Last summer marked the completion of the Tahoe Keys Lagoons Aquatic Weed Control Methods Test (CMT) — a three-year, science-based testing program aimed at tackling Lake Tahoe’s largest and most persistent infestation of aquatic invasive weeds. For decades, invasive weeds in the Tahoe Keys lagoons have been spreading into the greater lake, risking water quality, recreational access, and the native ecosystem.
The test was complex: it trialed every available tool — including ultraviolet light technology and the one-time application of EPA-certified herbicides — to fight aquatic invasive weeds. Now, as agency experts and independent scientists analyze the 500,000 data points collected during the test to determine effective and sustainable treatment, containment of invasive weed fragments is the top priority.
While long-term solutions are developed, fragments from fast-growing weeds like Eurasian watermilfoil and curlyleaf pondweed continue to break off and float toward the lake. Their ability to regrow from small fragments makes them a critical threat. Small infestations detected around Lake Tahoe have been quickly stamped out by divers when they are caught early.
In response, the Tahoe Keys Property Owners Association (TKPOA) and League to Save Lake Tahoe, working with the Tahoe Keys Marina and Tahoe Regional Planning Agency (TRPA), developed a robust, multi-layered containment plan to manage the spread of weeds in four critical areas: the homeowners’ lagoons, Tahoe Keys Marina, and the two boating channels that connect the lagoons to the lake.
Current weed fragment containment strategies include bubble curtains, fragment catch devices, dedicated boats and staff to skim fragments, Boat Back-Up Stations, and public education to increase awareness and vigilance.
Bubble curtains stretch across the channels, creating a continuous wall of tiny bubbles that trap weed fragments inside the lagoons. While bubble curtains have been around for decades, using them for aquatic weed containment was pioneered by the League to Save Lake Tahoe and TKPOA in 2018. The bubble curtain is the only physical barrier to prevent fragments from crossing through the boating channel, while still allowing boats to pass. The League is investing in bubble curtain improvements and ongoing efficacy studies for this technology.
At the Boat Back-Up Stations, boaters are required to stop in marked areas inside the bubble curtains and reverse their propellers to dislodge any tangled weed fragments. TKPOA skimming crews are on-site five days a week to monitor activity and collect debris.
Containment efforts extend beyond the channels, too. At the 15th Street Lagoon, new screening systems help prevent fragments from entering the sensitive marsh area. Homeowners are playing a part as well, with many installing bottom barriers near their docks and vessels to reduce fragment release. Additional strategies, such as ultraviolet light treatment, scuba diver-assisted removal, autonomous skimming robots, and filtration systems will reduce the overall mass of weeds — both curlyleaf pondweed and Eurasian watermilfoil — helping to make containment more effective.
Non-motorized boaters can do their part to contain weeds and other invasive species by following Clean, Drain, Dry protocols for all water equipment including kayaks, paddleboards, inflatables, fishing gear, and accessories, before they move from one area to another. A CD3 machine — short for Clean, Drain, Dry, and Dispose — is stationed at, and provided by, the Tahoe Keys Marina. It’s a free, solar-powered machine on wheels with on-board tools like compressed air, a vacuum, and brushes, making it easy to do your part to protect Lake Tahoe, Fallen Leaf, and Echo lakes.
These combined efforts are a critical buffer this summer. While they won’t solve the problem of invasive weeds on their own, they can keep it from getting worse while agencies work toward long-term solutions.
Protecting Lake Tahoe’s pristine waters depends on collaboration. While scientists and experts analyze findings from the Tahoe Keys Lagoons Aquatic Weed Control Methods Test, containment efforts are critical to make sure we don’t lose progress. Continued partnership and focus on containment will help protect the waters of the Tahoe region from the spread of harmful aquatic weeds.
