Cornell Experts: Quagga Mussels Threaten Water, Electric Plants

Fingernail-sized quagga mussels have spread to the West and tend to favor pipe intakes, where they can disrupt water flow, according to Chuck O'Neill, a senior extension associate with Cornell and New York Sea Grant.

O'Neill offered testimony to the U.S. House of Representatives Committee on Natural Resources Subcommittee on Water and Power on June 24. He discussed the economic and infrastructure impacts of both zebra and quagga mussels.

Quagga mussels showed up in the Great Lakes in the early 1990s. Last year, quaggas were discovered in Nevada's Lake Mead and have since been found down the Colorado River in Lake Mojave, Lake Havasu, and in various California locations.

Both quagga and zebra mussels originated in Eurasia in the Caspian, Ural, and Baltic seas and spread to the United States in ballast water from freighters.

Quagga mussels can feed on bacteria smaller than 15 microns and out-compete their zebra relatives. In both species, mature females produce up to 1 million eggs at a time that turn into free-swimming larvae called veligers. Two to five weeks after hatching, veligers become too heavy to float and search for hard surfaces to attach themselves. Water-intake pipes and similar structures offer ideal habitat because the continuous flow of water provides steady food and oxygen and carries away waste; the structures protect the veligers against predation, silt, and waves.

As mussels line a pipe or tunnel, they disrupt water flow. A single layer of mussels, 0.1 inches thick throughout a pipeline, can decrease water-carrying efficiency by 5 to 10 percent, said O'Neill.

In extreme cases, researchers have measured foot-thick colonies at the bottom of Lake Erie. Great Lakes intake canals have held 2- to 3-inch-thick colonies with three-quarters of a million mussels per square meter.

Among O'Neill's recommendations were immediate monitoring of critically important bodies of water and implementing short-term and long-term preventive measures by owners of pipelines.

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