LAKE ELSINORE - A transmission line that would connect a controversial hydroelectric station to two power grids is in the crosshairs of a Riverside County supervisor, who today will ask his colleagues to weigh in against the line.

The county Board of Supervisors has not taken a position on the line or the Lake Elsinore Advanced Pumping Station. The station would pump water uphill at night when electricity is more readily available; the same water would fall back through turbines during the day to generate electricity when it's in higher demand.

But Supervisor Bob Buster, whose district includes Lake Elsinore and points west, wants the transmission line and the pumping-generating station to undergo environmental review together. The Nevada Hydro Co. asked the California Public Utilities Commission last month to approve the 30-mile transmission line independent of an environmental study for the station.

The 30-mile link would be one of two major high-voltage lines connecting the grid operated by Southern California Edison in Orange, Riverside and San Bernardino counties with the one operated by San Diego Gas & Electric Co. The link would run from an Edison line north of Lake Elsinore to one that already connects Escondido with Camp Pendleton.

Buster said the high-voltage line could hurt the quality of groundwater, disturb nearby residents and schools and create a fire hazard in the forest. At a minimum, Buster contends, the project should get a full review under the California Environmental Quality Act, which could require the developers to offset the full range of impacts, for example by compensating local governments or by funding conservation projects.

"The environmental review process should not be sacrificed (for) a project that will cost power to make power," Buster wrote in a draft letter that the Board of Supervisors could send to utility regulators after a vote today.

In an interview Monday, Buster said he's beginning to wonder if Nevada Hydro is actually more eager to build the transmission line, with or without the pumping-generating facility.

"We were keeping an open mind about the pumping-storage project, which could - and I underline 'could' - bring benefits to the Lake Elsinore area," Buster said. "They see this as a replacement for the Valley-Rainbow connection. The signs here are alarming to me."

The board is scheduled to meet at 9:30 a.m. at 4080 Lemon St. in downtown Riverside.

SDG&E proposed the Valley-Rainbow line in 2000 to connect its own grid at Rainbow to Edison's grid 20 miles to the north in Romoland. But the utilities commission blocked the proposal amid public outcry.

The line now under consideration would similarly ensure a more reliable power supply for the San Diego area, which now must import electricity from Arizona and from the Edison zone via a high-voltage line that passes alongside the nuclear generating station at San Onofre, said Chris Wysocki, a spokesman for Vista-based Nevada Hydro. But the company and its partners in the project, which include the Elsinore Valley Municipal Water District, would not build the 30-mile link without the pumping-generating station, Wysocki said.

The station just west of the lake would make use of power generated at night, including power from a wind farm planned for the Bakersfield area. Without an immediate use to consumers, the power would be used to pump water from the lake up into the reservoir. The water would be released during the day when factories, offices and air-conditioners demand it, spokesman Chris Wysocki said.

The new transmission line would cost $350 million to erect, Wysocki said. The station is expected to cost $800 million on top of that.

Wysocki also said he believes a completed federal review was thorough enough.

"The environmental review of this has been 12 years in the making," Wysocki said. "Environmental mitigation is something we always have been and always will be sensitive to."

- Contact staff writer Chris Bagley at (951) 676-4315, Ext. 2615, or cbagley@californian.com.