Lake Tahoe clarity program shields lake from record amount of runoff
Cornerstone Lake Tahoe clarity program shields iconic lake from record amount of runoff
California & Nevada efforts keep nearly 737,000 pounds of pollutants out of the lake while scientists continue to expand clarity research
Lake Tahoe, CA/NV – Protecting Lake Tahoe’s iconic water quality, a joint California-Nevada effort, prevented a record quantity of fine-grained sediment and other pollutants from reaching the lake’s dazzling blue waters in 2025, according to an annual performance report released today.
By restoring wetlands and streams, limiting dust from roads and construction sites, and improving stormwater systems and other anti-pollution actions, partners in the Lake Tahoe Total Maximum Daily Load Program (TMDL program) kept an estimated 736,600 pounds of sediment known to harm clarity and water quality out of the lake.
The performance report by the Lahontan Regional Water Quality Control Board, which is part of the California Environmental Protection Agency, and the Nevada Division of Environmental Protection found that an estimated 5,875 pounds of nitrogen and nearly 2,120 pounds of phosphorus were prevented from reaching the lake in 2025, all annual record highs since the program began tracking these statistics in 2016.
“Lake Tahoe is an ecological treasure we are committed to protecting now and for future generations,” said Yana Garcia, California Secretary for Environmental Protection. “As we continue to enjoy this special place, we applaud our statewide and interstate partnerships. Without countless regional partners, and our colleagues in Nevada, the lake’s extraordinary water quality this summer and in recent years would not be possible.”
"Protecting Lake Tahoe requires long-term commitment, strong partnerships, and continued adaptation as new challenges emerge," said Jennifer Carr, administrator of the Nevada Division of Environmental Protection. "The progress highlighted in this report reflects years of collaboration among agencies and local partners on both sides of the state line. As our understanding of the factors affecting Lake Tahoe's clarity continues to grow, Nevada will continue advancing the science behind the TMDL program to ensure our strategies evolve alongside the challenges facing the lake."
Launched in 2011, the TMDL program is a bi-state effort between California and Nevada to restore and enhance the lake’s water clarity to historic levels by requiring local governments and highway departments on both sides of the lake to implement measures that help prevent clarity-harming pollutants from reaching the lake. The TMDL program incentivizes urban implementation partners to use customized strategies for holistic pollution reduction rather than having to take a one-size-fits-all approach, and it awards credits to urban implementers once pollutant control effectiveness is verified.
Last year, highway departments and local governments on both sides of the lake exceeded their targeted pollutant load reductions.
In time, the TMDL program’s main goal is for people to once again be able to see to depths of 100 feet in Lake Tahoe. The lake’s annual average clarity in 2025 was 69.2 feet deep, seven feet clearer than 2024’s average. However, long-term data show that the lake’s clarity has effectively plateaued despite the continued implementation of the program.
Multiple efforts are underway to better understand the watershed’s evolving dynamics and improve the TMDL program. Researchers are studying how wildfires, plankton and invasive species – drivers of clarity that were not fully foreseen when the program was created – are contributing to the lake’s ongoing clarity trend.
"Lake Tahoe’s clarity is stabilizing, but with new pressures like wildfires and a rapidly changing climate, we must keep refining our approach,” said Ben Letton, Lahontan Water Board executive officer. “We are advancing the science behind the TMDL program to better understand these pressures and will adjust it where needed to protect the lake’s long-term health.”