Lake Tahoe, CA/NV — This Halloween, the scary side of Tahoe is not limited to above ground. The introduction of new aquatic invasive species threatens to wreak havoc on Lake Tahoe’s ecosystem and recreational amenities.

Despite hurdles from COVID-19, hazardous air quality and evacuations from the Caldor Fire, Lake Tahoe’s Watercraft Inspection Program had another successful season as there have been no new invasive species detected in the Lake Tahoe Region.

Inspectors intercepted 28 boats with invasive Dreissenid mussels, marking a grim milestone; the most ever found in a single season. Travelling boats and trailers are the most common way aquatic invasive species are spread. This substantial increase in intercepted mussels stems from a large number of newly purchased boats from other states with known aquatic invasive species and a general increase in boating activity and travel. In comparison, inspectors intercepted 20 mussels in 2020 and nearly half that the year prior.

If Dreissenid mussel species including zebra and quagga mussels along with other aquatic invasive species like New Zealand mudsnails were to make their way into Lake Tahoe, they could wreak havoc on the lake’s fragile ecosystem, clarity, regional economy, and quality of recreation in the basin. Watercraft inspectors diligently inspect every watercraft that comes through the stations for all types of aquatic invasive species.

While the amount of mussels found is astonishing, the number of boats going through inspection stations is also increasing. “With an uptick in the volume of boats, higher numbers of infested boats is expected,” said Thomas Boos, who directs the program for the Tahoe Regional Planning Agency. “The program is one of the best in the nation because we are so thorough, but it’s startling to see this shift. Boaters really need to be helping us.”

The best way to stop the spread of aquatic invasive species is to Clean, Drain and Dry watercraft before entering another body of water.  Every boat found with any vegetation, water, mud or animals will receive a decontamination before launching into the lake. Even as the boating season slows down, it is imperative to continue these practices year-round for both motorized and non-motorized watercraft.

The summer of 2021 was the first season the highly successful appointment system was fully implemented for inspections. Boaters took full advantage of scheduled appointments and shorter wait times. The appointment schedule for the next season will open in spring 2022.

At the beginning of the month, watercraft inspection stations transitioned to their winter locations at Cave Rock on the East shore and the Lake Forest boat ramp in Tahoe City. The lake’s low water levels are not expected to affect either of these year-round launch sites. Both boat ramps will be open daily (weather permitting) for inspections from 6 a.m. to 4 p.m. Inspections will be first-come, first-served. Decontaminations need to be scheduled several days ahead of time. Watercraft arriving Clean, Drained and Dry typically get on the water immediately.

Keep up with the latest information and weather closures by following the Lake Tahoe Watercraft Inspection Program on social media through Facebook, Twitter and Instagram (@TahoeBoating) or online at You can find useful information on aquatic invasive species and tips on how to prepare for watercraft inspections.


The Lake Tahoe Aquatic Invasive Species Program is implemented by 40 public and private partner organizations, including federal, state, and local jurisdictions, research partners, public utility districts, and private marinas. The Tahoe Regional Planning Agency and the Tahoe Resource Conservation District lead the program in collaboration with the public and private partners. The program’s mission is to prevent, detect, and control aquatic invasive species in the region so that future generations can enjoy Lake Tahoe. For additional information, contact Jeff Cowen, Tahoe Regional Planning Agency Public Information Officer, via email or at 775-589-5278.