For decades, the UC Davis Tahoe Environmental Research Center has been tracking the clarity of Lake Tahoe with a white disc known as a Secchi disk, lowered into the depths of “Big Blue.” For nearly 60 years, their findings have been released annually in the Lake Tahoe Clarity Report. The most recent report, which contains the data from 2025, was released on Tuesday. The 2025 report shows that the annual average clarity remains at a plateau, neither significantly improving nor declining compared to previous years. The annual average was 69.2 feet in 2025. That is 7 feet clearer than last year’s average of 62.3 feet, but not statistically different from recent years, mostly due to a continuing trend of relatively low clarity during summer.

Other Lake Tahoe news:

• KOLO (Reno, Nev.): Lake Tahoe clarity holding steady, report shows
• Active NorCal (Redding, Calif.): Lake Tahoe’s water clarity is holding steady but still far from where it used to be
• UC Davis: Blog: 2025 Lake Tahoe clarity report released