PALM DESERT, Calif. -

Coachella Valley residents are invited to join a workshop in Palm Desert today that will explain the impact on their pocketbooks if a state proposal to raise drinking water standards to reduce levels of chromium-6 takes effect.

The Coachella Valley Water District and the Riverside County Board of Supervisors are both opposed to a California Department of Public Health plan to limit chromium-6 to 10 parts per billion in wells and reservoirs throughout the state.

The health department is giving concerned parties until Oct. 11 to submit comments on the proposal, which if approved, would take effect immediately under a regulatory scheme enacted by the Legislature in 2004.

The Board of Supervisors Tuesday unanimously approved a resolution asking the state to reassess the proposal in the interest of sparing ratepayers exorbitant costs.

``This is a very big problem looming for us,'' said Supervisor John Benoit. ``It's noble to ensure the cleanest drinking water available. But this is a standard that's not applicable anywhere else in the nation.''

The Coachella Valley Water District will hold a public workshop at 6 p.m. at the Steve Robbins Administration Building, 75515 Hovely Lane East.

According to organizers, residents will be informed about the proposed new drinking water standards and how they can submit comments to the health department.

CVWD Environmental Services Director Steve Bigley said last week that half the valley's aquifers would be affected by the state plan. Bigley noted that chromium-6 levels in area wells range from 9 parts per billion to 22 parts per billion. He explained that 10 parts per billion is equivalent to 10 drops of liquid in a 10,000-gallon swimming pool.

Chromium-6, also known as hexavalent chromium, received notoriety in the film ``Erin Brockovich'' for its impact on the residents of Hinkley, California.

In that case, carcinogenic levels turned up in drinking water as a result of industrial pollution. However, according to Bigley, most of the chromium-6 in Coachella Valley groundwater can be traced to natural soil erosion at or near quake fault lines.

According to Benoit, filtering out chromium-6 at the micron-level proposed by the state entails constructing treatment facilities that are expensive to build and operate -- costs that will have to be passed on to consumers. The supervisor estimated the average Coachella Valley water customer could see his or her bill go up $500 a year if the new standards are put in place.