One day in advance of the firm’s scheduled presentation to the Edmonds City Council, consultant Windward Environmental shared the results of its recently-completed 18-month baseline monitoring study to an estimated 50 citizens during a Monday evening open house.
The purpose of the study was to evaluate the ecological functions of the marsh and its buffers. The report includes work from local groups including Edmonds-Woodway High School’s Students Saving Salmon and citizen photographers who captured images of the marsh and its wild inhabitants throughout the study period. Scientists from Windward were on hand to narrate a slide presentation, highlight Marsh Study maps, and answer questions.
“This is a great educational opportunity for the community, said City Councilmember Diane Buckshnis, who chaired the council’s Marsh Study Task Force. “We hope that the findings in this report will increase interest in the marsh and foster a deeper commitment to its protection and restoration.”
The report was presented by Windward scientists and principal investigators Jennifer Love and Ron Gouguet, who provided a detailed overview, walking the audience through the various phases of the study and reporting their findings. The sometimes data-heavy presentation included detailed reviews of project tasks completed; goals, materials and methods; summaries of physical and biological monitoring parameters; and an evaluation of the Edmonds Marsh Estuary Restoration Project in light of the data generated by the study. For each of these tasks, the team delved into the underlying sub-tasks, explaining each in detail.
The study began 18 months ago with a year-long baseline monitoring study, during which data and information were collected on parameters that included soil and sediment characteristics, water depth and quality, vegetation, invertebrates and other wildlife, and longitudinal photographic surveys. Particular attention was paid to the various buffer zones along the marsh perimeter, with separate data sets collected from the buffers along the north, south and southeast. Data were also collected from the marsh interior. For each, the team laid out their methodologies and findings.
After a pause for questions and answers, Love and Gouguet moved into summarized reports of findings of the physical and biological monitoring tasks for the marsh interior and various buffer zones. Physical parameters included composition and characteristics of soils, sediments and water quality — pH, temperature, turbidity, dissolved oxygen and salinity. Biological parameters included the presence and diversity of vegetation, insects and other invertebrates, birds and mammals. Among the latter were foraging, breeding and nesting, and predator-prey interactions. Reptiles and amphibians were not formally surveyed.
After another question-and-answer session, the team provided its literature review findings, particularly as those findings relate to buffers. The focus was on parameters including buffer width, flow rates through buffers, and presence or absence of vegetation, shading and woody debris. The findings suggest that buffers narrower than 50 feet are ineffective at protecting wetlands from disturbance, especially when adjacent land use is high, and that widths of 100-164 feet are generally recommended for reducing disturbance, with greater widths (200-328 feet) recommended to prevent disturbing waterfowl including great blue herons.
Windward then applied these criteria to its findings from studying the marsh buffers, noting that despite the current buffers being narrower than generally recommended in the literature, the wildlife that uses the marsh seems well-adapted to surrounding human activities and noise (e.g., BNSF tracks, ferry horns, SR 104 traffic). They did, however, note that the animals are distressed by people entering or traversing the marsh, as was highlighted by their data collection crews during the course of the study.
At the end, the team presented its evaluation of the latest Edmonds Marsh Estuary Restoration Project report from city consultant Shannon & Wilson, which prepared pre-design information on plans to daylight — or open — the waterway. Willow Creek currently flows through the Edmonds Marsh, then enters a 1,600-foot piping system, to Puget Sound. Officials have said that the piping system prevents salmon from being able to return from Puget Sound to Willow Creek to spawn.
Windward’s analysis estimated the difference between current habitat functions and those that would be expected post-restoration according to the Shannon & Wilson report. Windward cautioned that this comparison is based on a computer modeling simulation where the data from the Windward study was analyzed along with projected information extrapolated from the Shannon & Wilson report. The computer model yielded a numerical result of a 62 percent increase in the “level of ecosystem services” post-daylighting.
“It’s not our job to say this (daylighting) is the solution,” concluded Gouguet. “We can say that daylighting would change the environment of the marsh, and the various plants and animal would be affected differently. While we don’t think this is a fully defensible number, I think we can say that things would generally get better post-daylighting.”
The full library of materials from the Windward study are available on the city council website here.
You can see the PDF of the presentation here.
— Story and photos by Larry Vogel