RIALTO - Standing in front of two truck-sized cylinders that scrub a rocket fuel ingredient from the city's drinking water, Sen. Dianne Feinstein, D-Calif., pushed her legislation that seeks $50 million in federal dollars to help clean up the contamination.

"If we don't take action now, this plume will make the groundwater for thousands of people undrinkable," Feinstein said, flanked by the mayors of Rialto, Colton and Fontana, plus county Supervisor Josie Gonzales and state legislators.

It is the largest single proposed contribution by the federal government to assist in the cleanup of wells throughout the state.

Perchlorate, which provides the oxygen for solid rockets, road flares and fireworks, has contaminated hundreds of wells in California, including dozens in San Bernardino County.

The underground plume of contamination she referred to is the one running from north Rialto about six miles into Colton and Fontana. It has affected 22 wells, with nine of those back in operation after expensive treatment equipment was installed.

Feinstein's bill, which would also provide another $8 million for research into new and cheaper cleanup techniques, will be tacked on to a bill by Rep. Joe Baca, D-Rialto, and Rep. Richard Pombo, R-Tracy, passed last year that also provides for cleaning up perchlorate.

"Ninety percent (of the contamination) comes from federal resources, therefore the federal government should take responsibility for the cleanup and not stick local communities with the bill," Baca said.

It costs about $1 million per well to install treatment equipment, and maintaining it can run to more than $200,000 per year.

State water officials and the cities have been pursuing the companies they believe are responsible for the contamination for years.

The perchlorate plume originates near the county-owned Mid-Valley Landfill, where an ammunition storage company operated from the 1940s through the 1950s. The area also has been home to numerous fireworks manufacturers.

B.F. Goodrich has pitched in $4 million for the cleanup so far, and a company affiliated with Black & Decker has been fighting charges that it also bears responsibility.

At a hearing before the Santa Ana Regional Water Quality Control Board next week, the companies are expected to propose that they pay to dig monitoring wells in exchange for delaying any further enforcement action.

Rialto City Attorney Robert Owen, who has sued the Department of Defense and several dozen other potentially responsible parties, said the city would oppose any delay in forcing the companies to take responsibility and start paying their share.

Because most of the contamination throughout the state is in some way connected with defense, Feinstein said the Department of Defense has not done nearly enough.

The Senate rejected attempts by the department to seek legislation to protect it from having to pay for perchlorate contamination, she said.

The Defense Department said it has spent about $59 million on perchlorate cleanups and research.

Baca's bill requires that local communities pay 35 percent, and his son, Assemblyman Joe Baca Jr., D-Rialto, has introduced a bill that would provide state money for local communities to meet the match.

The U.S. Environmental Protection Agency last month ignored the recommendations of its own scientific panel and proposed guidelines for cleaning up perchlorate to a level of 24.5 parts per billion. The state has proposed 6 parts per billion and some scientists think the permissible level should be 1 part per billion.

"I think the EPA has downgraded the significance of this," Feinstein said. "I'm very worried it's gotten into food products, and most impacts will be to nursing mothers and their babies."

Perchlorate is known to reduce thyroid function and the fear is that the chemical could harm the development of fetuses and small children.

Neither the state nor the federal government has established an enforceable drinking water standard, and Feinstein's bill includes language encouraging the EPA to set a standard.