SoCal water reserves could dry up in 2016

 

The nearby photo shows the recent demolition of a 160-foot water tank tower at Edwards Air Force Base northeast of Lancaster. Could it be a prophetic image for Southern California’s future?

The Associated Press reported the area’s regional water supplier, the Metropolitan Water District of Southern California, could be without reserves by early 2016.

The MWD supplies water to 19 million people in cities in six counties in Southern California: Los Angeles, Orange, Ventura, Riverside, San Bernardino and San Diego.

This stark news is based on the announcement that the MWD already has drained two-thirds of its backup water supplies.

In May 2013, the MWD announced its reserves of 2.6 million acre-feet of water were “the fullest they’ve ever been.”  Going into the 2014 water year, MWD said it had adequate water reserves even after two consecutive prior dry years. But the long drought now has parched reserves.

MWD storageoOverview

The MWD mainly depends on its 800,000 acre-foot Diamond Valley Lake reservoir in Riverside County for backup water supplies in the event of drought or emergencies. As of Sept. 22, current storage at Diamond Valley Lake was 401,000 acre-feet, or 51 percent of capacity.

Other MWD storage reservoirs are:

• Lake Mathews near the city of Riverside. It has has 182,000 acre-feet of storage capacity. And as of Sept. 22, it had 59,194 acre-feet of current storage, or 33 percent of capacity. Lake Mathews is where water from the Colorado River is stored in Southern California.
• Lake Skinner Reservoir near Rancho California. It has a total capacity of 44,000 acre-feet of water and was in better shape with 33,854 acre-feet in current storage, meaning 77 percent full.

MWD groundwater storage resources

MWD also has 350,000 acre-feet of potential water storage capacity in the Arvin-Edison Groundwater Storage District in Kern County.

There also are about 437,889 acre-feet of potential groundwater storage arrangements that the MWD holds in scattered water basins around Southern California.

The MWD also has arrangements with nine of its member water districts to store water in local groundwater basins.  This is called “conjunction use.”  As of July 21, 2013, about 67,400 acre-feet of water was held in these groundwater banks.

However, how much of MWD’s groundwater storage supplies may be available given the massive loss of groundwater due to evaporation during the 2014 drought remains to be seen.

Lake Mead storage

Instead of storing it in local reservoirs, the MWD also banks some of its allocation of Colorado River water in Lake Mead.  About 280,000 acre-feet of its 330,000 acre-feet of stored water may be withdrawn by the end of the “2014 water year,” which ends on Sept. 30.  About 50,000 acre-feet is available for carry-over into 2015.

North of Los Angeles, the state of California has three reservoirs where it stores water from the Sacramento Delta. The situation as of Sept. 23:

• Castaic Lake, with 325,000 acre-feet of storage, was at 36 percent of capacity.
• Pyramid Lake, with 171,000 acre-feet of water storage, was at 94 percent of capacity.
• Lake Perris in Riverside County, with 131,452 acre-feet of storage, was 43 percent of capacity.

Grand total storage going into 2015

Excluding uncertain groundwater storage levels, as of Sept. 2014, MWD has about 494,048 total acre-feet of water in surface water reservoirs going into 2015, according to CalWatchdog.com‘s calculations.

There are also about 384,264 acre-feet of water parked in federal and state reservoirs in Southern California.  Estimated total carry-over water going into 2015 is about 878,312 acre-feet, excluding groundwater storage.

All totaled, this would be enough water for about 5,269,872 people out of MWD’s 19 million-person customer base, or water for 28 percent of the population.

So if 2015 ends up another dry year, Southern California could be forced to have mandatory water rationing by 2016.