District 4 Supervisor Gary Wyatt said the only way to protect the region's air quality is to oppose the building of any power plants in the air basin.
"Clean air is a very valuable thing," he said, adding poor air quality will lead to lower quality of life, which in turn will preclude new development and families from moving to the county.
District 3 Supervisor Joe Maruca urged the county to take a "combative stance" against all the power plants.
"They're still going to put crap in the air," he said.
Sempra local government affairs manager Bob Nicksin urged the board to separate its displeasure toward the power plant from the proposed gas pipeline.
He also said the energy company — parent of San Diego Gas & Electric and Southern California Edison — has met with local air pollution control district officials and agreed to address a number of local concerns.
As a result, Sempra has agreed to install the latest controls for nitrogen oxides, with a limit of 2.5 parts per million air emissions; install the latest controls for carbon monoxide, with a limit of 4 ppm; and continuous emissions monitoring, with the data provided to the county.
Nicksin said in return for the concessions, Sempra would seek county support.
"We would still very much like to have your support on this issue," he said.
Meanwhile, several American Indians in the Palo Verde area are opposed to the pipeline.
Blythe resident and Chemehuevi tribe descendant Alfredo Figueroa said the pipeline will cross through sacred Indian sites including a cremation area.
"We're here to defend Mother Earth," Figueroa said. "We don't need these power plants."
The $230 million, 215-mile, 36-inch natural gas pipeline is owned by PG&E Corp., Sempra Energy International and Próxima Gas S.A. de C.V.
In other actions, the board approved the Planning Department and Air Pollution Control Office responses to the pipeline's draft environmental impact statement to the Federal Energy Regulatory Commission.
Staff Writer Rudy Yniguez can be reached at 337-3440.