DESCRIPTION
The Iverson Marsh Restoration Feasibility Analysis and Conceptual Design will build upon the three previous assessments of the Iverson Marsh (Phillip Williams and Associates , 2001 and Sheldon & Associates, 2001 and Island County DNR, 2017)) to further address the feasibility of restoring inter-tidal marsh at Iverson Marsh. This next phase will seek to incorporate climate resiliency considerations and adaptations for the neighboring community. The project area is approximately 120 acres and consists of 3,200 linear feet of shoreline with one hundred acres currently diked, drained and farmed for hay.
Island County initiated the Iverson Stakeholder Integration Project with the main goal of working with community members to evaluate the possibilities of developing a multi-benefit project that balances the needs of community with a habitat gain for listed species at Iverson Preserve.
The Project had two concurrent phases, one was the data collection and synthesis of sedimentation and groundwater interactions for the Iverson Preserve and the second was the stakeholder integration phase intended to define the most successful community-approved alternative of conceptual design. The data collection and synthesis characterization was to assist with the assessments of current drainage issues and determine acceptable alternatives for restoration at this site. Island County Public Works will make the final decision on any upcoming drainage improvements at Iverson Preserve. The community-led conversation attempted to come up with creative recommendations that could be incorporated into a multi-benefit project.
The Iverson Task Force is a self-selected group of 27 members comprised of park patrons, Long Beach residents, Island County staff, Audubon/birding interest, Friends of Camano Island Parks, and the Mosquito Board. The group was formed to assess community values, vet concerns, and discuss creative, potential, multi-benefit solutions that could be possible at Iverson Preserve. The group came together for 12 meetings to gather relevant information for discussions on potential solutions for drainage and habitat improvements.
The Task Force had two brainstorming sessions to discuss general thoughts and possible solutions for drainage and habitat improvements at the Preserve. A map of the Iverson Preserve was used to write down ideas and sketch out potential solutions. Jim Johannessen with Coastal Geologic Services provided feedback on some of these ideas from an engineering perspective.
Overall impressions:
Assumptions about the drainage from the marsh becoming slower and less effective have been confirmed by the CGS data.
The spit has extended so the outfall must travel further to drain into Port Susan. CGS has found that there is significant increase in sedimentation since 1954.
The existing channel may break through the south end of the spit (known as a "channel avulsion"), which these types of systems have been known to do, and exit into a deeper part of Port Susan closer to the homes on the spit. This would effectively shorten the channel and may improve drainage efficiency. It would also, however, alter the existing tidal circulation and existing habitat in the marsh.
The difference in the sand texture is drastic. It used to be that you didn't sink when you walked out to the spit; now you sink in mud very quickly
The tidal channel and ditches needs the flow behind the tide gate to allow flushing.
Tide gates:
A new tide gate through the Iverson Preserve to Port Susan from parking lot (west to east) may be a good drainage solution. This would shorten the distance the field water has to travel and will be discharged to deeper water.
Create new outfalls across County easements below the spit and pump the field water to the area in front of the houses.
Use the old tide gate (~pre 1980s) on south tip (probably hadn't worked since 1950s) to drain out water to the south.
Remove material from the front of the beach and put it back into the marsh.
Ditches, beavers and mosquitos:
The purpose of the ditch was to get the water out when flooded. Since it is no longer working, it could be filled to remove the mosquito problem.
Jay Lawrence shared droned photography of the Iverson marsh flooded fields and beaver dam from Friday, May 18th, 2017.
The beaver dam causes more flooding in the fields causing more mosquitos. Usually, in an ecosystem, you would have fish feeding on mosquito larvae. The fish are being blocked from entering the marsh area. Engineering the area to be a more natural habitat wou