JIm Grant/Nevada Appeal News Service Lake Tahoe's level is expected to drop to the natural rim this weekend.
More Lake Tahoe shoreline may make for pleasant strolls along the beach, but it means bad news for the Truckee River.
A dam at Tahoe City allows six feet of water to be stored above the natural rim of Lake Tahoe. But in dry years like this one, there's not much water to store and send on to the Truckee.
The lake on Thursday was .07 of a foot above its rim, allowing only a trickle of water to flow from the dam.
If it's windy over the next few days, the lake could experience enough water evaporation to take it below its rim - two months earlier than last year.
"It doesn't happen very often thank goodness," said Federal Water Master Garry Stone, of the lake going below its rim. "It has happened 19 years out of the last 100."
Last year the lake hit its rim on Nov. 20. Snowstorms raised it back over the rim on Dec. 11, where it has stayed since, according to the Office of the Federal Water Master in Reno.
On Thursday, water flowed from Tahoe into the Truckee River at the rate of two cubic feet per second. Ideally that number would hover around 350 cubic feet per second.
When Tahoe's six-feet of storage is gone, residents of Reno, Sparks and Truckee, as well as farmers along the Truckee River, have to rely on wells and private reservoirs for water, Stone said.
The surface of Tahoe covers 122,000 acres. When the wind is strong enough and sweeps across all that surface area, more than a billion gallons of water are sucked from the lake in one day. Annually, more than 3 feet of water evaporates from the lake, enough water to meet the water supply needs of Reno and Sparks for five years.
Through Monday, Tuesday and Wednesday, 3.5 billion gallons of water evaporated from the lake, according to the Office of the Federal Water Master.
Contact Gregory Crofton at gcrofton@tahoedailytribune.com or (530) 542-8045.