CA-NV report highlights efforts to improve Lake Tahoe’s clarity

Bi-state efforts to reduce pollution and restore Lake Tahoe’s world-famous water clarity remain on track, according to an annual lake performance report released today by the Nevada Division of Environmental Protection (NDEP) and the Lahontan Regional Water Quality Control Board, part of the California Environmental Protection Agency (CalEPA).

The report outlines the program’s progress and highlights the commitment of Total Maximum Daily Load (TMDL) Program partners to help restore Lake Tahoe’s water clarity. The report found that the amount of light-scattering fine sediment that made it into the lake was reduced by 303 tons in 2022, or about the weight of a Boeing 747 jet. Nitrogen and phosphorus pollution, which contributes to algae growth, also was reduced by thousands of pounds per year, thanks to collaboration between Nevada and California; support from federal, state and local agencies; and help from private landowners in the Tahoe Basin.

The annual report is part of the bi-state Lake Tahoe TMDL Program. Launched in 2011, the program seeks to restore clarity to a depth of at least 78 feet by the end of 2031. This interim goal is referred to as the Clarity Challenge. In time, the goal is for people to once again be able to see to depths of 97 feet.

While past years have seen some declines in Lake Tahoe’s water clarity, the TMDL Program has helped stabilize these levels. In 2022, Lake Tahoe’s water clarity was measured at a depth of 72 feet – almost 11 feet deeper than the 2021 recording. The Nevada Division of Environmental Protection and the Lahontan Water Board are hopeful that this measurement is a sign that water clarity at the lake will continue to improve and bring the program closer to meeting the Clarity Challenge.

“The progress made toward restoring Lake Tahoe clarity has been and continues to be encouraging,” said Jennifer Carr, Administrator of the Nevada Division of Environmental Protection. “These results could not have been achieved without sizable resource commitments and the hard work of our implementing partners and residents. I commend all who have been involved in helping to protect this extraordinary treasure.”

The report noted that significant progress was made by forest management agencies in 2022 to control and prevent pollution impacts from activities to suppress the Caldor Fire. In 2021, the Caldor Fire burned more than 10,000 acres within the Upper Truckee River and Trout Creek watersheds, necessitating over 300 acres of new disturbed area to be created to control spread of the fire.

“I’m pleased to join so many Californians in celebrating this latest report showing the improvement in clarity of Tahoe’s precious water this year. It’s important to know that it took significant work and collaborative partnership to get us here,” said CalEPA Secretary Yana Garcia. “For over a decade the Lahontan Water Board has worked tirelessly with the state of Nevada to implement water quality standards that help preserve, enhance, and stabilize water quality in the lake – a challenging task in light of several climate change-driven factors including the impacts of wildfires like the Caldor Fire. While we celebrate this improvement today, we know we still have much to do to protect this invaluable shared resource and more like it.”

Some key findings from the 2023 Performance Report include:

• Urban partners continue to meet load reduction targets by installing and maintaining innovative controls to reduce polluted stormwater runoff that makes its way to the lake.
• In 2022, significant efforts occurred to remediate fire management activities, such as firebreaks, put in place during the 2021 Caldor Fire to control fire spread.
• Collective implementation actions have helped water clarity stabilize. While lake clarity improved in 2022 to a depth of 72 feet, this value is within the range of what has been observed over the last several decades. Future measurements will give researchers a better idea of whether this improvement represents a positive trend.
• NDEP and the Lahontan Water Board continue to work with partners on program implementation, including coordinating with the scientific community, to assess progress toward achieving established goals. This includes researching how climate change and alterations in lake ecology influence clarity conditions.

To learn more about the TMDL Program and accomplishments to improve Lake Tahoe’s water clarity, view the Lake Clarity Tracker.