Mussels a threat to the Columbia River Basin

Portland State University researchers told the Northwest Power and Conservation Council on Feb. 13 that water chemistry and temperature in the Columbia River Basin are sufficient, if not ideal, to support invasive freshwater mussels.

The researchers have been studying the potential for invasive mussels to take hold in the Columbia River Basin as they have in lakes and rivers from the Midwest to the Southwest, causing untold damage to infrastructure and local ecology.

“This appears to confirm our fears that mussels would grow well in the Columbia,” council chairman Bill Bradbury said. “The results underscore the importance of the boat inspection programs and other efforts in our states to keep mussels out of Northwest waters.”

The mussels are transported from place to place primarily on infested watercraft. Dime-size zebra and quagga mussels adhere to boat hulls and submerged structures, including dams and dock pilings. The thick hard mats of shells block water passage and deplete nutrients for other species, ruining fish habitat.

The Council’s Independent Economic Advisory Board estimates that the cost of controlling an infestation and cleaning hydropower and fish-passage facilities could easily be in the tens of millions of dollars per year — and hundreds of millions in total costs to protect lakes and rivers, inspect and decontaminate infested watercraft, and address other impacts.

The research team focused on quagga mussels collected from a dock in Lake Mead, Nev., and submerged in buckets of untreated Columbia and Willamette river water. Then they gradually adjusted calcium concentrations and water temperature and observed how the mussels reacted.

“We found that 68 percent of the mussels raised in untreated Columbia River water gained weight,” researcher Brian Adair said. “This does not bode well for the Columbia.”

The researchers also tested several types of surface coatings to see how well they inhibited mussel growth. The coatings are not toxic but are expensive, costing about $130 per square meter. After three months, some products performed better than others, depending on the surface material, but quagga mussels could not adhere to any of the surfaces.

The experiment will continue until the panels have been submerged 15 months. The researchers then plan to conduct a similar test at the infested San Justo Reservoir, a Bureau of Reclamation project about 90 miles south of San Francisco. They will then prepare a cost estimate for treating a Columbia River hydroelectric dam.