A Sacramento federal judge has ordered interim measures to protect three threatened fish species on the lower Yuba River while the National Marine Fisheries Service drafts a new biology study that will satisfy the mandates of the Endangered Species Act.

In an order a year ago, U.S. District Judge Lawrence K. Karlton ruled that the fisheries service "acted arbitrarily and capriciously" in issuing a flawed 2007 study, called a biological opinion, that concluded the operation of two dams on the river poses no jeopardy to the survival of spring run chinook salmon, Central Valley steelhead and green sturgeon.

In April, Karlton told the agency to have a new biological opinion that conforms to his 2010 order by Dec. 12.

Meanwhile, in a 45-page order filed Tuesday, the judge directed the U.S. Army Corps of Engineers to:

• Come up with a written plan within six weeks that specifies how movable flash boards on Daguerre Point Dam spillway that act to concentrate flows away from the dam's fish ladders can be used to maximize fish passage.

• Conduct weekly manual inspections of the ladders for surface and subsurface debris during routine flows and, during flows of 4,200 cubic feet per second or greater, conduct daily inspections.

• Remove all debris within 12 hours of its discovery.

• Inspect the river upstream from Daguerre after a high-flow event and, if there is significant sediment buildup that might impair fish passage, dredge the channel.

• Install locking metal grates over the fish ladders to prevent fish from jumping out of the ladders and to prevent poaching.

• Develop a plan to separate spring chinook from fall run chinook, allowing the former to spawn without competition from or cross-breeding with the latter.

• Include in that plan a seasonal segregation weir below Englebright Dam, and also include measures to impede the migration of stray hatchery fish into areas where they might compete with spring chinook spawners and interbreed with spring chinook.

• Provide the plan with eight weeks for review and comment to the California Department of Fish and Game, the fisheries service, and two environmental groups suing the agency and Corps over fish preservation in the lower Yuba.

• Implement the plan when it is approved by the two federal agencies.

The South Yuba River Citizens League and Friends of the River had sought the interim measures to lessen the dams' adverse impacts until more permanent solutions are achieved.

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