Endangered coho salmon will soon have restored winter rearing habitat, thanks to a recently completed habitat enhancement project in Sonoma County’s Green Valley Creek watershed. NOAA Fisheries’ Restoration Center, California Department of Fish and Wildlife, Gold Ridge Resource Conservation District, and several other partners provided funding and technical assistance to build a 200-foot long side channel and wetland pond in Green Valley Creek. The project included modifications to the mouth of nearby Thomas Creek, the creation of an alcove, and the placement of large wood to provide over-wintering habitat for young fish.
The watershed once supported healthy off-channel habitats that slowed stream flows, but with development came straightened stream channels and faster flows. The Mediterranean-like climate of northern California means rain can be heavy in the winter and non-existent in the summer. Without the refuge of calm off-channel habitats, high stream flows created during winter rains overwhelm juvenile salmon that are rearing and feeding. The fish spend more energy working against the current and less energy foraging and growing. This translates into lower survival rates for an already endangered species.
Looking downstream into the newly implemented side channel with large wood structures. Photo: Joe Pecharich, NOAA Fisheries’ Restoration Center
Green Valley Creek was one of only two streams in the Russian River watershed to have a remaining population of coho salmon before the establishment of a multi-agency conservation program, the Russian River Coho Salmon Captive Broodstock Program. The lack of winter habitat was identified as the main factor limiting the recovery of coho in this watershed. Most of the Russian River, as well as the creek, have been impacted by rural development, agriculture, timber harvest, and flood control alterations.
Wetland pond feature which is adjacent to previous photo of the side channel. This pond will receive a generous planting of native wetland plants. Photo: Joe Pecharich, NOAA Fisheries’ Restoration Center
“Considering most off-channel habitats have been lost in the Green Valley Creek and Russian River watersheds, this project should provide very beneficial winter rearing habitat for salmon,” said Joe Pecharich, a Habitat Restoration Specialist with NOAA Fisheries’ Restoration Center.
Local biologists have a unique opportunity to observe how salmon will use the newly constructed side channel. They will use a PIT-tag detection system to monitor salmon overwintering in Green Valley Creek, getting a better picture of the number of fish entering and exiting the channel and the extent of time spent in the new habitat.
Data collected prior to the restoration project will provide biologists with a baseline of how many fish used the habitat prior to implementation of the project. When salmon return to spawn the following year, biologists will be able to evaluate which individuals used the new habitat and how many of them survived. The PIT-tag detection system is also capable of detecting non-natal salmon and steelhead from other watersheds that use this lower gradient habitat as refuge from the swifter flows of the mainstem Russian River.
After years of planning, which included design changes and engagement with landowners, the project was implemented this fall. The site will also be planted with native trees and wetland plants in the coming months. This restoration project, and the monitoring that is being conducted, will provide important insights that can be used to inform restoration approaches in other watersheds.
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