A natural gas shortage triggered by extreme cold weather in much of the U.S. and Canada has affected supplies to power plants in drought-stricken California and forced the California Independent System Operator (CAISO) on Thursday to issue a conservation alert.

CAISO said the natural gas shortage was only affecting Southern California but appealed to customers across the state to reduce their energy use to help free both electricity and gas supplies for Southern California.

A years-long drought is severely afflicting the state. Nearly 60% of the state is now classified as being in a condition of extreme drought, prompting its governor on Jan. 17 to declare a state of emergency. California has almost 14% of the nation’s total hydro capacity and a 33% renewables mandate, but it has been relying on in-state generators fueled by natural gas and imports of electricity.

It has also sought to offset the loss of generation from the 2.3-GW San Onofre Nuclear Generating Station, which was permanently retired last year, by adding several new generating units with a total capacity of 205 MW.

Meanwhile, trades for Friday delivery of natural gas at the Henry Hub in Louisiana averaged $9 per million British thermal units on Thursday—the highest average price in more than five years. A year ago, prices averaged at just $3.34/MMBtu.

In an update to the Federal Energy Regulatory Commission (FERC) on the bulk power system’s performance during the cold snap in mid-January, staff credited a “good outcome” to “many system operators and other utility personnel who worked long and hard, and communicated extensively with each other to keep the grid up and running.”

But it also noted that the Midwest, Northeast, and Southeast regions set record demands for natural gas, while other parts of the Eastern and Central U.S. were near their all-time peaks.

—Sonal Patel, associate editor(@POWERmagazine, @sonalcpatel)