SR 502 NE 15th Ave to NE 102nd Ave

(Sunset Oaks) Mitigation Site

USACE IP NWS-2009-1093

Southwest Region

2018 MONITORING REPORT

Wetlands Program

Issued March 2019

Environmental Services Office

Author: Naomi Korchonnoff

Editor:

Kristen Andrews

Contributors: 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: Kristen.Andrews@wsdot.wa.gov

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

502 NE 15th Ave to NE 102nd Ave (Sunset Oaks) Mitigation Site

USACE IP NWS-2009-1093

1 The area of project impact was referenced from the Final Critical Areas Mitigation Plan SR 502 Corridor Widening (WSDOT 2012). The acreage listed is for the entire SR 502 Corridor project. 2 The planned area of mitigation was referenced from the Final Critical Areas Mitigation Plan – Addendum SR 502 Corridor Widening (WSDOT 2016). A total of 6.54 credit acres have debited from this mitigation site, with 14.39 remaining. There are several additional sites providing mitigation for this project.

General Site Information

USACE IP Number NWS-2009-1093

Ecology WQC Order #8905

Mitigation Location West of the intersection of NE 95th Street and NE 87th Court, Clark County

LLID Number 1225850456931

Construction Date 2012-2013

Monitoring Period 2014-2023

Year of Monitoring 5 of 10

Area of Project

Impact1 11.12 acres

Type of Mitigation Wetland Rehabilitation

Planned Area of

Mitigation2 20.93 acres

This Page Intentionally Left Blank

502 Sunset Oaks 1 2018 Annual Monitoring Report

Summary of Monitoring Results and Management Activities (2018)

Performance Standards 2018 Results3 Management Activities

Wetland Delineation 26.59 acres of wetland, See Appendix 4

Wetland Hydrology Present

Minimum 35% cover of native woody vegetation in wetland rehabilitation and wetland buffer areas.

Buffer:

85% cover (CI95% = 71-98%) PSS/PFO:

71% cover (CI80% = 64-79%)

At least five species of native trees and/or shrubs will be present in the native woody species areas (wetland rehabilitation and wetland buffer areas).

Buffer:

23 species recorded in sample. PSS/PFO:

15 species recorded in sample.

Maximum 15% cover of non-native blackberries and Class B Noxious Weeds on-site.

Buffer:

3% cover (CI80% = 1-5%) PSS/PFO:

1% cover (CI95% = 0-3%)

2018: Three weed control visits. 2017: Two weed control visits.

Class A Noxious weeds, Japanese knotweed, and purple loosestrife shall be treated so that the species do not exist on the site. None observed.

Maximum 25% cover of reed canarygrass on-site.

Buffer:

1% cover (CI90% = 0-2%) PSS/PFO:

45% cover (CI80% = 36-54%)

3 Estimated values are presented with their corresponding statistical confidence interval. For example, 85% cover (CI80% = 71-98% cover) means we are 85% confident that the true cover value is between 71% and 98%.

502 Sunset Oaks 2 2018 Annual Monitoring Report

Report Introduction This report summarizes fifth-year (Year-5) monitoring activities at the 502 Sunset Oaks Mitigation Site. Included are a site description, the performance standards, an explanation of monitoring methods, and an evaluation of site development. Monitoring activities in 2018 included vegetation surveys, photo-documentation, assessments of wetland hydrology, and a wetland delineation. Vegetation monitoring was conducted on July 30, July 31, and August 1. Hydrology monitoring occurred on March 8, March 22, and April 16. The wetland delineation was conducted between March 25 and March 27, 2018.

502 Sunset Oaks 3 2018 Annual Monitoring Report

What is the 502 Sunset Oaks Mitigation Site? This 33-acre mitigation site (Figure 1) is rehabilitated wetland located east of I-205 within the urban growth area of Vancouver in Clark County. This site was established in part to compensate for the loss of 11.12 acres of wetlands due to road improvements along State Route (SR) 502. The realigned channel, associated backwater habitat, and scrub-shrub wetlands are designed to provide mitigation for lost functions including flood-flow alteration, nutrient and sediment removal, and wildlife habitat.

Figure 1 Site Sketch The 502 Sunset Oaks Mitigation Site contains a mosaic of forested, scrub shrub, and emergent systems on either side of the realigned Curtin Creek. Upland and wet buffer areas surround the site to the east, west, and south.

502 Sunset Oaks 4 2018 Annual Monitoring Report

What are the performance standards for this site? Year 5 Performance Standard 1 Wetlands at the mitigation site will be delineated at monitoring Year 5 to assess the development of estimated wetland conditions and the development of Cowardin vegetation classes. Performance Standard 2 The soils will be saturated to the surface, or standing water will be present 12 inches or less below the surface for at least 10 percent of the growing season (growing season as defined in the Soil Survey of Clark County, WA., USDA, 1972) in years when rainfall meets or exceeds the 30-year precipitation average. Performance Standard 3 At monitoring Year 5 and 7, minimum cover of native woody vegetation (planted trees, volunteer trees, and shrubs) in wetland rehabilitation and wetland buffer areas as follows: minimum 35 percent cover of native woody vegetation (planted and volunteer). Performance Standard 4 At least five species of native trees and/or shrubs will be present in the native woody species areas (wetland rehabilitation and wetland buffer areas). Performance Standard 5 The aerial extent of Blackberry Species and Class B (WA Dept of Agriculture and Clark County Weed Board) noxious weeds will not exceed 15 percent in the combined wetland rehabilitation and buffer areas. Performance Standard 6 If/when detected, Class A Noxious Weeds (WA Dept. of Agriculture and Clark County), Japanese Knotweed, and Purple Loosestrife shall be treated so that the species do not exist on the site. These species shall not be included in the 15 percent cover allowed for invasive species. Performance Standard 7 At monitoring Years 1, 3, 5, and 7, the aerial extent of Reed Canarygrass shall not exceed 25 percent total cover in the wetland rehabilitation or buffer enhancement areas.

502 Sunset Oaks 5 2018 Annual Monitoring Report

Year 10 Performance Standard 8 At monitoring Year 10, minimum cover of native vegetation (planted and volunteer) in (planted trees, volunteer trees, and, shrubs) in wetland rehabilitation and wetland buffer areas as follows: minimum 70 percent cover of native woody vegetation (planted and volunteer trees and shrubs). Appendix 1 shows the as-constructed planting plan (WSDOT 2014).

502 Sunset Oaks 6 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: Western Mountains, Valleys, and Coast Region (Version 2.0) (USACE 2010) and a Global Positioning System (Trimble Mapping Grade) (Performance Standards 1 and 2). Shallow groundwater monitoring wells were installed following the Corps of Engineers guidance (USACE 2005) to evaluate groundwater during the growing season. The tables below document the sample method used for all of the remaining performance standards (PS) as required by the mitigation plan and permits. 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 PSS/PFO Sample Units: Starting points for sample units were generated in a GIS using a simple random method. Placement of Buffer Baseline: An 886-meter-long baseline was placed in two segments on either side of Curtin Creek. Twenty-two sampling transects were positioned 40 meters apart along the baseline segments.

PS 3,4,8 PS 3,4 PS 5&7 PS 5&7 PS 6

Attribute Cover Cover Cover Cover Presence/Absence

Target population

Native woody species

Native woody species

Noxious weeds

Noxious weeds

Noxious weeds

Zone Buffer PSS/PFO Buffer PSS/PFO Entire site Sample method

Line Intercept

Line Intercept

Point Line Point Line Qualitative

SU length 10 10 10 10 N/A Points/SU N/A N/A 20 20 N/A

# of SU 20 24 20 24 N/A

502 Sunset Oaks 7 2018 Annual Monitoring Report

How is the site developing? In general the site is developing well and is exceeding Year-5 woody cover performance standards. Cover of reed canarygrass (Phalaris arundinacea), however, is likely exceeding the 25 percent performance standard threshold across the site and is inhibiting development of native woody cover in some areas. Apart from reed canarygrass, the cover of noxious weeds is low across the site. While hydrology monitoring did not show consistent wetland hydrology in all areas of the intended wetland, much of the site did have long-duration surface water in the spring of 2018. A variety of wildlife has been observed using the site including Pacific chorus frogs, bullfrogs, garter snakes, and evidence of deer, possums, raccoons, and muskrats (denning on site). Fish observed on site include smallmouth bass, pumpkinseed, and bluegills. A wide range of bird species have been observed as well, including many wetland-dependent species such as Great Blue Heron, Belted Kingfisher, Canada Goose, Mallard, Red-winged Blackbird, Wilson's Snipe, and Greater Yellowlegs.

502 Sunset Oaks 8 2018 Annual Monitoring Report

Results for Performance Standard 1 (Wetland Delineation): The site was delineated on March 26, 2018. A total of 26.59 acres of wetland were delineated on-site. Cowardin vegetation classes are generally developing as intended. See Appendix 4 for full delineation results. Results for Performance Standard 2 (The soils will be saturated to the surface for at least 10 % of the growing season): Shallow groundwater wells one through three exhibited water in the upper twelve inches of the soil surface for all three site visits that occurred in March and April 2018 (Photo1) Wells four through six were paired with data loggers that measured the water level four times per day. Wells four and five showed water levels well within the top twelve inches of the soil surface. Well six did not. It is located in an area that slopes up from the wetland and receives mostly overland flow when water levels rise in this flashy urban system. See Appendix 3 for results. Conditions were also drier than normal leading up to hydrology monitoring. Results for Performance Standard 3 and 8 (Minimum 35% cover [70% in Year 10] of native woody vegetation): The cover of native woody vegetation is estimated at 85% (CI95% = 71-98%) in the buffer and 71% (CI80% = 64-79%) in the wetland. Although native woody vegetation is thriving in most of the site, cover is patchy in the southeastern wetland

where conditions are drier (Photo3). The buffer woody cover is meeting the final-year (Year 10) performance standard. Results for Performance Standard 4 (At least five species of native trees and/or shrubs will be present): At least 23 native trees and shrub species were found in the buffer, and at least 15 species were found in the wetland. Robust growth of Salix species (willows) and Red Osier Dogwood (Cornus sericea) is observed throughout most of the wetland (Photo2).

Photo 1 Inundation in Wetland (March 2018)

502 Sunset Oaks 9 2018 Annual Monitoring Report

Photo 2 Native woody cover in Wetland (March 2018) Results for Performance Standard 5 (Maximum 15% cover of non-native blackberries and Class B Noxious Weeds on-site): The cover of non-native blackberries and Class B noxious weeds on-site is estimated at 3% cover (CI80% = 1-5%) in the buffer and 1% cover (CI95% = 0-3%) in the PSS/PFO. This cover is primarily of Himalayan blackberry (Rubus

armeniacus), but also includes smaller amounts of Scotch broom (Cytisus scoparius), Robert geranium (Geranium

robertianum), and tansy ragwort (Jacobaea vulgaris).

Results for Performance Standard 6 (Class A Noxious weeds, Japanese knotweed, and purple loosestrife shall be treated so that the species do not exist on the site): None of the applicable species were observed on-site. Results for Performance Standard 7 (Maximum 25% cover of reed canarygrass on-site): The cover of reed canarygrass (Phalaris arundinacea) on-site is estimated at 1% cover (CI90% = 0-2%) in the buffer and 45% cover (CI80% = 36-54%) in the wetland. Although patches of reed canarygrass are scattered throughout the site, it is more prevalent on the northeast side of the site (where it is generally wetter) than on the west side.

Photo 3 Native woody cover in Wetland (August 2018)

502 Sunset Oaks 10 2018 Annual Monitoring Report

What is planned for this site? Intensive reed canarygrass (Phalaris arundinacea) control will occur throughout 2019. These areas will be evaluated in the fall of 2019 for possible replanting.

502 Sunset Oaks 11 2018 Annual Monitoring Report

Appendix 1 – As-Constructed Planting Plan with Photo Point

and Hydrology Well Locations (from WSDOT 2014)

502 Sunset Oaks 12 2018 Annual Monitoring Report

Appendix 2 – Photo Points The photographs below were taken from permanent photo-points on August 3, 2016 and document current site development.

Photo Point 1a

Photo Point 1c

Photo Point 1b

Photo Point 2

502 Sunset Oaks 13 2018 Annual Monitoring Report

Photo Point 3a

Photo Point 3c

Photo Point 3b

Photo Point 3d

502 Sunset Oaks 14 2018 Annual Monitoring Report

Photo Point 3e

502 Sunset Oaks 15 2018 Annual Monitoring Report

Appendix 3 – Hydrology Table 1. Hydrology Observations

Date Surface Observations Well ID #

Water Level (inches below soil surface unless otherwise noted)

March 08, 2018 Around 85 percent of the site is inundated. 1 9" 2 0” 3 5”

March 22, 2018 Soil surface saturated or inundated. Overall, 85 percent of wetland observed to have some hydrology.

1 6" 2 0" 3 1”

April 16, 2018 Channels and backwaters are inundated and the surrounding wetlands are saturated to the surface. Near the buffer the saturation lessens but hydrophytic vegetation persists.

1 9” 2 0.5” 3 4.5”

502 Sunset Oaks 16 2018 Annual Monitoring Report

502 Sunset Oaks 17 2018 Annual Monitoring Report

502 Sunset Oaks 18 2018 Annual Monitoring Report

502 Sunset Oaks 19 2018 Annual Monitoring Report

Table 2. Comparison of Observed and Normal Precipitation (NRCS 2015) Monthly precipitation data for Vancouver, Washington.

Long-term rainfall recordsa

Month 3 yrs. in 10 less

than Average

3 yrs. in 10 more

than Rain falla

Condition dry, wet, normalb

Condition Value

Month weight value

Product of previous two

columns

1st prior month Feb 3.01 4.39 5.24 1.80 D 1 3 3

2nd prior month Jan 3.94 5.79 6.91 9.02 D 1 2 2

3rd prior month Dec 4.65 6.64 7.89 3.77 D 2 1 2

Sum 7 aNRCS 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: Drier than normal precipitation conditions were present leading up to the hydrology field visits.

502 Sunset Oaks 20 2018 Annual Monitoring Report

Table 3. Daily Precipitation 10 days preceding field work, Vancouver, Washington

Prior to March 6 visit Prior to March 22 visit Prior to April 4 visit

Date (2018) Daily Precipitation (inches)a Date (2018) Daily Precipitation

(inches)a Date (2018) Daily Precipitation (inches)a

March 5 0.05 March 21 0.00 April 3 0.01

March 4 0.00 March 20 0.00 April 2 0.00

March 3 0.00 March 19 0.01 April 1 0.00

March 2 2.26 March 18 0.23 March 31 0.00

March 1 0.46 March 17 0.00 March 30 0.00

February 28 0.05 March 16 0.31 March 29 0.00

February 27 0.00 March 15 0.01 March 28 0.03

February 26 0.31 March 14 0.38 March 27 0.06

February 25 0.01 March 13 0.01 March 26 0.03

February 24 0.12 March 12 0.00 March 25 0.13

Total: 3.26 Total: 0.95 Total: 0.26 a NRCS 2018 “S” This data value failed one of NCDC’s quality control tests. “T” values indicate a TRACE value was recorded. “M” values indicate missing data.

“A” values indicate a multiday total, accumulated since the last measurement.

502 Sunset Oaks 21 2018 Annual Monitoring Report

Appendix 4 – Delineation Report

502 Sunset Oaks 22 2018 Annual Monitoring Report

Literature Cited

1. Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Vicksburg (MS): US Army Engineer Waterways Experiment Station. Technical Report Y-87-1. Available at: http://www.swl.usace.army.mil/Portals/50/docs/regulatory/wlman87.pdf

2. [NOAA] National Oceanic and Atmospheric Administration (US) [Internet]. 2018. NOAA Online Weather Data. National Weather Service Forecast Office. Available at: http://www.nws.noaa.gov/climate/xmacis.php?wfo=sew

3. [NRCS] Natural Resources Conservation Service [Internet]. 2018. Field Office Technical Guide - Climate Data. US Department of Agriculture. Available at: https://efotg.sc.egov.usda.gov/

4. [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

5. [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

6. [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: http://www.usace.army.mil/Portals/2/docs/civilworks/regulatory/reg_supp/west_mt_finalsupp.pdf

7. [USACE] US Army Corps of Engineers. 2012. Department of the Army Individual Permit Number NWS-2009-1093.

8. [WSDOE] Washington State Department of Ecology. 2012. Water Quality Certification Order #8905.

9. [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

502 Sunset Oaks 23 2018 Annual Monitoring Report

10. [WSDOT] Washington State Department of Transportation. 2012. Final Critical Areas Mitigation Plan SR 502 Corridor

Widening. Vancouver (WA): Washington State Department of Transportation, Southwest Region.

11. [WSDOT] Washington State Department of Transportation. 2014. SR-502 Corridor, Phases 1 and 2 Wetland Mitigation Site As-Built Documentation (Draft) Corps #NWS-2009-1093 [Memorandum]. Vancouver (WA): Washington State Department of Transportation, Southwest Region.