Conditions right to start aquatic weeds control in Tahoe Keys

Staff Report
The fight to control non-native pondweed and Eurasian milfoil threatening the marsh ecosystem at Tahoe Keys continues.
Tribune file

SOUTH LAKE TAHOE — Environmental factors are favorable for the scheduled start of a control methods test in the Tahoe Keys lagoons, project leaders confirmed last week. Boating, fishing and other water activity restrictions in the test areas began May 9 with herbicide application beginning May 23.

The test will allow scientists to gather new data points and information this spring and summer in the long-waged battle against aquatic invasive weeds in Lake Tahoe. The results will help determine long-term solutions for the lagoons and Lake Tahoe.

Turbidity curtains to isolate the test areas in the Lake Tallac control area were installed early May as were curtains in West Lagoon. Environmental factors that need to be met for the start of the test include sufficient lake level, water temperatures for plant growth and inflow into the lagoons from the lake.

Current projections based on existing snowpack, historical runoff records and the weather outlook suggest water should be flowing into the lagoons through May 2022. Current snowpack data indicates a high probability of “inflow” into the Tahoe Keys from Lake Tahoe at the beginning of the May 23 test window. The test areas will be clearly defined in the waterways with prominent signage and turbidity curtains.

The control methods test, which was unanimously passed by the Lahontan Regional Water Quality Control Board and the Tahoe Regional Planning Agency Board, will use stand-alone and combined use of various control method approaches including targeted herbicides and UV-C light to reduce and “knock down” the abundant growth of invasive and nuisance aquatic weeds in the Tahoe Keys west lagoon and Lake Tallac areas.

The Tahoe Keys Property Owners Association Board of Director’s emergency rule restricting boat and water activities in the treatment areas will be in effect through as late as mid-July 2022. These restrictions include no outside visitor access nor water activities of any kind including swimmers, pets, boats, sailboats, personal watercraft or stand-up paddleboards. The herbicide concentrations to treat the weeds will be at levels safe to humans, pets and fish and wildlife, but avoidance is necessary to protect the validity of the test.

To help homeowners in the treatment areas during the test period the TKPOA board made several accommodations. Boats and other watercraft already docked in the treatment areas prior to May 9 may remain moored but can’t operate during the test period. Water access for homeowner kayaks, stand-up paddleboards and similar watercraft will be allowed at the TKPOA ramps in non-restricted areas on Christie Drive, Wedeln Court, Traverse Court and Slalom Court.

TKPOA also waived regulations against street and driveway parking for boat and trailer storage during the test period. Homeowners will have 10 days from the end of the test to relocate any boats and trailers from the streets. The TKPOA is also gathering a list of homeowners with docks outside the test areas who are willing to offer dock or mooring space to affected homeowners’ boats.

Since the 1980s, TKPOA has invested millions of dollars to combat AIS and worked with prominent regulatory bodies, the Tahoe Regional Planning Agency and the League to Save Lake Tahoe on numerous concepts, including weed harvesting, weed fragment collection, bottom barriers, bubble curtains, aeration and supported research on other new methods. The agencies have mobilized their staffs in support and matched the TKPOA investment.

For more information on the project visit


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