South Lake Tahoe, CA — The Tahoe Regional Planning Agency (TRPA) will host a public hearing January 26 to decide on the next steps for the Tahoe Keys aquatic weeds test project, the agency said today. The test project received votes of support from the Lahontan Regional Water Control Board and TRPA Advisory Planning Commission earlier this month.

This project proposed by the Tahoe Keys Property Owners Association (TKPOA) will analyze which combination of treatment methods best protect Lake Tahoe by most effectively controlling aquatic weeds in the Tahoe Keys lagoons and halting their spread into the lake.

TRPA, as co-lead agency with the Lahontan Water Board, will consider certification of the Final Environmental Impact Statement (EIS), which evaluates the potential environmental impacts of the proposed control methods test and project alternatives, and approval of a permit to begin the tests.

“The aquatic invasive weeds have continued to spread, despite our investments of millions of dollars to contain and remove the plants,” said Greg Hoover, Water Quality Manager for the Tahoe Keys Property Owners Association. “Recent collaborative efforts to slow the spread into Lake Tahoe have shown some promise, but new control methods such as aquatic herbicides shown to be safe and successful in similar settings need to be tested to help prevent widespread infestations around the lake.”

The aquatic weed infestation covers over 90 percent of the Tahoe Keys lagoons in the summer and provides sources of continuing infestations in the lake itself including popular recreation areas like Emerald Bay. The invasive weed growth degrades water quality and clarity, disrupts the natural ecosystem, impedes boating and recreation and releases nutrients that can contribute to harmful algal blooms. Despite considerable investment by property owners, the weeds continue to spread and officials and the scientific community are urging immediate action.

The proposed test project will weigh myriad approaches:

  • Testing EPA-certified aquatic herbicides
  • Innovative methods such as aeration and ultraviolet light. Lake Tahoe was the first location to use ultraviolet light to treat aquatic weeds, but it has only been used on a small scale.
  • Small-scale control methods (such as bottom barriers and diver-assisted suction)

Aquatic weeds affect multiple areas around Lake Tahoe. The Tahoe Keys lagoons encompass over 170 acres (including 900 private docks) and the largest commercial marina on Lake Tahoe supporting private, public recreational, and commercial launching and boating, and therefore accounts for much of Lake Tahoe’s boat traffic.  Due to the sheer size of the infestation and the number of boats leaving the area, the Tahoe Keys are a likely source for new infestations around the lake.

“This is not a TKPOA problem, this is a lake-wide issue,” said Tahoe Regional Planning Agency Executive Director Joanne S. Marchetta. “We’ve seen public and private partners come together to improve and fund elements of this environmental process because everyone understands that we are at a tipping point. The results of this decision will influence the future of Lake Tahoe for years to come.”

The TRPA public hearing will provide an overview of the proposed project, project alternatives, and the analysis of potential environmental impacts. Thousands of public comments have been included in the final analysis and additional opportunity for input will be provided during the virtual meeting.

TRPA Governing Board Meeting
January 26, 2022
Materials will be available on Wednesday, January 19 here.

The TRPA Advisory Planning Commission voted to recommend the Governing Board certify the final Environmental Impact Statement for the test project at its January 18, 2022 meeting. Meeting materials are available here.

The Lahontan Water Board voted unanimously to  issue a National Pollutant Discharge Elimination System Permit and certify the Environmental Impact Statement during their January 12-13, 2022 meeting. You can visit the Lahontan Water Board website at: Lake Tahoe Programs | Lahontan Regional Water Quality Control Board (

Learn more about the project at


[This story was updated January 17 to include the Advisory Planning Commission meeting link and to announce the Lahontan Water Board decision from January 13.]

[This story was updated January 18 to include the Advisory Planning Commission vote to recommend the Governing Board certify the final environmental impact statement for the test project.]

The Tahoe Regional Planning Agency leads the cooperative effort to preserve, restore, and enhance the unique natural and human environment of the Lake Tahoe Region, while improving local communities, and people’s interactions with our irreplaceable environment. For additional information, contact Jeff Cowen, Public Information Officer, at (775) 589-5278.