The National Weather Service estimates that more than 6 billion gallons of water have poured into Lake Tahoe in less than two days, as the lake recovers from four years of drought. Since midnight Monday, the lake level has gone up 1.92 inches, the equivalent of 6.39 billion gallons of water. The water comes as a winter storms slam the Sierra, bringing several feet of snow to higher elevations, and rain at lake level, which sits at about 6,200 feet.