How full is Lake Tahoe?

LAKE TAHOE, Calif. - The Sierra Nevada has seen epic amounts of snowfall this winter and recent measurements at both Phillips and Mt. Rose show water content of the snowpack well above normal.

Mountains around the Lake Tahoe Basin are currently holding 168 percent of the median amount of water. On March 1, 2019, the 16 measuring stations around the lake recorded a low of 36" of snow (176 percent of the median) at the Upper Truckee River to a high of 211" at Lake Lucille (178 percent of the median). When the snow melts, or it rains as it has been over the last couple of weeks, the lake gets more runoff that perhaps it can legally hold.

As of Wednesday, March 6, 2019, the gauge height of Lake Tahoe at Tahoe City is at 6,228.10 feet above sea level. The legal limit of the lake is 6229.10 feet and the natural rim rests at 6,223 feet.

While the lake is only about one foot from the legal limit, the Federal Water Master office in Reno keeps a close eye on the situation.

They can start spilling water from Lake Tahoe when two variables are analyzed: The water is at a height of 6228 feet and the forecast runoff shows them the lake would exceed the maximum legal limit when the snow melts or heavy rain is on the horizon.

Chief Deputy Federal Water Master Dave Wathen said they opened the dam gates at Tahoe City on February 23 and began spilling water from the lake into the Truckee River. He said they expect 2.1 feet of water to hit Lake Tahoe during the spring (April through the high, usually July) snowmelt runoff which would put more water into the lake than legally allowed. Out of the 17 gates, 11 are open.

The water at the dam has been running at a rate of 1200 cubic feet per second (cfs) which is equal to two-hundredths of a foot of water from the lake. 1200 cfs is equal to 2380 acre feet per day.

Why a legal limit?

Federal law prohibits storage of water in Lake Tahoe above 6,229.1 feet, which is the limit decreed in the 1935 Truckee River Agreement. The same agreement appointed a Federal Water Master to manage storage and diversions on the Truckee River and established certain minimum and maximum flows at the Farad gaging station near the state line.

From author Mark McLaughlin:

The epic winter of 1906-07 dumped a record 73.5 feet of snow on the Sierra. The deep snowpack melted rapidly when torrential rain soaked the region in late February and March. Concerned about dangerously high water levels behind the dam, the power company prematurely released too much water, which cut short the amount available for Nevada farmers. The on-going Tahoe water war generated intense passion and anger between neighbors in the watershed. Despite their conflicts, the many users of Lake Tahoe’s water—property owners at the lake, the power company and its customers, farmers, ranchers, and Indians—all realized they had a vital interest in anticipating the seasonal rise and fall of the lake.

During the snowmelt period in spring, high water in Lake Tahoe frequently eroded the lake’s shoreline. In 1909 lakeside residents issued an ultimatum to the Truckee River General Electric Company (the predecessor of present-day Sierra Pacific Power Company) insisting that Lake Tahoe must be lowered sufficiently each winter to preclude all possibility of spring flooding. Dissatisfied with the utility’s response to their demands, in 1913 residents sued claiming that artificially high water levels were damaging the Tahoe shoreline and eroding tons of soil, which affected water quality and clarity. The Truckee River is probably one of the most litigated waterways in the country.