Progress made against invasive species
August 24, 2007
Officials are preparing several lines of defense in the battle against invasive species in Lake Tahoe, but they remain uncertain whether an effective plan of action can be implemented before it’s too late.
Local divers are receiving training on how to remove aquatic weeds by hand. A boat has been outfitted with suction equipment to vacuum up beds of unwanted plants. Pilot monitoring and removal projects are under way. A watercraft inspection program and portable boat-washing station are in the works.
And the subject has captured the public’s attention, officials say.
Phil Brozek, the Army Corps of Engineers program manager for Lake Tahoe, said he is optimistic about the level of funding and attention the threat from invasive aquatic species has received in the past year.
But it’s too early to be optimistic about Lake Tahoe’s future with regards to the invaders, Brozek said.
“I don’t think anyone can say until they get more information,” Brozek said in a phone interview. “If mussels are established ” there’s no known cases of eliminating mussels once they’re established.”
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The Army Corps, along with other entities including the Truckee River Foundation, the Tahoe Regional Planning Agency and the Incline Village General Improvement District, committed more than $1 million in funds to the battle in April, Brozek said.
The funds are waiting final approval from project partners, Brozek said. Once the money is available, numerous agencies around the basin will unleash a series of prevention and eradication efforts, including a survey of Lake Tahoe to determine the number and extent of invasive species.
The Army Corps will compile an integrated management plan that takes a comprehensive and analytical look at the basin’s invasive aquatic species. The plan will outline strategies recommended for local agencies, Brozek said.
“This plan doesn’t have the authority to make anybody do anything,” he said.
The Tahoe Resource Conservation District received a $300,000 grant from the federal Bureau of Reclamation last October to conduct pilot removal projects and surveys in Emerald Bay and Ski Run in South Shore, said Jenny Francis, who coordinated the district’s invasive species program for Lake Tahoe.
Working with the Tahoe Regional Planning Agency, the California State Lands Commission and the Lake Tahoe Diver’s Conservancy, the district is testing out a monitoring and removal system for Eurasian water milfoil and curlyleaf pondweed in two manageable sites, Francis said.
They have taken hydroacoustic sonar data to measure the mass of the aquatic weeds, while divers are pulling up milfoil and curlyleaf like gardeners pull dandelions up from a field.
The bistate Tahoe planning agency has begun taking turbidity measurements to test whether those removal procedures affect lake clarity, Francis said. And she added that the resource district’s pilot projects will suggest whether the removal effort can be applied on a larger scale, Francis said.
“We can only get this ball rolling and implement this program as fast as we can,” Francis said. “It’s positive; we’re moving forward, but it’s just one step at a time.”
The Lake Tahoe Diver’s Conservancy is creating a new Aquatic Plants Research Diver Certification to train local divers removal procedures, said Phil Caterino, a chief research diver with the conservancy.
In Tahoe, divers either use suction equipment to assist hand removal, or use a bottom-barrier method that blocks ultraviolet rays, inhibiting photosynthesis and killing the plant, Caterino said.
“What we’re trying to do is put [milfoil] in check,” Caterino said. “It has just exploded over the past year.”
In past years, Idaho-based diver Doug Freeland of Aquatic Consulting and Evaluation conducted bi-annual surveys and assisted hand-removal projects in Emerald Bay and Ski Run. But the weeds need to be removed on a regular basis and on a larger scale, Freeland said.
“Hopefully we’re going to get to the point where there’s local people who can do what I do,” Freeland said. “[Diver-assisted removal] is effective if you stay on it; you can’t just do a day here and a day there.”
SIDEBAR What is Tahoe up against?
Ever since the alarming discovery of quagga mussels in Lake Mead January, the threat posed by aquatic invasive species has moved up the priority list.
Once quagga mussels invade a lake, there is no stopping their invasion, said Rita Whitney, threshold monitoring program manager with the Tahoe Regional Planning Agency. Quagga mussels colonize rapidly in huge numbers. They become a nuisance when their shells clog water pipes and inhibit water intake. Or when the mussels die, and their sharp shells litter the beaches.
“You have to wear shoes,” Whitney said. “You can’t even walk on the beaches.”
Quagga mussels have a ferocious appetite for algae, Whitney said. They eat all the nutrients, disturbing the natural food chain. In the end, lakes infested with quagga mussels are devoid of other life.
Since the Lake Mead discovery, larva for quagga mussels were found in Lake Powell, Whitney said.
And three boats with zebra mussels were intercepted at the Truckee Department of Agriculture this summer, Francis said.
But mussels are not the only aquatic invader to worry about. Eurasian water milfoil and curlyleaf pondweed already run rampant in Emerald Bay and Ski Run, officials said.
“There’s about three-weeks worth of removal there that needs to be done,” Francis said.
Caterino said milfoil is growing throughout the lake and is starting to make it’s way down the Truckee River. The plants are starting to seed, he said.