By Paul Lebowitz

CALIFORNIA – Water officials have discovered non-native quagga mussels in several Southern California lakes. The tiny freshwater mollusks, no larger than the average fingertip, pose a devastating threat to the state’s freshwater fisheries and water supply infrastructure far out of proportion to their diminutive size.  

“From a fisheries standpoint, it’s about the worst thing that could happen to us,” said Hugh Marx, Supervising Ranger at Lake Jennings in San Diego County.

The invasive pests spread like a watery version of a wildfire, carried from lake to lake not by an ill wind but by boat. In the Great Lakes region they’ve clogged water pipes, damaged pumps, and complicated water treatment and delivery to the tune of billions of rate-payer dollars.

Boaters and anglers stand to lose more than their wallets; left unchecked, the quagga consume the plankton that fry and forage fish such as shad feed on, leaving an empty pantry for bass, trout and other gamefish.

The diminutive mussels aren’t much to look at, but they pack a powerful reproductive punch. A single brown and white striped female can produce a million offspring each year.

Marx said the bivalves have been found in concentrations of up to 50,000 per square yard in the Great Lakes, each filtering the food out of a liter of water per day.

“Fish populations crash because the mussels eat the same plankton as newly hatched fish” Marx said.

Once introduced, quagga mussels are incredibly difficult to eradicate. They have no natural predators in North America. The most practical control methods are prolonged desiccation (five full days without water in the heat of the sun), hot water exposure (140 degrees and up), and treatment with chlorine.

As evidenced by their jump from the Great Lakes, where the Asian immigrants got their first foothold in North America, to Lake Mead in the desert-bounded Colorado River system, quaggas are nightmarishly easy to spread unintentionally. All it takes for microscopic quagga larvae to hitchhike to an unaffected lake or river is a little bit of contaminated water left in a boat engine, a bilge, or livewell.

“When I heard they had four year old mussels in Lake Mead I knew it was all over,” said Marx, who predicted the quaggas would continue their westward migration until they reached California. He was right.

In summer 2007 quagga mussels were discovered in several Southern California reservoirs connected to the Colorado River system: lakes Matthews and Skinner in Riverside County; and Dixon, Lower Otay, Miramar and San Vicente in San Diego County.

SMALL MUSSELS POSE A HUGE PROBLEM – Invasive quagga mussels have been discovered in several Southern California lakes, all connected to the Colorado River system. By dint of their supercharged reproduction, the tiny bivalves threaten to eat lakes empty while coating every available hard surface. PHOTO COURTESY DFG

CLEANING OFF QUAGGA – Boaters can help check the spread of quagga mussels by giving them nowhere to stow away. Carefully check the indicated locations, being sure to drain all water from the engine, bilge and livewells. Quagga mussels too small to see feel like sandpaper to the touch. ILLUSTRATION COURTESY DFG

It doesn’t take a great leap of faith to assume they’ve infiltrated other waters in the giant imported water delivery system, such as Perris, Diamond Valley, and others.

To date, quaggas haven’t turned up in any local waters cut off from the Colorado. Examples include Wohlford and Cuyamaca. Nor have they been found in the canals and lakes fed by the State Water Project. Water managers and state wildlife officials want to keep it that way.

Ultimately, preventing the spread of quagga comes down to controlling and limiting boating, the likeliest means of moving mussels between watersheds. At a minimum, boaters face the inconvenience of inspection and decontamination; in the worst case, some water managers may determine the only defense is to close their lakes to private boats.

Escondido has already done so at Lake Wohlford. The ban was lifted for a short time when lake staff began pressure washing incoming private boats using borrowed equipment, but was reinstated only days later when the cleaning equipment broke. Wohlford management also pointed to non-compliant boat owners, a few of whom dodged the treatment area and launched potentially contaminated vessels at unapproved sites. Cuyamaca quickly followed suit.

At Lake Poway, float tubes, private motors, anchors, live bait containers, and live bait in water are now prohibited. The lake was already closed to private boats.

Elsewhere officials are still scrambling to develop rules and regulations to combat the quagga. Boaters should expect power washing and equipment prohibitions to become commonplace.

Alexia Retallack, the California Department of Fish and Game’s quagga spokesperson, said the state agency is formulating boat decontamination protocols. In the meantime, DFG officials are asking boaters moving from lake to lake to thoroughly inspect, clean and dry their vessels.

“Check the wheel wells, check for standing water, and drain the bilge, engine and livewell. Get the water out of the boat,” Retallack said.

Carefully inspect the boat. Immature mussels can’t be seen without a magnifying glass but they can be identified. They feel like sandpaper to the touch. 

Boaters who discover quaggas should use a pressure washer heated to 140 degrees or higher to blast the mussels. Don’t do it anywhere near a storm drain Retallack reminded.

Store a boat high and dry for five days before visiting a new lake.

The boat cleaning process is inconvenient but critical said Retallack. It is in a boater’s self interest too.

“Every recreational boater should care. Quaggas can ruin a boat,” Retallack said.

Marx feels slowing and controlling the spread of quaggas will be a challenging task for the state and its angling and boating communities.