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The Anadromous Fish Restoration Program aims to double the natural production of anadromous fish (fish that spend their adult life in oceans and return to the rivers to reproduce) like Chinook salmon and steelhead. The lower Yuba River can host up to 20 percent of all salmon spawning in the Sacramento River tributaries, but these emerging young fish face many challenges reaching the ocean. The primary focus of this project is to enhance productive juvenile salmonid rearing habitat, to allow juvenile fish to grow larger prior to their migration to the ocean, which will increase their chance of returning as adults. The U.S. Fish and Wildlife Service is funding the design and implementation of the Hallwood Project.
The floodplain surrounding the more than three miles of perennial side channels and four miles of seasonal side channels will inundate continuously for several weeks approximately every two years with shallow slow water favorable for juvenile salmonids. Groundwater-fed perennial side channels will stay connected all year, while seasonal side channels will inundate with typical spring flows to provide off-channel rearing habitat for juvenile salmonids.
The project will improve more than 170 acres of seasonally inundated riparian floodplain habitat for numerous riparian tree species, and the host of aquatic and terrestrial organisms that reside in these habitats. This project increases the connectivity of these habitats for a healthier, more productive river system; a resource benefit to the public for purposes such as aesthetics and recreation.
Pre-project monitoring began in 2014. Following that, snorkel surveys were conducted and macroinvertibrates (aquatic bugs) and water temperature were monitored from 2014 - 2016. Riparian vegetation composition and recruitment, and dissolved oxygen and turbidity grab measures were performed in 2016. Pre-project monitoring studies designed to compare fish health in off-channel habitat to the main channel, using juvenile outmigration and predation experiments, were performed in spring 2016. As part of implementation, physical and biological variables such as these will be monitored into the future to assess the project's effectiveness and learn lessons for future projects like this in the Central Valley.
This is the first project of its kind on the Yuba River, but similar actions have been take on other rivers in California. For example, on the Merced River, floodplain grading to create spawning habitat has led to high levels of spawning and floodplain utilization by juvenile salmonids. Additional projects on the Trinity, Stanislaus and American rivers have also improved main channel, off-channel and floodplain habitats for salmonids.