Thomas Creek Family Forest Fish Passage Project

Wild Fish Conservancy (WFC) performed this fish passage project on Thomas Creek, a tributary to the Green River in western Washington State, where it passed under a driveway through two undersized culverts that block coho, cutthroat, and other native fishes from accessing 2.6 miles of vital stream and wetland habitat. By interrupting habitat connectivity, even a single barrier can have a disproportionately large impact on the abundance and resiliency of wild fish populations.

Man-made barriers to fish migration have significant impacts on wild fish; limiting distribution, reducing access to spawning and rearing habitats, and disrupting the spatial habitat complexity historically available to fish populations. Whether for resident species that spend their entire lives in one watershed, or migratory species that travel thousands of miles, instream barriers compromise a populations’ ability to weather environmental uncertainties. Evolutionary fitness of the entire population is weakened when barriers restrict gene flow, creating small, isolated sub-groups that can suffer from inbreeding.

The Family Forest Fish Passage Program (FFFPP) assists private forestland owners in removing culverts and other stream crossing structures that prevent salmon from migrating upstream. Through the management of DNR’s Washington State Recreation and Conservation Office some 376 landowners have utilized of the program to remove 433 fish passage barriers since 2003.

WFC staff replaced the two failing culverts with a 10-foot span, 12-foot long, 5-foot high precast concrete box culvert that provided a huge increase in flow capacity and enabled wild fish to access critical spawning and rearing habitat upstream from the project site.

While wrapping up the associated riparian planting during the winter of 2011, WFC crew spooked an adult coho out of the culvert and she swam upstream. She was just one of thousands of salmon we expect will benefit from the project over the 50+ year lifespan of the new box culvert.