Exotic mussels found at water plant

Times Staff Writer

A destructive mussel found earlier this month in Lake Mead now has been discovered at intakes for the aqueduct system that carries water from the Colorado River to Southern California, raising fears that the invasive species could inflict costly damage to pipelines, aquatic life and waterways in California.

Officials said Friday that bivalve mollusks collected by Metropolitan Water District divers Wednesday were determined to be quagga mussels, which are native to Eastern Europe and have spread across the United States along with their troublesome relative, the zebra mussel.

The infestation discovered Jan. 6 in Lake Mead near Las Vegas was the first in the West. The mussels found last week at an MWD plant at Lake Havasu and a pumping station two miles to the west were the first confirmed in California. A single quagga mussel was found Friday by California Department of Fish and Game divers about 14 miles away on the Colorado River.

“We do not feel there is any danger or impact to the safety of drinking water supplies,” MWD Chief Operating Officer Debra Man told a teleconference. “It is something we ... want to ensure does not spread.”


For years, wildlife and water officials in the West have been concerned about the possible arrival of the quagga mussel, which was discovered in the Great Lakes about 20 years ago and later spread to the Mississippi River.

The prolific quagga mussels cluster by the millions and feed voraciously on phytoplankton, creating organic waste products that eat up oxygen and release toxic byproducts. Colonies of the mussels clog water intakes and outfall pipes and leave fewer nutrients to support the food chain of fish.

The mussels can spread by attaching themselves to boats or floating objects, or their larvae can drift downstream. Officials say there is no known way to eradicate the mussels, so they can only try to contain them to prevent costly problems or an unpleasant odor and taste in water supplies.

Ric De Leon, MWD’s microbiology manager, said that chlorination can kill the larvae and that copper sulfate can be applied to adults. But he said that the mussels also can be killed by drying them out -- and that a three-week scheduled maintenance shutdown in March will provide that opportunity.


De Leon said most parts of the 242-mile aqueduct can either be drained or treated with chemicals.

MWD officials were encouraged that adult mussels apparently had not reached one of their facilities about 10 miles from Lake Havasu. But a multi-agency task force is continuing to investigate to determine the extent of the infestation through inspections, diving and testing.

MWD spokesman Bob Muir said the agency plans to increase boat inspections at its recreational reservoirs, including Diamond Valley Lake in Riverside County.

“This is not the first time we have dealt with a nuisance species on the Colorado River,” he said. “We have controlled Asiatic clams