62 Days Until 17-Acre Emergency Reservoir Tops Off

More than 240 million gallons of water are flowing into a 17.8-acre reservoir that will keep San Clemente, San Juan Capistrano and other south Orange County residents from seeing their faucets go dry in an emergency.

Water began streaming July 18 into the $53.7-million Upper Chiquita Reservoir in Rancho Santa Margarita. It is expected to be completely filled up by September, providing a "buffer" from disruptions in water imports and a "hedge" against natural disasters.

The other agencies that will draw on the reservoir are the Moulton Niguel, Santa Margarita and South Coast water districts.

San Clemente, which has its own independent water utility, which agreed to pay $5.53 million for the reservoir contruction, an $11.7 percent share that will guarantee the city 27.4 million gallons of storage capacity.

The unit is considered to be the first large-scale emergency potable water reservoir built in Orange County in decades. The water was purchased from Metropolitan Water District, a wholesale water supplier that delivers to most of Orange County.

Located on the western slope of Chiquita Canyon, just north of Oso Parkway, the reservoir took two years to build, and required excavation of 1.4 million cubic yards of dirt from the canyon floor.

For $5.1 million, San Juan's share of the reservoir is 24.8 million gallons.

The city operates its own Groundwater Recovery Plant, fed by local wells and imported drinking water from Metropolitan Water District of Southern California.

MWD sends the water—tapped from state-owned reservoirs and aqueducts north of Pyramid Lake, and from the Colorado River—to the Diemer Filtration Plant in Yorba Linda, where it's purified and tested to meet federal standards. It's then piped to the plant next to San Juan Capistrano City Hall on Paseo Adelanto.

As the water traverses California, it's subject to earthquakes, fires and other natural disasters that could destroy the pipes through which it flows and leave local residents without drinking water. The Chiquita Reservoir could also supply residents during planned outages of the Diemer Filtration Plant, which is shut down one week per year for routine maintenance.

"The partners of the [Upper Chiquita] reservoir are entitled to the water when needed," said Michele Miller, a spokeswoman the Rancho Santa Margarita Water District.

--Adam Townsend contributed to this report.