WASHINGTON - The U.S. Interior Department asked on Wednesday for public comment on a study it will prepare to determine the environmental effect of a $271 million electric transmission line project in southern California. The 500,000-volt line would provide another connection between the transmission systems of Edison International's Southern California Edison and Sempra Energy's San Diego Gas and Electric.

The project's sponsors said the line is needed to make their customers less vulnerable to outages and blackouts.

The companies also said the line would help meet the growing demand for electricity in southern California, where they claim San Diego will suffer from a projected a 46-megawatt (MW) shortfall for electricity in 2005 that will grow to 199 MW in 2006 and increase every year thereafter.

If approved by the California Public Utilities Commission, the 31-mile transmission line would be completed in 2005 and carry enough electricity to light more than 700,000 homes.

A megawatt is enough electricity power about 1,000 homes.

Details of the proposed Valley-Rainbow Interconnection Project were published in today's Federal Register.

The Interior Department's Bureau of Land Management said it would take comment through Feb. 1 on the proposed transmission line and hold a public meeting on the project on Jan. 8 in Temecula, Calif.