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Mini-mussel menace assessed

Farmers in Santa Clara River Valley worry mollusks could threaten irrigation

Posted: January 20, 2014 7:49 p.m.
Updated: January 20, 2014 7:49 p.m.
Quagga mussels. Signal photo by Dan Watson Quagga mussels. Signal photo by Dan Watson
Quagga mussels. Signal photo by Dan Watson

SANTA CLARITA - Park officials aided by a university dive team have been assessing Lake Piru to determine the spread of the destructive quagga mussel, a tiny mollusk that some fear could endanger part of the Santa Clara River.

Divers from University California Santa Barbara’s Sea Grant Extension Program plunged into the lake Saturday and inspected weighted ladder-like monitoring devices at 20 locations, from the north end of the lake where the mussels were first discovered Dec. 18 to its dam on the south end of the lake.

The divers inspected 30-foot rope “ladders” fixed with plastic lids the size of frisbees, foot-long sections of 2-inch PVC tubing and a concrete anchor, sunk strategically around the lake in a bid to sample the entire body of water for quagga mussels.

“These are substrate settling devices that provide a surface for quagga mussels as they go from the plankton size to the shell size, the adult size,” said Clayton Strahan, who works for lake manager United Water Conservation District as the supervising park services officer for the Lake Piru Recreation Area.

“The quaggas like things with grooves, channels and places where they can get inside and settle. So these devices provide ideal habitat and surfaces for quagga mussels to attach to.”

“They allow us to track and observe where quaggas may be settling out throughout the lake and where disbursement may be taking place,” Strahan said of the “ladders” distributed in the lake.

So what’s so fearsome about a tiny mollusk? Quagga mussels, and their zebra mussel cousins, destroy aquatic ecosystems once they gain a foothold in a body of water. They enter pipes, filtering systems and other water-conveying equipment and clog the works, causing millions of dollars in damage to reservoirs, dams, pipelines, power plants and boats.

“There are concerns with farmers that it could plug irrigation lines,” said Strahan. The mussels reproduce in huge numbers and spread through the water as well as transferring from water body to water body on boats and other objects. They can survive dry conditions for three to five days.

Lake Piru empties into a tributary that feeds the Santa Clara River, which is used for irrigation of valuable crops throughout the Santa Clara River Valley to the Oxnard Plain.

The section of the river that could be affected is downstream from the Santa Clarita Valley, and Lake Piru is not part of the same water system that feeds Northern California water to the SCV and other Southern California cities.

However, Pyramid Lake and Castaic Lake are part of that water system. Watercraft allowed on those lakes is inspected for the freshwater mussels before it can be put in the water.

But boats allowed onto Lake Piru also have been inspected for the mollusks for more than five years, Strahan said.

“Population density is what we’re looking for,” Strahan said of the lake assessment. “We want to know how widespread is the infestation? Is it lake-wide? Is it only in certain areas? That way we can devise a management plan and/or eradication plan.”

“United (Water) is currently working on analysis of effluent leaving the lake to determine probability of the spread of quaggas from the lake, and at this time we do not have any idea or determination in this issue,” he said.

The Santa Clara River wouldn’t necessarily be a hospitable environment for the mini-mollusks, he said.

Prolonged dry conditions, as well as turbulence when the river does flow, could eliminate the river as a quagga-friendly environment, he said.
on Twitter @jamesarthurholt




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