Reconstruction of century-old structure provides multiple benefits
Yet another hazard to migratory salmon will disappear soon, when local, state, and federal officials finish building a permanent, fish-friendly weir in the Yolo Bypass four miles northeast of Woodland.
The Wallace Weir Fish Rescue project will help prevent adult Sacramento River salmon from swimming into a drainage ditch that leads deep into farm fields where spawning is hopeless. By building a permanent barrier across the Knights Landing Ridge Cut, the agencies will be able to better control farm drainage releases to avoid attracting salmon. A new fish collection facility adjacent to the weir will allow the California Department of Fish and Wildlife to more effectively capture stray salmon and return them to the river to spawn.
The Wallace Weir Fish Rescue project complements the work done last year by many of the same agencies to block fish at the nearby Colusa Basin Drainage Canal, which empties into the Sacramento River near Knights Landing. The idea behind both projects is the same: Keep adult salmon from straying out of the Sacramento River in order to boost the odds that those salmon will successfully spawn – and do so without compromising the ability of local farmers to maintain irrigation water levels and manage floods.
The Wallace Weir Fish Rescue project is within the Yolo Bypass, a wide swath of farmland that provides Sacramento and other cities relief from floods on the Sacramento River. The Bypass also is home to a wildlife refuge and a planned large-scale floodplain habitat restoration project.
“Reclamation District No. 108 is honored to be part of this team,” said RD 108 General Manager Lewis Bair. “We donate our time and expertise in this partnership because it exemplifies the ‘just fix it’ approach. There is growing hope in our community that hard work and strong partnerships will bring sustainability to both California’s fish and farms.”
RD 108 is managing the Wallace Weir Fish Rescue reconstruction project. Last year, RD 108 also managed the retrofit of the Knights Landing Outfall Gates. Reclamation District 108 provides flood control, irrigation water and drainage to 75 square miles of farmland in Colusa and Yolo counties.
The $13 million cost of the Wallace Weir project is being paid by the customers of the State Water Project, operated by the state Department of Water Resources, and the Central Valley Project, operated by the U.S. Bureau of Reclamation. The Wallace Weir Fish Rescue project is required by the National Marine Fisheries Services, which is responsible for protecting chinook salmon under the U.S. Endangered Species Act.
“The new permanent Wallace Weir and fish collection facility will allow hundreds of additional adult salmon to reach their spawning grounds, including critically endangered Sacramento River winter-run Chinook salmon,” said Maria Rea, Assistant Regional Administrator for NOAA Fisheries California Central Valley Office.
RD 108 hopes to finish the Wallace Weir project this winter. The permanent structure involves a new earthen weir hardened to withstand floods, as well as a pneumatically operated water control gates and an adjacent fish collection facility. Fish and Wildlife workers can safely capture and return any stray salmon back to the Sacramento River.
Since around 1916, Wallace Weir has been a temporary, 450-foot-long earthen berm scraped together by landowners to hold back water in the drainage ditch called the Knights Landing Ridge Cut. Winter storm runoff often breaks through the earthen berm and allows salmon to stray into the Ridge Cut. The Ridge Cut does not provide a reconnection back to the Sacramento River. In past years, including 2014, state biologists have attempted to rescue salmon that strayed into the Ridge Cut, but the rescue efforts are inefficient and stressful for fish, significantly reducing their chance of successfully spawning.
Both the Knights Landing Outfall Gates and Wallace Weir fish passage projects are integral to achieving Governor Edmund G. Brown Jr.’s direction to state agencies to begin restoration of at least 30,000 acres in the Sacramento-San Joaquin Delta over the next five years. They also help advance the Brown Administration’s five-year Water Action Plan, which calls for elimination of barriers to fish migration, and the Sacramento Valley Salmon Recovery Program, which is a comprehensive effort by the Northern California Water Association, Sacramento River Settlement Contractors, the Nature Conservancy, American Rivers, and California Trout to help recover salmon.
“A year ago near Knights Landing, we launched the first of many steps we are taking to improve the migration of salmon to and from the Pacific,” said California Department of Fish and Wildlife Director Charlton H. Bonham. “Today we’re taking another step here at Wallace Weir. Project by project, with cooperation as the key, we’re making the remarkable journey of Central Valley salmon safer.”
The fish passage improvements also will help irrigators better control water levels in the Knights Landing Ridge Cut and improve the chances for large-scale habitat restoration in the Bypass, a 92-square-mile swath of farmland and wetlands that operates most winters as a floodplain and wintering habitat for migratory birds. Most of the Bypass is privately owned and farmed, and the state holds easements that allow for regular flooding of the land. Local, State and federal proponents are optimistic that carefully planned ‘ag friendly’ changes in the Bypass to allow for more frequent flooding of longer duration can help endangered fish species by boosting food production and sheltering them from predators. Opportunities also exist to enhance flood protection and recreation for surrounding communities.
“There is active collaboration throughout the Sacramento Valley to creatively manage our precious water resources for the benefit of salmon and to further develop projects that provide multiple benefits for people and our special environment in this region,” said David Guy, President of the Northern California Water Association. “The Wallace Weir in the Yolo Bypass is another positive and exciting step forward in the efforts by local, state and federal agencies to work closely together to help recover salmon in the Sacramento Valley.”