Lake Tahoe watercraft inspectors stopped two boats this month that were headed for the lake carrying highly invasive golden mussels. The interceptions are both a reminder of the threats Tahoe faces and a testament to the resolve of the people working to protect it.

Tahoe Regional Planning Agency (TRPA) and Tahoe Resource Conservation District watercraft inspectors spotted the invasive mollusks and quickly flagged the boats for decontamination and further inspection. There have now been three golden mussel detections at Lake Tahoe since they were discovered for the first time in North America just a few hours away.

Golden mussels have been called “invasive species on steroids.” Their survivability and reproduction rates are extraordinary, even compared to quagga and zebra mussels, which our watercraft inspection program has kept out of Tahoe for nearly 20 years. A mussel infestation could devastate the lake’s ecosystem and the shoreline areas where residents and visitors gather to swim, paddle, and simply enjoy the beach. 

The program worked exactly as it was designed to. Mandatory inspections of thousands of motorized watercraft every year lower the risk of a new aquatic invasive species polluting our waters. The partnership of agencies, marinas, inspectors, public land managers, and boaters who keep their equipment Clean, Drained, and Dry have made the Lake Tahoe Watercraft Inspection Program a national model for invasive species prevention.

Vigilance is growing with non-motorized recreators, too. More than 8,000 residents and visitors have become Tahoe Keepers, trained in how to Clean, Drain, and Dry their gear. It’s essential that we clean all paddleboards, kayaks, fishing equipment, and beach toys. Solar-powered CD3 (Clean, Drain, Dry, Dispose) stations are located at popular beaches and river access points. Roving inspectors and Lake Tahoe ambassadors educate thousands of people headed for the water—look for them this summer. 

At its core, the Watercraft Inspection Program is about keeping Lake Tahoe clean and clear for everyone today and for future generations. This vision is what has driven Lake Tahoe’s conservation for decades. In the 1960s, scientists with UC Davis Tahoe Environmental Research Center began documenting a troubling decline in lake clarity. Unmanaged development had damaged or destroyed most of the wetlands vital to helping filter Tahoe’s crystal-clear waters, and pollutants were flowing freely into the lake. The creation of TRPA in 1969 by Nevada and California helped enact policies to protect sensitive wetlands, set growth limits, and required water quality improvements with every new project. According to the development plans of the day, the bi-state partnership prevented a city rivaling the size of San Francisco from being built at Lake Tahoe. 

But protection alone wasn’t enough. It wasn’t until TRPA paired land-use protections with active restoration through the Lake Tahoe Environmental Improvement Program (EIP) in the late 1990s that clarity began leveling off. The UC Davis Tahoe Environmental Research Center has continued reporting on clarity, and over the last 20 years, clarity has stabilized. The recently released 2025 clarity report showed that the lake’s average clarity improved by about 7 feet—the annual average in 2025 was 69.2 feet and 62.3 feet in 2024. That 7-foot improvement is a good short-term gain, but not statistically different from recent years, mostly due to a continuing trend of relatively low clarity during summer.

Stability is meaningful. It reflects decades of growth management, environmental requirements, and major EIP investments in wetland restoration and stormwater improvements. But stability is not the finish line. The goal has always been to restore clarity to its past depth of 100 feet, which requires a deeper understanding of the forces driving lake clarity. The report raises important questions about why trends for summer and winter clarity continue to drift apart.

TRPA is working with the Tahoe Science Advisory Council to find answers. Changes in the lake’s ecology, warming temperatures, changing weather patterns, and the impacts of aquatic invasive species introduced before the watercraft inspection and Tahoe Keepers programs began are among the factors coming under study. Science guided the first phase of interventions—and deepening our understanding of the lake’s complexity must remain central to how we manage the Tahoe Region going forward.

The lake we are all working to protect is irreplaceable. And the community behind it—researchers, boaters, watercraft inspectors, Tahoe Keepers, and EIP partners—gives us every reason to push onward with optimism. 

-Julie Regan

Julie W. Regan is Executive Director of the Tahoe Regional Planning Agency.