Lower Coquille Restoration Effectiveness Monitoring

The Lower Coquille Restoration Effectiveness Monitoring Project (Project) will examine the effectiveness of two tidegate replacements and habitat restoration projects in the Coquille River (Coquille/Coos County). The project areas were historically freshwater tidal wetlands that were cleared, diked and drained for agricultural use, a fate typical of over-winter rearing habitat in the Coquille. The depletion of slow-water refugia has been identified as the primary limiting factor affecting the recovery of Oregon Coast coho. For this reason, tidegate replacements are currently ongoing across the coast but it is unclear how juvenile coho respond to the improved access and habitat enhanced behind upgraded tidegates. The proposed Project is part of CoqWA’s overarching Lower Coquille Tidegate and Fish Passage Monitoring Program. The goal of this Program is to work collaboratively to examine the functionality of individual tidegate projects and how their compounded uplift promotes recovery of the Oregon Coast ESU coho population. The primary goal for the Project is to improve our understanding of how juvenile coho respond to the varied sizes and complexities of new tidegates and the restored habitat. Additionally, we aim to inform adaptive management of the sites and provide critical information to maximize the effectiveness of future tidegate replacement and habitat enhancement projects. The goals will be achieved through three years of water quality sampling, fish sampling and Passive Integrated Transponder (PIT) tagging at the two project areas (located near river mile 13) and fish sampling and tagging in the Lower Coquille River (funded by a pending NOAA grant). Salmonid movement will be tracked by the installation of PIT antenna arrays on the two MTR tidegates at the two project sites. We intend to widely share results via written reports and through in-person presentations. Project Partners: landowners, ODFW (Charleston, Dalles Research Station, REDD Group) and DEQ.

The Oregon Coast has over a thousand tidegates and specifically the Coquille Valley contains over one hundred tidegates, many of which are failing. Many watershed councils along the Oregon Coast, including the Coquille Watershed Association, are optimizing tidegate replacements as “increasing overwinter rearing habitat is the top priority for ESU recovery” (ESA Recovery Plan for Oregon Coast Coho Salmon NMFS, 2016). Current tidegate replacement projects most often include restoration actions (e.g. channel construction and vegetation enhancements) for freshwater and saline tidal wetlands yet it is unknown how productive these restored wetlands are when located behind new MTR tidegates especially with respect to size of both tidegate installed and restored habitat. NMFS states in the ESA Recovery Plan for Oregon Coast Coho Salmon that a primary limiting factor affecting the Oregon Coast ESU coho recovery is overwinter rearing habitat specifically “connections to wetlands, backwater areas and complex floodplains”. Therefore, the importance of monitoring tidegate effectiveness is multifaceted and critical to improving the applied science of tideland restoration and tidegate upgrades and in turn all aspects benefit salmonids. In addition, by quantifying how much of an uplift the recent tidegate upgrades and habitat restoration projects have on the coho population of the Coquille Valley can in turn help inform future funders on the most beneficial actions and projects to take to recover Oregon Coast coho and other resources. Not only will an increase in habitat uplift be computed but the project will work to document changes in growth rate, survival and body condition based on restored estuarine-reared vs riverine-reared fish.
As noted in the Ecological Effects of Tidegate Upgrade or Removal (Souder, et al. 2018) “the information base on the effects of tidegate upgrades is limited.” Therefore, the results from our program will meet the needs identified in the ESA Recovery Plan for Oregon Coast Coho Salmon and Ecological Effects of Tidegate Upgrade or Removal and benefit the entire Oregon Coast in terms of providing critical and relevant information to agencies, landowners, and coastal communities on the effectiveness tidegate upgrades and tidal wetland restoration have on Oregon Coast ESU coho recovery.