LAKE TAHOE, Nev./Calif.  — Today, the UC Davis Tahoe Environmental Research Center and Tahoe Regional Planning Agency released findings from the 2025 Lake Tahoe Clarity Report, which showed annual average clarity — or how deep a 10″ white disk can be lowered into Lake Tahoe before it becomes invisible from the surface — was statistically unchanged compared to the year prior. This continues a trend since the late 1990s of relatively stable, but not improving, Lake clarity. 

After decades of steady water clarity loss in the latter half of the 20th century, organized efforts by Keep Tahoe Blue and other partners in Tahoe’s Environmental Improvement Program (EIP) helped stabilize Lake Tahoe’s world-famous water clarity. EIP projects to restore damaged ecosystems — especially in the Upper Truckee River watershed, Tahoe’s largest tributary — have been effective investments. As have policies to limit urban runoff and improvements to stormwater treatment infrastructure.  

However, more understanding and action are needed to restore water clarity to historic levels. 

“Clarity matters because the water is our biggest clue about how the Lake is doing. If we lose the clear water of Tahoe, we lose everything we love about it,” said Dr. Darcie Goodman Collins, CEO, Keep Tahoe Blue.

“Encouragingly, Lake Tahoe’s multi-year averages for water clarity are stable for another year, despite the continuing trend of declining summer clarity readings.

We know that fine sediment particles cloud Tahoe’s waters. Over the past two-plus decades, investments in programs to limit these particles — from roads, urban areas, and degraded streams and wetlands — have been successful. The UC Davis report reinforces that those ecosystem restoration and stormwater treatment efforts have been good for water clarity. Yet, the data once again shows that stopping fine sediment pollution is not enough to bring back the water clarity lost last century.

Science is key to protecting and restoring Tahoe’s water clarity, just as it has been for seven decades. The scientific questions we must answer have to do with the flow and exchange of nutrients near the shoreline, which is where aquatic invasive species make their impact, as well as the effects of algae and tiny organisms called phytoplankton on Lake clarity. Climate change, and the far-reaching role it plays, also has to come into better focus.

Answering these questions won’t be easy. But the effort, time, and investment are worth it to ensure our Lake continues to stay beautiful and blue for generations to come.”

Goodman Collins added there are ways that residents and visitors can protect Lake Tahoe through simple choices.

• Parking their cars once and enjoying a Car-Free, Care-Free Tahoe by bus, bike, shuttle, e-scooter, or on foot.
• Stopping the spread of invasive species by ensuring kayaks, floaties, and every piece of water gear is Clean, Drained, and Dry before it touches the Lake.
• Refusing to buy single-use plastics that often end up as trash in our environment.
• Volunteering at restoration events that repair Tahoe’s marshes, meadows, and creeks — the Lake’s natural pollution filters.”