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Report: Mussel Invasion In Upper Snake Likely

by Staff
Columbia Basin Bulletin, July 16, 2010

Economic Risk 'Hundreds of Millions of Dollars Annually'

(U.S. Fish & Wildlife Service) Quagga mussels like these can quickly clog pipes and other infrastructure. The non-native species hasn't arrived in the Northwest yet, but it's expected to complicate salmon recovery when it does. The total estimated cost of a zebra or quagga mussel invasion of the upper Snake River is subject to much uncertainty, but one thing's for sure -- it won't be cheap, according to an economic report released Thursday.

"It would cost hundreds of million of dollars annually if they became established and thrive," economist Noelwah Netusil told the Northwest Power and Conservation Council in describing a worst-case scenario outlined in the report.

"Economic Risk Associated with the Potential Establishment of Zebra and Quagga Mussels in the Columbia River Basin" was produced by the NPCC's Independent Economic Advisory Board in collaboration with regional mussel and water quality experts and others. Primary author is IEAB Chair Roger Mann.

The report can be found at

In its key findings the IEAB advises that delaying what is a "likely" invasion of the upper Snake is advisable. Time would allow the development of science regarding control technologies and for the planning for potential responses to infestations in order to hold down costs. Delaying an invasion of mussels would also delay the costs that they would impose.

"In the short run, prevention buys time that can be used to prepare," the report says.

Programs for preventing an invasion are under funded, the report says. State budgets total about $3 million annually.

"The IEAB believes that the annual cost of a mussel infestation could be hundreds of millions of dollars annually, so assuming that additional expense can delay an infestation, this appears to be a good investment, at least until science issues are resolved," the report says.

The zebra mussel and quagga mussel are two species of invasive bivalve mollusks native to the Black-Sea-Caspian Sea-Ukraine region that were accidentally introduced into the Great Lakes region of the United States in the 1980s.

Both species have steadily expanded their continental range. Zebra mussels now occupy most of the Mississippi and some Missouri river basin states, as well as selected sites in California, Utah and Colorado. Quagga mussels occupy a more restricted range including several Great Lakes and Mississippi river states. They were found in Lake Mead in 2007 and have spread to other sites in the southwestern United States

The nonnative mussels are believed to be most commonly transported by attaching themselves to boats that are then trailered from one location to another.

"Because of their ability to attach to structures, both zebra and quagga mussels can present major problems for underwater facilities. They can foul pipes of hydroelectric facilities, water works, and other industrial facilities, including fish passage facilities, fish screens, fish hatcheries and aquaculture operations," the IEAB report says. "These highly invasive mussels can disperse and grow quickly and reach high densities, impairing facility functions and damaging ecosystems wherever they are established."

Scientists believe that the nonnative mussels need higher levels of calcium in the water to thrive -- a scenario that has played out somewhat drastically in the Great Lakes region and at Lake Mead.

Uncertain is how well the mussels might do in the calcium levels that vary by season and location in the Columbia-Snake river basin. Calcium levels in the mainstem Columbia and Snake river below central Idaho's Clearwater River are believed to be at levels low enough to discourage infestations.

"However, for much of the Snake River above the Clearwater River, some parts of the Salmon, John Day and Pend Oreille River basins, and other local areas, calcium conditions may be generally favorable for mussels," the report says. "Establishment and reproduction in these favorable locations could produce large numbers of veligers (free-floating juveniles) that could quickly establish themselves at other suitable locations downstream."

The economists developed the worst-case Snake River cost estimates because an infestation there is considered to be relatively likely. Once established there the mussels could send a steady stream of veligers downstream, where they could eventually get a foothold in locations where water conditions are less ideal.

The cost estimates summarize existing estimates for impacts on hydropower and fish passage facilities at dams, hatcheries, impacts on habitat and valuable species and water diversion and pumping facilities (including fish screens). The report emphasizes potential effects on facilities, resources, ecosystems and species that are closely related to the NPCC's Columbia River Basin Fish and Wildlife Program and the Federal Columbia River Power System.

". . . in the potential worst-case scenario, potential costs include some combination of hydropower production losses, cleaning and control costs, costs of redundant screens and new bypass systems, and an additional cost that should be assigned to any reduced juvenile survival," according to the IEAB report.

"Half of the value of hydropower production from the facilities is used to estimate an approximate upper bound ($250 to $300 million annually) on potential cost. The total potential cost of mussel fouling of juvenile passage systems is unknown, but could be in the tens to hundreds of millions of dollars annually."

Mussel-fouled habitat, and screens built to prevent fish from entering turbines and water diversions, would also bring huge costs.

". . . on the upper Snake River, where calcium is favorable and there are numerous irrigation diversions, additional cleaning costs and loss of screen protection can be expected. Substantial costs could also be incurred to maintain water supplies where mussels interfere with diversion, pumping, conveyance and distribution of water," the report says. "We build on cost estimates developed by IANST (2009) to obtain an expected annual cost of about $50 million. The possible range is tens to hundreds of millions annually."

"The potential costs, especially in the Snake River Basin, would likely involve habitat replacement, reduced chances for recovery of protected-status species, an increased chance of listing for other species, increased costs of compliance with endangered species laws, and reduced populations of other economically important species including game fish," the IEAB report says. "We assume that existing policies would require that anadromous fish and rare species populations be returned to their without-mussel status. The cost of this compensation is unknown, but could be tens to hundreds of millions of dollars annually."

The IEAB says that more biological analysis is needed to determine how variable calcium concentrations, calcium in the diet, pH, water velocity and temperature affect the mussels' ability to survive in different areas of the Columbia basin.

"Such research is important to refine the estimates of potential costs of mussel infestations should they occur," the IEAB said.

Report: Mussel Invasion In Upper Snake Likely; Economic Risk 'Hundreds of Millions of Dollars Annually'
Columbia Basin Bulletin, July 16, 2010

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