Lake Tahoe reaches natural rim for first time since June 2015

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TAHOE CITY, Calif. (KOLO) -- The wet winter has proven useful for Lake Tahoe. For the first time in 10 months, the lake reached the its natural rim Saturday, April 9, 2016. This last happened in June of 2015 when the lake stayed at or slightly above the rim for a 5 day stretch between June 10th and June 15th. Prior to that, the lake had been below the rim since October 16, 2014.

Rising above the rim is a significant benchmark for the success of a water year. In early December, just as the wet season was beginning, the lake as more than 1.5 feet below its natural rim. In the time since, the lake has made significant rebounds due in part to an average seasonal snowfall, and more recently, the start of the spring melt. According to the National Weather Service in Reno, 60 billion gallons of water have flowed into the lake since early December.

Unfortunately, reaching the rim does not mean we will immediately see significant flows in the Truckee River at Tahoe City. The lake will have to rise several inches above the rim before that happens. Lake Tahoe is unlike a manmade reservoir which can pull water from the bottom of the lake. Instead, water must flow over the rim and into the Truckee River. It could still be several weeks before we see enough water in the lake to create more than a trickle of flow. It will happen this season though. On April 1st, water managers told KOLO 8 News Now they expect the lake to rise a foot to a foot and a half above the rim this summer.

According the U.S. Geological Survey data, the last time the lake contributed significant flows to the Truckee River was sometime between late August and early September 2014. Soon after, the lake fell below the rim and has stayed there ever since, with the exception of those 5 days in June of last year.

We’re still a long ways off from being where water managers would like us to be with Lake Tahoe. There is a total of six feet of storage capacity on top of the lake. Upon reaching the rim Saturday, Lake Tahoe will jump from negative capacity to 0% capacity. An additional 242 billion gallons of water would have to flow into Lake Tahoe for it to reach maximum capacity – something that will not happen this year.

While unlikely, it is possible the lake could reach maximum capacity next year. According to information provided by the Truckee Meadows Water Authority, the lake made such a jump between November of 2005 and June of 2006 when it rose 5.23 feet in 7 months, the second quickest recorded rise in the lake’s history.