Invasive Mussels a Costly Problem for Water Authorities

An animal the size of a human fingernail is causing multimillion dollar problems in a growing number of waterways, pumping stations and hydroelectric power plants-including the Hoover Dam. 

Quagga and Zebra mussels, tiny tan colored mussels with black stripes, first made their way to America in the early ’90s by way of a European cargo ship. They quickly made a home for themselves in Lake Erie. What many didn’t know then was that the species, known for rapid reproduction rates of up to one million eggs per female, is invasive and poses a multitude of threats to the already fragile ecosystems they inhabit.

Today Lake Erie’s “dead zone,” an area without sufficient oxygen and food supply for other animals, is growing larger partially because of the mussels’ year-round feeding and waste patterns.

The problem that began in the Great Lakes region has made its way to Western states with Arizona, California and Nevada water authorities reporting growing mussel populations in their lakes and reservoirs.

The mussels hitchhike between bodies of water, flowing downstream to attach themselves to hard surfaces, including boat hulls. For years, this has left vacationers at risk of accidentally bringing the problem home wherever they typically sail. The mussels also suction themselves to the interiors of water pipes and clog them, resulting in ecological damage and higher recreation costs in the way of taxes and fees specifically set aside to deal with the pests.

The prospect of overland travel by the mussels caused Santa Barbara County in California to implement boating charges for research of the animals’ effect on waterways, and on the economy.

Now, out-of-state visitors-and in-state visitors from infected lakes such as Lake Havasu-will have their vessels “quarantined on site” for two weeks to be inspected and cleared for launch on the man-made Cachuma Lake, on the Santa Ynez River north of Los Angeles.

In Oregon, boaters are now required to pay a biannual fee ranging from $5 to $7 on top of registration fees to help fund the search and removal of the pests in the state’s waterways. Out of state boaters are required to pay $22 and the state estimates it will raise $3 million in fees over the course of two years, according to the Seattle Times.

California’s Lake Havasu, which serves as a border with Arizona in the Southeastern tip of the state, was infested with the mussels one month after Lake Mead in February of 2007. Since then, infestation densities have ballooned from one to two mussels per square meter to 10,000 per square meter in some places.

Nevada’s Lake Mead, the largest reservoir in the U.S. which supplies 90 percent of the Las Vegas Valley’s water, became infested with the mussels in January of 2007, said Ronald Zegers, former director of the Southern Nevada Water Authority.

“The Quagga mussel has become arguably the most serious non-indigenous biofouling pest ever to be introduced into North American freshwater systems,” he said.

In addition to being serious problem, the mussels appear to be a costly one as well.

Nevada’s short term solution, adding chlorine to the intake pumping plants, is projected to cost the SNWA between $1 and $4 million. The longer term resolution the authority plans to use calls for chlorine pumps to be embedded in new water intake pumping plants, which is projected to cost around $20 million.

Mussels clogging filtration pipes and hampering electrical output has meant more work for less service at affected pumping stations and power plants.

Dr. Charles O’Neill Jr., of the New York Sea Grant, a network of researchers dedicated to ecological stewardship of the Great Lakes, said the additional costs are simply being passed on to the marine industry, customers and vacationers.

“Drinking water continues to flow at consumers’ taps, the lights and air-conditioning still work, and products continue to be manufactured, but not without a significant cost to the infrastructure owners and operators and to their customers,” he said.

O’Neill performed a cost analysis of the issue and determined that between prevention efforts, lost pumping productivity for drinking and electricity and other environmental cleanup initiatives, each water facility in the state of New York alone loses upward of a half million dollars annually because of mussel infestation.

The Hoover Dam, which supplies power to millions in Nevada, Arizona and California, was recently shut down temporarily because waterlines used to cool hydropower turbines had become clogged with the mussels, according to a New York Times report. 

In an effort to combat the invasive species, the U.S. Bureau of Reclamation has formed a task force specifically dedicated to research and removal of the mussels.

“In the end, national, regional, state and local efforts to prevent and combat invasive species like the Zebra mussel are suffering from a lack of resources,” he added.


Last summer, Zegers testified in front of Congress to let representatives know how severe the problem has gotten, and to try convincing Congress to fund some invasive species containment and eradication efforts. He said financing the control of the aquatic pests is still being left up to individual water control agencies and the customers they serve.

“Now [federal government agencies] are helping with respect to doing scientific research to help protect infrastructure,” Zegers said.

But research still does relatively little to deal with the estimated 500 mussels per square meter already living and quickly reproducing beneath the surface of Lake Mead, clogging water filter screens and intake pumping valves.

With the federal  government still not funding programs to alleviate the costs of removing and preventing further spread of the Quagga and Zebra mussels, the costs of dealing with the animals’ impact continues to grow for the marine industry and consumers as the animals find new homes and continue to multiply.