Beginning in July and extending into early September, those who travel Elk City Road upriver from Toledo, will notice equipment in the tidal marsh across the Yaquina River.
The MidCoast Watersheds Council (MCWC) and partners will be working to restore a 55-acre site owned by The Wetlands Conservancy so that juvenile salmon and other important estuary species can thrive here.
“Tidal wetlands are extremely important for salmon, as they act as nursery grounds where fish find food and cover, and grow to larger sizes that give them a better chance of surviving in the ocean and returning to spawn,” said Evan Hayduk, Council Coordinator for MCWC.
While it has been known how important early rearing in estuaries is for juvenile chum salmon, research in the restored Salmon River estuary north of Lincoln City has shown how vital these habitats are for Chinook salmon and threatened coho salmon. That research showed that young coho that had spent extended periods of time in the estuary accounted for 20-35% of the adults returning to spawn a few years later. Similarly, but to an even greater degree, more than 50% of the returning adult Chinook salmon also had spent more time as juveniles in the nutrient rich and protected waters of the estuary.
Beyond the benefit to salmon species this project also focuses on building resilience to sea level rise and flooding, restoring forested tidal wetland habitat, and increasing the uptake and storage of carbon in the soils. Recent research completed in 2019 found that about 67.4% of the Yaquina’s tidal marshes and swamps had been converted to other uses by historic diking, ditching, and draining.
According to Fran Recht, Habitat Program Manager for the Pacific States Marine Fisheries Commission, who is co-managing the project with Hayduk, “when a marsh area is cut off from tidal influence by a dike or tide gate, sediment can’t enter the site. This, and the resultant loss of native vegetation that adds a lot of biomass to the soil, can lead to subsidence that makes the area more vulnerable to flooding.”
The sooner restoration work is implemented, the greater the likelihood that these areas can remain as marshes rather than becoming bare mudflats as sea level rises.
“While mudflats are important habitats in their own right, but for salmon, maintaining the marshes and their channels are key,” Recht said.
This summer’s restoration work will build on and expand the previous efforts that took place at the site in 2001. The earlier project breached the dike in five places, filled linear drainage ditches and restored the sinuous channels that added habitat area. Those dike breaches increased tidal exchange on about 38 acres of the 55-acre site and allowed for fish to access rearing habitat.
Just one month after that project was implemented, a fish survey in a new tidal channels recorded a school of thousands of juvenile Pacific herring foraging during a high, 7.5 foot tide. In other surveys between 2003 and 2006, abundant coho salmon, shiner perch, and stickleback were observed. Additionally, native plants became established and invasive weeds were controlled.
This summer’s project will further increase tidal connectivity to the marsh by removing more than half of the perimeter dike still present on the site, filling additional linear drainage ditches, and adding more tidal channels. Placement of large trees and big tree root balls will increase cover for rearing fish, create habitat structure, and in the long term will act as nurse logs for the growth of Sitka spruce and other plant species.
Extensive seeding and planting of native plants will also occur to provide habitat structure for both fish and wildlife, and bring back declining forested tidal wetland habitat types unique to the Oregon Coast— commonly called crabapple bogs and spruce swamps.
Historically 40% of the Yaquina’s tidal wetlands were composed of these habitat types, but today only 10% remains. Long after the work is completed, MCWC and partners will monitor the effectiveness of the restoration work, including how vegetation composition changes, how fish utilize new tidal channels, and how much sedimentation build up is occurring.
BCI Contracting, Inc. will be conducting the project work.
“We were very impressed with BCI’s proposal to complete this project,” said Hayduk. “They have a successful record of implementing similar projects on the Oregon Coast and have specialized equipment, including amphibious excavators, to minimize soil compaction and potential damage to the wetland.”
Funding for this work was received from the Oregon Watershed Enhancement Board, the US Fish and Wildlife Service National Fish Passage Program, with additional support from the Pacific Marine and Estuarine Fish Habitat Partnership and the Oregon Wildlife Foundation. Project partners include the City of Toledo, the Confederated Tribes of Siletz Indians, the Wetlands Conservancy, Pacific States Marine Fisheries Commission, Oregon Department of Fish and Wildlife, U.S. Forest Service, Bureau of Land Management and US Fish and Wildlife Service National Fish Passage Program.
Updates will be available as the project progresses at: www.midcoastwatersheds.org