Partners in the Lake Tahoe Total Maximum Daily Load Program (TMDL Program) have reduced fine sediment entering Lake Tahoe by 29% since 2004, along with a 23% reduction in nitrogen and a 17% decrease in phosphorus. These efforts are aimed at addressing pollutants that contribute to algae growth and diminish the lake's clarity.
A recent report from the Lahontan Regional Water Quality Control Board and the Nevada Division of Environmental Protection (NDEP) highlighted that in 2024, an estimated 727,000 pounds of fine sediment, over 5,800 pounds of nitrogen, and nearly 2,100 pounds of phosphorus were kept out of Lake Tahoe. These figures represent annual record highs since data collection began in 2016.
“Through long-term investments in science, we’ve been able to protect one of our most treasured natural landmarks,” said Yana Garcia, California Secretary for Environmental Protection. “California is helping to stop hundreds of thousands of pounds of harmful runoff from entering Lake Tahoe each year with successful local and regional partnerships, and strong collaboration with the state of Nevada. As climate challenges grow, we remain firmly committed to restoring the lake’s clarity and strengthening its resilience for years to come.”
The bi-state report noted that all urban implementing partners—including state transportation departments and several counties—exceeded their targets for reducing pollutants. These reductions are calculated using the Pollutant Load Reduction Model; actual numbers may vary.
“Protecting Lake Tahoe’s iconic clarity requires long-term commitment, collaboration and innovation,” said Jason Kuchnicki, chief of NDEP’s Bureau of Water Quality Planning. “These results reflect the strength of the bi-state partnership and the dedication of local agencies implementing proven, science-based strategies to reduce pollution at its source. As we continue adapting to new challenges, this program remains a cornerstone of our efforts to safeguard one of Nevada’s—and the nation’s—most treasured natural resources.”
The TMDL Program began in 2011 as a cooperative initiative between California and Nevada. It aims to restore water clarity by requiring local governments and highway departments around Lake Tahoe to implement measures preventing pollutants from reaching the lake. The program awards credits based on pollution reduction performance while allowing customized approaches rather than standard solutions.
Measures such as street sweeping and stormwater infiltration are intended to help reach a goal of at least 78 feet visibility by 2031. Ultimately, officials hope visibility will return to depths near 100 feet.
Despite these pollution reductions in 2024, average annual water clarity was measured at only 62 feet—lower than readings from previous years. However, experts say long-term trends are more important indicators than single-year changes; recent data suggest no clear trend toward improvement or decline.
“The 2024 results show that our strategies are working, even as conditions in and around the lake become more unpredictable because of increasing pressures from climate extremes, wildfire and ecological change,” said Ben Letton, Lahontan Water Board executive officer. “Building resilience into our pollutant control efforts is essential.”
Researchers are also working with groups like the Tahoe Science Advisory Council to better understand other factors affecting lake clarity—including wildfires, rising temperatures, extreme weather events, and invasive species—with findings expected later this year.
For more information about ongoing initiatives or access to detailed reports on program performance for 2025, visit the Lake Clarity Tracker – Program Management page.