....Outdoors: Tiny species of mussel could wreak havoc with California's lakes and waterways
Tom Stienstra, SF Chronicle Outdoors Writer
Wednesday, April 2, 2008
(04-02) 20:57 PDT -- The biggest threats that California's lakes have ever faced are no larger than a small thumbnail.
Tiny quagga and zebra mussels are an invasive species that represent an environmental nuclear bomb for California's reservoirs and waterways. The mussels threaten aquatic food chains in lakes, access for fishing and boating, recreation-based economies and the state and federal government's ability to send water to Central Valley farmers and beyond.
Once quagga mussels arrive in a water system, they float downstream, where lakes in their paths can topple like a string of dominoes. Since being found in Lake Mead in 2007, they have drifted downstream and been verified in 16 lakes and rivers on the Colorado River chain. In addition, zebra mussels, a slightly smaller infester, were found in January at San Justo Reservoir near Hollister (San Benito County).
The reaction by the Department of Water Resources, Department of Fish and Game and local water agencies has been swift and severe.
San Justo was immediately closed to all boating. In Southern California, Lake Casitas, where anglers have caught some of the largest bass in history, was also closed to outside boats, as was smaller Westlake. This was a defensive measure. No mussels were found in either lake.In Northern California, the East Bay Municipal Utility District considered closing three of its most popular fishing lakes - San Pablo Reservoir near El Sobrante, and Pardee and Camanche in the San Joaquin foothills. EBMUD opted instead for rigorous checks for all trailered boats and to ban boats from Santa Clara County, San Benito County and Southern California.
"We can hold quagga mussels at bay, we can draw that line," said Alexia Retallack of the Department of Fish and Game. "Quagga will not move from one watershed to another without human assistance."
The only solution, she said, was for boaters to drain, clean and dry their boats, trailers and equipment.
Once introduced, the results from quagga mussels can be devastating. "Quagga are floaters, so wherever the water goes, they go," Retallack said. "From Lake Mead, for instance, any lake getting raw Colorado River water is exposed. ... The situation compounds."
Series of threats
To aquatic life: Invasive mussels feed by filtering water. In turn, high numbers of mussels remove plankton from a lake, which cleans out the base of the aquatic food chain. Small fish thus have nothing to feed on and have very low survival rates. Large fish then eat what small fish remain until they too run out of food.
When nutrients are removed from a lake, the water clears and sunlight reaches the bottom. That encourages weed growth. When the weeds decay, they soak up oxygen. That is why large weed die-offs in lakes cause massive fish kills through oxygen deprivation.
Quagga mussels also produce high collective amounts of pollutants in their waste. "Back east, quagga have caused outbursts of botulism that have caused the deaths of birds," Retallack said. "They can actually change the pH of a lake, making it more acidic, so it smells."
To recreational boating: Water districts could close major recreation lakes to boaters, as has been done at Casitas, the great bass lake. This would damage lake-based local economies and the boating industry, as well as recreational opportunity for the roughly 1 million California boaters. In the Great Lakes region, one study showed the quagga mussel cost the economy $5.1 billion over seven years.
At lakes where quagga mussels are present, such as Lake Mead, a study found 50 percent more overheated engines, sloppy steering and an increased drag. That is because the mussels adhere to surfaces both inside the engine and the hull of the boat.
While these scenarios may exist at infested lakes, that does not mean it will be the fate of Northern California waters, Retallack said.
"We've been looking at Minnesota and Wisconsin, where they have quagga," Retallack said. "In Minnesota, they took a hard line approach. They required all boaters to clean, drain dry their boats. They educated the public. They have almost eliminated their new infestations, this in 'The Land of 10,000 Lakes.' They stopped the quagga from moving.
"But Wisconsin did not take a hard stand and Wisconsin has rampant infestation. It demonstrates the difference between letting the public know how they transport quagga and how they can stop it, and doing little to nothing."
The jury is still out on the public's ability to do the right thing in California. Since January, 83,000 trailered boats have gone through check stations, mostly in Southern California for boats returning from the Colorado River and its lakes, and 104 have been verified with quagga.
To pipelines: One quagga mussel can produce 40,000 eggs in a single spawning and up to a million eggs in a year, Retallack said. "I have a pipe that was suspended in Lake Mead for one and a half months," she continued. "The pipe is 9 inches long, 31/2 inches in diameter. It has small mussels all over the outside and is completely coated on the inside. Not only do you have this first layer, but you also have a second layer where quagga mussels were starting to settle on top of the other mussels."
So what you get are layer upon layer of mussels until they choke off pipes, or any other surface they attach to. In irrigation systems, they can clog pipes from the intake to the sprinkler heads, a bleak scenario for the agricultural industry.
In the Eastern U.S., dual pumping systems are in place in some areas. When one is clogged with quagga mussels, it will be shut down and cleaned out. By the time it is clear, the other system will be clogged. "Can you imagine if California had to install parallel water systems?" Retallack asked.
For this spring, a widespread boaters' information program is being established across the state.
At San Justo, where zebra mussels were verified, all boating was stopped and water officials are trying to trace the origin of the introduction. If the mussel arrived via a canal, the source reservoir must be located and locked down, the DFG said. If it arrived via boat, the hope is that it can be treated locally. Mussels in San Justo could threaten water deliveries to local farmers this summer.
At Lake Mead, the source of the quagga mussel for California, the National Park Service is requiring decontamination when boats when pull out at the ramps. At San Pablo, Camanche, Pardee and many others, a thorough check that takes about 10 minutes is required before boats are allowed to launch.
At Clear Lake, the largest freshwater lake inside the state's borders, authorities will require all boats entering the county to undergo a mandatory inspection. Santa Barbara County supervisors voted last Tuesday to require a similar inspection for Lake Cachuma, one of the best bass lakes in California, rather than close the lake.
"We don't want to see people lose recreation opportunity," Retallack said. "To stop quagga, boating and water recreationists must clean, drain and dry all of their equipment. That includes boats, trailers, kayaks, canoes, scuba gear, anything that gets in the lake."
With spring boating season imminent, that is the only answer.
End Quote.
Doug
