The recommendation from the U.S. Fish and Wildlife Service and National Marine Fisheries comes as pressure is growing for the federal government to resolve bitter battles over sharing scarce water between farms and fish in the Klamath Basin, which was once the third-largest salmon producer on the West Coast.

Farmers and fishermen have suffered tens of millions of dollars in lost crops and catches, and Indian tribes have lost access to salmon that are an important part of their culture as well as their diet.

After the third straight year of dangerously low returns of fall chinook salmon to the Klamath, the Pacific Fishery Management Council will decide next week whether to shut down sport and commercial salmon fishing on 700 miles of the West Coast off Oregon and California.

The dams' owner, PacifiCorp, made no provision for salmon passage in its license application. Fish ladders are stairs that help adult salmon swim over dams, while the screens keep young salmon from swimming into turbines that can kill them. The cost of the recommendation would be about $200 million.

PacifiCorp is considering its options for appealing, said spokesman Dave Kvamme. The utility can challenge the validity of the recommendation as well as offer cheaper alternatives, such as trapping fish and hauling them around the dams.

The agencies noted that their proposal won't solve all the problems caused by the Klamath Hydroelectric Project, but they hope ongoing talks between PacifiCorp and interest groups could find better remedies. The agencies urged FERC to evaluate alternatives that include removing the dams.

Steve Thompson, head of the California-Nevada office of Fish and Wildlife in Sacramento, Calif., said dam improvements would be an important step in a larger effort to resolve environmental problems in the Klamath Basin.

"I am increasingly encouraged that the people of the Klamath Basin - farmers, tribes and fishermen alike - have joined together to see if they can make that happen,'' Thompson said in a statement.

Based in Portland, PacifiCorp produces electricity for 1.6 million customers in Oregon, California, Washington, Idaho, Utah and Wyoming. It was recently purchased by MidAmerican Energy Holdings Co. of Des Moines, Iowa.

The four Indian tribes on the river - the Klamath, Karuk, Hoopa and Yurok - praised the recommendations, saying they could ultimately lead to a decision by FERC or PacifiCorp to remove the dams.

"I think this is a watershed moment because now the economics start to change,'' said Craig Tucker, Klamath project coordinator for the Karuk tribe. "Fulfilling these conditions is not going to be cheap and makes dam removal a more viable economic alternative.''

Salmon in the Klamath have been beset by problems for more than a century. Gold mining in the 1850s caused extensive erosion that silted over spawning beds. In the early 1900s, a federal irrigation project diverted water from the river. The first of the dams was completed in 1918 with no fish ladder, permanently shutting off access to the upper basin.