance standard thresholds. This determination is justified by the fact that non-native Lombardy poplar (Populus nigra), a dominant woody species in the wetland and common in the greater landscape of the Yakima River Delta, provides the same wetland functions as native woody tree species. If Lombardy poplar is included in the cover calculation, the percent cover standard would be easily met. This holds true for non-native narrowleaf cattail (Typha angustifolia) as well, as it is very common on the delta and provides the same wetland functions as native Typha latifolia. Cover of native species in the buffer is high. Wildlife habitat has increased throughout the site.