Dozens of Chinook salmon were rescued Wednesday from a dead-end journey into the Yolo Bypass, the latest of their species to be fooled by a plumbing problem that has gone unfixed for decades.
Fall-run Chinook salmon regularly stray into the bypass, a massive flood-control channel paralleling the Sacramento River, at its downstream end near Rio Vista during their annual spawning migration. The fish continue swimming miles upstream through irrigation ditches in the bypass. They soon become trapped because there is no way to swim out of the bypass at its upstream end, where it rejoins the river, except during very high river flows.
“There’s actually more (salmon) in the system than we can handle right now,” said Colin Purdy, an environmental scientist with the California Department of Fish and Wildlife.
In January, Purdy’s agency placed a giant funnel-shaped trap – about the size of a small school bus – into the Knights Landing Ridge Cut north of Woodland in Yolo County. This canal drains agricultural runoff from the west side of the Sacramento Valley into the Yolo Bypass. The steel-mesh trap collects some of the salmon lured upstream by water flow in the canal.
The salmon are netted from the trap and tagged. They are loaded 12 at a time into a tank of water on a trailer, and released into the Sacramento River just a few miles away. The wildlife agency has been collecting as many as 80 adult salmon every day over the past few weeks as the fall salmon run enters full swing. More than 500 have been relocated since August.
Earlier this year, the trap also collected numerous spring- and winter-run Chinook salmon, which are protected as endangered species. In 2013, about 600 winter-run salmon were found trapped in agricultural canals farther north, amounting to about 10 percent of the run that year.
The Department of Fish and Wildlife has spent about $50,000 on the rescue program since August, spokeswoman Janice Mackey said.
“On an annual basis, we lose a lot of fish to these canal systems,” said Jacob Katz, regional program manager at CalTrout, a fisheries advocacy group. “It’s been happening since the canals were built 100 years ago. It’s something we need to fix now.”
The California Department of Water Resources and U.S. Bureau of Reclamation, which operate major dams and water diversion systems in the Valley, are required by the Endangered Species Act to improve fish passage in the bypass. But the solution is taking time. A draft environmental impact study on their proposal is not expected for release until 2017.
“This is on the top of everybody’s project list,” said John Brennan, owner of Robbins Rice Co., a farming company that owns land in the bypass where the salmon were collected Wednesday. “The problem is, the government wants to master-plan everything and get everyone on board before they do anything.”
Brennan and CalTrout have proposed a simpler, interim solution. It would involve installing a small weir, or dam, across the entrance to the Knights Landing Ridge Cut to block salmon from entering; excavating a channel across the Yolo Bypass to divert water flow – and salmon – in the proper direction; and building a new fish ladder at the upstream end of the bypass.
This fix, Brennan said, would allow salmon and other fish to move on their own through the bypass and back into the Sacramento River, even under normal river flows. The estimated cost: about $5 million.
Meanwhile, the Department of Fish and Wildlife continues collecting stray salmon as it can. The trap will remain in place through the duration of the winter. Each captured salmon is counted and tagged, so if it is ever seen again – on a hook or in a hatchery – its travels can be tracked.
Purdy said all this data will help inform any eventual salmon migration fix in the bypass.
“We’re working with our state and federal partners to come up with a long-term solution,” he said. “It’s not an easy fix, though.”
The Sacramento River’s fall-run Chinook salmon is the species that ends up on restaurant menus and supermarket shelves as “wild-caught” California salmon. That supply depends on how many fisherman can catch. In turn, fishing regulations determine the catch limit based on the number of salmon that complete their spawning run, said John McManus, executive director of the Golden Gate Salmon Association, which represents commercial anglers.
“Our fisheries are constrained by numbers,” said McManus, who watched a big salmon thrashing in a tub as it was measured and tagged. “So it’s crucial that we don’t lose a one of them in an agricultural drainage ditch, especially when it’s preventable.”
Call The Bee’s Matt Weiser at (916) 321-1264. Follow him on Twitter @matt_weiser.