Environmentalists remove aquatic weeds from Emerald Bay | TahoeDailyTribune.com

Environmentalists remove aquatic weeds from Emerald Bay

Matthew Renda

SOUTH LAKE TAHOE, Calif. – Environmentalists are declaring victory after a population-growth control technique successfully eradicated most, if not all, remnants of an invasive aquatic plant from part of the floor of Emerald Bay near Swim Beach.

Using a similar technique to kill invasive Asian clams, a partnership of local environmental agencies installed large swathes of bottom barriers to curtail the growth of Eurasian watermilfoil in Lake Tahoe.

In June, a partnership including Tahoe Resource Conservation District, California Department of Parks and Recreation and the Tahoe Regional Planning Agency placed more than 8,500 square feet of bottom barriers, according to Kim Boyd, Invasive Species manager at the conservation district.

Project coordinators supplemented the barriers with divers who removed the weeds outside of the barriers’ range by hand

On Sept. 14, four divers along with other workers removed the bottom barriers to reveal sand, with no signs of invasive weeds where the barriers had been placed, according to Boyd.

The operation to remove the barriers was relatively seamless, Boyd said. Early on there were worries that the barriers would be difficult to remove due to water pressure and accumulation of sediment on top of the implements.

“We had four divers who removed the barriers and then handed them to workers on shore who dragged them from the water,” she said. “It went very quickly.”

Boyd further said the project successfully achieved the objective of removing “a significant portion of one known, discreet infestation site.”

“We’re very optimistic about the initial results of this pilot project because it demonstrates that it is possible to eradicate the majority of an infestation in a specific locale,” said California Department of Parks and Recreation Environmental Scientist Dan Shaw. “These findings will help us establish a control plan for aquatic invasive weed populations in Emerald Bay and other afflicted areas of Lake Tahoe.”

The agencies will continue to monitor the site near Swim Beach to ensure the weeds do not return, Boyd said.

Future control efforts will require more limited maintenance removal to keep the beach and pier free of aquatic invasive weeds, greatly reducing control costs, according to Peter Brumis, Public Outreach Specialist with the resource conservation district.

Due to the success of the operation, there are plans to treat other sites in Emerald Bay and other portions of Lake Tahoe where Eurasian watermilfoil is present, Boyd said.

“Our goal is to get the population of invasive plants in Tahoe back to a manageable size,” she said.

The project was funded by two separate grants – one in 2006 and one in 2008 – provided by the Bureau of Reclamation, a water management agency that concentrates on water issues in the American West.

Further funding for similar projects to be instituted next year will come from the Southern Nevada Public Land Management Act.

The advent of bottom barriers began in 2005 with much smaller 10-foot-by-10-foot swaths of material, Boyd said. The difference between then and now, is the bottom barrier cover a much larger area – 8 foot by 40 foot – meaning population control is more effective, Boyd said.

The weed-killing technique has been and will continue to be used to control curly-leaf pondweed, another rapidly spreading aquatic invasive plant found in Lake Tahoe.

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