Originally posted at Voice of San Diego.
By Lisa Halverstadt.
California is experiencing one of its driest stretches yet but San Diego County’s water agency isn’t alarmed.
In the weeks after Gov. Jerry Brown declared a drought emergency, the San Diego County Water Authority has repeatedly said past efforts to diversify its water sources and hold more H20 in storage mean our region can avoid the significant cutbacks others have seen.
The water agency’s board did vote Thursday to begin urging cities and agencies that rely on it to usher in voluntary belt-tightening. But that move is far less drastic than the 20 percent cuts the governor urged last month.
That relatively rosy outlook didn’t come without a major trigger.
In the early 1990s, San Diego relied on one major source for almost all its water: the Los Angeles-based Metropolitan Water District of Southern California, which draws much of its H20 from the Colorado River and theSacramento-San Joaquin Delta.
Here’s what that looked like.
But a drought that hit its peak in early 1991 nearly stung the region when Metropolitan threatened to halve its allocation to San Diego County. Rain and snow ultimately saved San Diego, but business leaders and residents demanded that the county diversify to avoid a future disaster.
The County Water Authority responded. Today it only gets about half of its H20 from Metropolitan, relying on a handful of new sources to lessen that burden.
The percentage listed as “Conservation” isn’t an actual water source. It comes from the Water Authority’s assumption that efforts to save water since 1991 makes more available than there would have been without San Diegans cutting back.
San Diego water wonks want to diversify even more by 2020.
So where’s all this new water coming from?
Imperial County Farmers
The biggest chunk comes from a 2003 pact with Imperial County. It basically allows San Diego to pay Imperial County farmers for H20 they’d otherwise use to water crops.
The deal has already brought significantly more water to San Diego. By 2021, officials hope to get 200,000 acre-feet of water annually from the arrangement, about double what San Diego received from the Imperial Valley farmers last year. To put that in perspective, an acre foot is enough to serve about two households a year. So this means Imperial County water would service about 400,000 households in 2021.
Canal Linings
San Diego relies on two pathways to get much of its water: the Coachella and All-American canals.
For a long time, the region lost out on a lot of H20 while it was still on its way here. Hundreds of thousands of gallons of water seeped into dirt as it traveled through the canals.
That changed several years ago when construction crews laid these concrete linings along those two canals to save all that lost water.
The Water Authority can get as much as 77,700 acre-feet of water annually thanks to this relatively simple fix, which would serve about 155,400 households.
Conservation
San Diego residents and business owners have cut back considerably in the last couple decades.
The region is using slightly less water than it did in 1991, when the county had roughly 2.5 million residents. The population is now closer to 3.2 million.
And since 2007 alone, Water Authority figures show total regional water use has fallen about 22 percent. The numbers below are presented in acre-feet.
Pushes for more efficient appliances and ideas from statewide task forces on conservation have also contributed to the drops in usage.
Recycled Water
The Water Authority and some of the cities and agencies under its umbrella are pushing a relatively new water source: extensively treated wastewater that can be used for irrigation or perhaps even refreshment.
The city of San Diego has conducted a handful of pilot studies on adding recycled water to the region’s general supply. Last year, 10 North County water agencies came together to increase necessary infrastructure to boost recycled water use for irrigation.
Some of these efforts are already paying off.
In 2013, the county had more than 27,000 acre-feet of recycled water in its supply. It hopes to almost double this amount by 2020.
Groundwater
San Diego can’t access groundwater supplies as easily as many parts of the state. But about seven water agencies in the county produce it. Camp Pendleton has been most successful, delivering about 7,000 acre feet of salty, brackish water a year. That makes up a sizeable chunk of the roughly 21,000 acre-feet of water that the county recorded from this source last year. Groundwater is processed and made drinkable before being added to the water supply.
Oceanside is one city that’s aiming to up its groundwater delivery. Late last year, the city installed a new pump station it projects will bring in about a 27 percent hike in usable groundwater H20.
San Diego Area Reservoirs
Rainfall and runoff stored in San Diego area reservoirs make up the county’s largest local water source. These reservoirs hold enough water to fill more than 384,000 large swimming pools.
On average, these local surface water sources make up about 7 percent of the region’s annual water supply.
In recent years, the County Water Authority has tried to increase its storage, essentially to create an insurance policy for future droughts.
The Water Authority keeps tabs on 25 reservoirs. Two of the largest are El Captain and San Vicente, both owned by the city of San Diego.
Water in these reservoirs – as well as those outside San Diego – also accounts for the stored water that the Water Authority says makes it confident the region will have enough water to get through 2014 even if the drought continues.
Dana Friehauf, the Water Authority’s acting water resource manager, said the Metropolitan Water District’s storage reservoirs have also helped shield San Diego County from the water cutbacks necessary elsewhere.
Major Metropolitan water storage caches include Diamond Valley Lake near Hemet and Lake Matthews in Riverside County.
These H20 stockpiles act as a sort of an insurance policy for all Southern California water agencies, Friehauf said.