Marsh Restoration and Estuary Expansion - Unocal Proposal

6/30/24

Summary

The Edmonds Marsh Estuary Advocates recommend restoring the land adjacent to the existing Edmonds Marsh so that it is once again saltwater estuary habitat. The restoration proposal is to create a direct connection between the marsh and Puget Sound and to expand the existing wetland and estuary environment.

 Because of the regional importance of this increasingly rare ecosystem in Puget Sound, the plan would be attractive to funding sources that support land purchase and restoration. Along with ecological and funding advantages, the proposal benefits include increased flood water storage capacity, reduced risks due to contaminated soils, carbon mitigation, and improved recreational opportunities for Edmonds citizens and visitors.

Existing Conditions

This restoration proposal includes four land parcels: Marina Beach Park, the Unocal site, the Willow Creek hatchery parcel, and the Edmonds Marsh. The figure below shows these parcels and the current location and condition of the Unocal site, which once operated as a bulk fuel oil terminal.

 Much of the Unocal site currently consists of fill that covers a historic saltwater estuary. The site is currently undergoing an environmental cleanup effort by the responsible party (Chevron) under the direction of the Washington State Department of Ecology. The main cleanup method used has been the removal of contaminated soils and replacement with clean fill, seen as light colored areas in the figure below. The cleanup effort has been ongoing for 23 years and is now reaching its conclusion.

 Fresh water flows into the marsh from various sources including Willow Creek, Shellabarger Creek, and various stormwater drainage systems. This freshwater inflow is currently now collected into a ditch that parallels the BNSF railroad tracks, shown in blue below. Water passes through culverts under those tracks and then enters a 1,600 foot long pipeline which extends into Puget Sound. This pipe is impassible to salmon and reduces the influence of saltwater in the marsh.

 The Expanded Estuary Concept

The diagram below shows the basic elements of the proposed expanded estuary concept. The long marsh pipeline would no longer be used. Instead, the flow would move through open water marsh, estuary, and channels toward the southwest corner of the site. It would then pass under the existing railroad bridges, and then to a connector channel that delivers it to Puget Sound. This reconnection would allow passage of fresh water, salt water, and aquatic organisms into and out of the marsh.

 Estuary expansion and reconnection would occur by excavating fill from the Unocal site. Some areas of remaining contamination may remain after final cleanup and would be managed with an environmental covenant. Limiting excavation in those areas reduces potential contact with contaminated soil. The largest of these is shown below as the “SR104 stormdrain contamination area”.

 Proposal Options:

Floodwater protection for the developed portion of the waterfront.
This protection could be in the form of small earthen berms on the north side of the marsh and/or a high tide gate near the connection of the marsh estuary to the Sound just upstream of the railroad bridges.  
A walkway around all or part of the marsh estuary.
This walkway could be part of the floodwater protection berm. Observation platforms on the south border would add recreational and educational value.
Adding SR104 watershed flow from the stormwater pipeline into the marsh estuary.
A large stormwater line passes under the site and out into Puget Sound. Intercepting this pipeline near its entrance to the marsh estuary and directing that flow into the system would add freshwater influence. Treating that stormwater before it enters the marsh estuary would be a beneficial process.
An interpretive center.
The existing Willow Creek hatchery building could be rebuilt to include an interpretive/learning center.

Proposal Benefits:

This restoration alternative provides the unique opportunity to reclaim some of the historic tidal wetland area that was lost to development. Benefits include: ­­­­­­
Puget Sound Health
Most tidal saltwater estuary habitat has disappeared in Puget Sound, by some estimates 75% is gone. Nutrient rich and penetrated by sunlight, this habitat is some of the most biologically productive on earth. Estuaries provide a nourishing foundation that supports the wide range of life in Puget Sound.
Salmon Recovery
Multiple agencies have confirmed the importance of this type of environment for salmon recovery. For example, The Pacific Fishery Management Council has listed estuaries as a salmon HAPC, “Habitat Area of Particular Concern”. Chum and coho salmon would spawn in the creeks that feed the Edmonds marsh estuary and their young would rear in its open waters. Juvenile Chinook salmon would also migrate from the Sound into the estuary to feed. The site would be the only significant estuary habitat between Seattle and Everett and would act an island water sanctuary for migrating salmonids.
Other Fish and Wildlife
Estuaries also provide critical habitat for millions of migratory and resident waterfowl. This tidally influenced open saltwater area would become priority bird habitat. 
Estuaries are nursery ecosystems for multiple aquatic species. Dungeness crab, starry flounder, English sole, and bay shrimp are among the animals using estuaries at various life stages.
Environmental Justice
Puget Sound coastal tribes have a cultural and economic dependency on natural resources and are disproportionately impacted by loss of habitat and sea level rise. Adding estuary capacity to Puget Sound supports tribal treaty rights and the economic health of those communities. 
Funding
Salmon recovery, national estuary, nearshore restoration, wildlife enhancement, outdoor recreation, and other programs are grant funding sources that are available to support estuary restoration.
Recreation and Education
As an important part of a regional park and wildlife sanctuary, the expanded estuary would attract both residents and visitors to Edmonds. The open water estuary habitat would increase the numbers and species of birds to be viewed and adult salmon would migrate through the park. Unique educational opportunities would be created by estuary habitat near an urban center.
Flood Elevations
The removal of fill will significantly increase the flood storage capacity of the marsh estuary system. Also, the addition of berms along the north sides of the marshes would prevent flooding of Dayton Avenue and Harbor Square from overflows from the marsh which will occur more frequently in the future as the climate changes and sea levels rise.
Contaminated Soil Risk
Removal of potentially contaminated Unocal lower yard soils reduces risks to the future property owner. It also reduces the potential for ground and surface water to become contaminated.
Water Quality
Untreated stormwater is considered one of the principal problems for Puget Sound health. Intercepting and treating stormwater from SR104 can help reduce the impact that Edmonds has on Sound water quality.
Estuaries also have more general water quality benefits. They help filter and settle out pollutants and nutrients.
Carbon mitigation
Estuaries capture significantly more carbon than forests, they store it faster, and the carbon stays out of the atmosphere for longer.

 Conclusion
The multiple benefits of expanding estuary habitat at the Edmonds Marsh make it an alternative that should be evaluated as an alternative for Edmonds Marsh restoration.

The City’s public GIS system illustrates five critical area designations of the Marsh and surrounding areas
including the UNOCAL property. You can view them HERE.