California drought: Two reservoirs near Hetch Hetchy tapped

Marisa Lagos in the San Francisco Chronicle: The San Francisco Public Utilities Commission is in a much better position than most other California water agencies as the state stares down its first full year of drought: Its Hetch Hetchy Reservoir remains 51 percent full, and its customers use far less water than most others.

But if the bone-dry conditions persist, it won't be. So the agency, which serves 2.4 million Bay Area water customers, is making contingency plans to increase its drinking supply by using two existing reservoirs just northwest of its Yosemite crown jewel that the city hasn't tapped for drinking water since 1988.

Lake Eleanor and Cherry Reservoir, which the SFPUC now uses for hydropower and to provide water to several districts downstream, sit high in the Sierra Nevada amid the devastation of last year's huge Rim Fire. To bring those reservoirs into the drinking water system, the agency will need to spend about $10 million to shore up a dam that was damaged in the wildfire and make improvements to an aqueduct that hasn't been used for more than two decades.

Unlike Hetch Hetchy, which can hold 360,000 acre-feet and is so pristine its water needs minimal treatment and no filtration, Lake Eleanor and Cherry Reservoir - also known as Lake Lloyd - will have their water filtered at an existing Sunol Valley treatment plant. The PUC hopes to have the new system online by Oct. 1, well in time for 2015's dry season. Over the coming months, the SFPUC expects Cherry Reservoir to fill to its capacity - 273,000 acre-feet - with snowmelt from the watersheds that feed it. Lake Eleanor, at 27,100 acre-feet, is already filled to the brim....

Lake Eleanor and the Banning Dam in the Santa Monica Mountains (I hope this is the right body of water), shot by Seanydelight, Wikimedia Commons,  under the Creative Commons Attribution-Share Alike 3.0 Unported license