SoCalGas asks customers to use less natgas during cold

(Reuters) - Southern California Gas on Wednesday urged customers to conserve natural gas to avoid straining energy supplies over the next week as cold weather blankets the area, boosting heating demand.

Adequate gas supply has been a hot topic in Southern California since a leak from October 2015 to February 2016 shut SoCalGas' Aliso Canyon gas storage facility in Los Angeles.

After SoCalGas upgraded the facility, its biggest in the state, California regulators allowed the company to start injecting gas into it in July, but limited the amount of fuel the utility could store and withdraw to protect public safety.

The Aliso Canyon limitations, coupled with outages at three pipelines, caused state regulators in November to express concern about the local utility's ability to meet customer demand this winter.

One pipeline (Line 235-2) ruptured in October, damaging a second pipe (Line 4000) nearby. Another pipe, Line 3000, was out of service last winter and is expected to remain out until May.

SoCalGas, a unit of Sempra Energy, expects Line 4000 to return by the end of the year.

Until then, regulators said SoCalGas will only be able to support about 3.7 billion cubic feet per day of demand (bcfd), which is about 0.9 bcfd, or 20 percent, less than last winter. That will improve to 0.45 bcfd below last winter once Line 4000 is back.

Regulators said it was unclear if conservation measures will be sufficient to avoid service curtailments to noncore industrial customers and power plants. Core customers include homes and small businesses.

Temperatures in Southern California are expected to drop into the 40s F (5-10 C) through the weekend.

Separately, SoCalGas sent a notice to residents living near Aliso Canyon that there was an "unplanned release" of gas from the facility on Monday during maintenance. The release was stopped within about 50 minutes and did not present a health or safety risk, it said.

However, Andrew Krowne, creator of a community health tracker app, said people reported numerous symptoms, including headaches, nosebleeds and burning eyes and throats.

Several community groups want the state to shut Aliso Canyon but SoCalGas says it is needed to keep the gas system reliable, especially on the coldest days.

The facility serves more than 11 million customers and provides fuel to 17 gas-fired power plants. About 60 percent of the power generated in California comes from gas.

(Reporting by Scott DiSavinoEditing by Chizu Nomiyama)