Invasive mussels pose threat to dams

SPOKANE — The expected arrival of invasive mussels in the Columbia River Basin could cost $100 million a year to fight, according to a new report done for the Northwest Power and Conservation Council.

The dime-sized freshwater mussels pose a threat to dams, irrigation systems and native fish species, said the report from a panel of economists.

"While the mussels have not infested the Columbia River Basin yet, it may be just a matter of time," the council said in a statement, adding that efforts should still be made to stop or at least delay an invasion.

Council Chairman Bruce Measure said the report shows a rapid response and public education are critical to that effort.

Quagga mussels and their close cousin zebra mussels were introduced to the Great Lakes in the ballast of ships from Eastern Europe and the Ukraine in the 1980s. They have spread and caused millions of dollars in cleanup and repair costs in the Northeast, Midwest and Southwest.

The best deterrent is a combination of watercraft inspections, public information and continued scientific research, the report said.

Eradicating the mussels is virtually impossible. They attach to almost anything and can clog drains and pipes, freeze up cooling systems, kill off native species and render power boats inoperable.

In the Columbia River Basin, the new report estimated costs of cleaning water intakes and related equipment at federal hydropower dams on the Columbia and Snake rivers at $16 million a year, plus $5 million a year for other dams.

Cleaning spillway gates, fish-bypass screens and related equipment would cost about $3 million to $10 million a year at the federal dams. Replacing filtration systems at 20 fish hatcheries would cost $1 million each.

Cleaning recreation facilities, including water supplies, docks and boats, could run $50 million or more a year.

The mussels are transported between water bodies on boats and other watercraft that are being moved by trailer. They are capable of living out of water for days.

Boat-inspection campaigns are already under way in each of the four Northwest states, and several infested boats have been stopped and cleaned entering Idaho and Washington from infested lakes in the Southwest.

Calcium concentrations in the water appear to be important in determining whether the mussels can reproduce, as they absorb the mineral to make shells.

In much of the Columbia River and its tributaries, calcium levels probably are too low for mussels to thrive, the report said.

An exception is the upper Snake River drainage in southeastern Idaho, where calcium levels are often ideal for mussels, the report said.