The report by the Lahontan Regional Water Quality Control Board found that an estimated 727,000 pounds of fine sediment; more than 5,800 pounds of nitrogen; and nearly 2,100 pounds of phosphorus were prevented from reaching the lake in 2024 — all annual record highs since the program began tracking these statistics in 2016.
These pollutants can fuel algae growth and harm the lake’s clarity.
The Lake Tahoe Total Maximum Daily Load Program, or TMDL Program, a collaboration between California and Nevada that began in 2011, focuses on restoring wetlands and streams; controlling dust from roads and construction sites; and improving stormwater systems. Local governments and highway departments on both sides of the lake implement strategies like street sweeping and stormwater infiltration, tailored to their communities, to reduce pollution at its source.
While Lake Tahoe’s average clarity in 2024 was 62 feet, slightly lower than previous years, experts stress that long-term trends are the best indicator of the lake’s health.
The TMDL Program has steadily reduced sediment, nitrogen, and phosphorus inputs over time, helping to maintain the lake’s water quality despite increasing pressures from climate change, wildfires, and extreme weather.
Scientists and local agencies are also studying additional factors that affect lake clarity, including warming air and water temperatures and invasive species.
