Water isn't the only resource running short in California. The drought-stricken state is also low on natural gas. With a move that usually comes in the height of summer when temperatures are soaring and air conditioners blasting, Californians were urged to voluntarily cut their electricity use after frigid weather across the U.S. and Canada caused a shortage of natural gas at Southern California power plants. The so-called Flex Alert, in which residents are asked to turn off unneeded lights, avoid using large appliances or equipment, and turn off electrically powered heaters, was allowed to expire at 10 p.m. Thursday, nine hours after it began. (Read more: Cold blast pushesrecord natural gas demand) The shortage was only in Southern California, but the north was asked to do its part too.

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"Statewide electricity and gas conservation will help free up both electricity and gas supplies for Southern Californians," the California Independent System Operator, which runs the state's power grid, said in a statement. There was no immediate call for an extension of the alert, but it wasn't clear whether more could be coming. Stephanie McCorkle, a spokeswoman for the grid operator, said Southern California has become increasingly dependent on natural gas-fired plants since the decision last year to shutter the troubled San Onofre nuclear power plant, which is located between Los Angeles and San Diego. When it was operating, the twin-reactor San Onofre plant produced enough power for 1.4 million homes. (Read more: ) According to 2010 California Energy Commission research, 53 percent of the power generated in the state comes from natural gas.