The graph just below shows the dramatic change in lake level during the present week. The Gauge height on the left axis displays the distance above 6,220 feet in altitude. So if the Gauge height reads 6.05 feet, the actual altitude of Lake Tahoe surface is 6,226.05 feet.

Lake Up 4.8 inches
On the graph the line shows the level of the lake moved from 6.05 to 6.45 in four and one-half days this week--though noon on Friday. This is a 0.4-foot change, or 4.8 inches. In terms of altitude, the lake moved up from 6,226.05 to 6,226.45 (6,220 + 6.45 = 6,226.45 feet) feet. The gauge measuring the lake level is at the U.S. Coast Guard station in Lake Forest, just east of Tahoe City.

This lower graph shows the level of the lake during the last 30 days.


From Lake to River at the Dam
The surface level of Lake Tahoe is controlled at the 17-gate, Tahoe City dam. At present, only one gate is open. By law, the lake surface must remain in the range between a low of 6,223 feet (the lake's natural rim) and a maximum allowable height of 6,229.1 feet, which was established by a Federal Court. So the 6.1 feet of difference between high and low is a "reservoir" of water sitting at the top of Lake Tahoe for downstream users. The 6.1 feet reservoir generally fills toward its maximum in the winter; then it is drained by opening dam gates in the summer.


There are 744,600 acre-feet in the 6.1-foot reservoir. An acre-foot is enough water to cover one acre to a depth of one foot--325,851 gallons.

You can look at the gauge readings at the USGS website.