The Klamath River once supported the third-largest salmon runs on the West Coast. But the river has become so shallow, warm and polluted that the once abundant runs have declined to the point of prompting the federal government to practically shut down commercial fishing on the West Coast.

Many factors have contributed to the Klamath's plight, including excessive irrigation withdrawals, agricultural runoff, logging, grazing and gold mining. But the greatest threat to salmon is a series of four power-generating dams owned by PacificCorp, which is struggling to secure a new 50-year license to operate the dams.

In a decision that could trigger removal of the dams and provide a breakthrough on one of the West's greatest environmental challenges, federal fish agencies said earlier this week that the utility must make costly improvements to allow salmon passage before its license is renewed.

The cost of those improvements - which include fish ladders, turbine screens and fish bypasses - has been estimated at nearly $300 million. Since removing the dams would only cost two-thirds that amount, the obvious choice for the utility is to abandon the relicensing effort and begin the complex process of shutting down the power plants and breaching the dams.

Demolition of the Klamath dams would be a historic move - the first time that four hydroelectric dams have been removed from any river in the United States or, for that matter, anywhere in the world.

Dam removal also would be a welcome development for Klamath salmon, prompting what fish biologists predict would be a dramatic revival of the species, as well as the fishing industries, coastal communities and Indian tribes that historically have depended on it for survival.

Momentum for dam removal has been building since last year, when the National Oceanic and Atmospheric Administration's National Marine Fisheries Service concluded that removal would be in the best interest of salmon. PacificCorp has stated publicly that it's open to removing the dams "as long as our customers are not harmed and our property rights are respected."

The four dams produce electricity for 70,000 PacificCorp customers and generate nearly $30 million a year. The loss of any power from the Northwest grid should not be minimized, but the Klamath dams are relatively small power producers. They produce a combined total of 150 megawatts, which represent only 1.7 percent of PacificCorp's overall output. The utility should have little difficulty replacing that output, particularly if Oregon and California provide help in the form of tax credits and production subsidies.

After decades of debate over the future of the Klamath, it's increasingly clear that the best outcome, both economically and environmentally, is to remove the dams and to allow salmon to swim freely in what eventually could be one of the nation's healthiest and most productive rivers.