NOAA calculated that in the two-day span from Dec. 9 through 11 Lake Tahoe gained 8,690,131,707 gallons of fresh water.
Last year this time Lake Tahoe's level was 6,222.1 feet, whereas this year the level is 6,225.2, over 3 feet higher. With Lake Tahoe's surface area of 191 square miles, adding three feet of water amounts to a tremendous addition to the lake's water storage. In fact, the total Lake Tahoe volume is estimated at 39 trillion gallons of water.
Lake Tahoe is the second deepest lake in the United States and is fed by 63 tributaries that drain 505 square miles known as the Lake Tahoe Watershed. Although approximately half of the water entering the lake is from rain or snow falling directly onto the lake surface. The only outlet is the Truckee River, but doesn't tell the whole story of water leaving the lake. In fact, some estimates point to over 100 billion gallons of water evaporates from the lake every year. This is enhanced by the high elevation, low cloud cover and large surface area of the lake.