California environmental officials said Tuesday that they would require Pacific Gas & Electric Co. to step up cleanup work near a Mojave Desert natural gas facility to prevent a plume of tainted groundwater from seeping into the Colorado River.
The move by the California Department of Toxic Substances Control came in response to high levels of hexavalent chromium, or chromium 6, found Feb. 14 in a 70-foot well about 60 feet from the river. The chemical was used at PG&E's nearby Topock natural gas compressor station about 11 miles south of Needles.
No detectable levels of the carcinogenic chemical have been found in the river, a major source of drinking water for Southern California's 18 million residents. Water for Phoenix and Tucson also comes from the Colorado River downstream from Topock.
"We do not have any indication that the contaminant has reached the river," department Director B.B. Blevins said in a statement. "We have required PG&E to enact the contingency plan as a preventive measure."
Last March, when traces of chromium 6 ranging up to 100 parts per billion were found in wells 125 feet from the river, the state ordered PG&E to pump 20,000 gallons per day of contaminated groundwater to a wastewater treatment plant and test water quality monthly.
PG&E now must test the groundwater at selected wells weekly. The toxic substances department also required the company to increase pumping to the maximum capacity of the treatment system and install an additional well through which more wastewater can be extracted.
The stricter measures were ordered after the Feb. 14 sampling found 354 ppb in one well, over the state's 50 ppb limit for drinking water, department spokesman Ron Baker said.
However, he added, because readings from two shallower wells at the same location did not detect chromium 6, the department needs more data to determine whether the problem is worsening.
Southern California water authorities said it was too early to know whether any action was needed on its part. "We remain concerned with the water quality of the Colorado River," said Jeff Kightlinger, general counsel for the Metropolitan Water District, which operates the Colorado River Aqueduct. "We're going to have to look at this data and see what we have to do."
The Topock facility, a stop along a natural gas pipeline stretching from Texas to the Los Angeles basin, used chromium 6 to control corrosion and mold in the plant's cooling towers. PG&E disposed of the untreated wastewater in nearby percolation beds from 1951 to 1969.
The contamination near Topock is similar to another case of chromium 6 pollution, also involving PG&E, at a compressor station near Barstow in 1987. The case, which occurred near a residential area, inspired the movie "Erin Brockovich."
At least one environmental group welcomed the tighter measures at Topock.
"They need to do it. It's a problem they created and it's a problem they can control," said Elden Hughes, chairman of Sierra Club's California-Nevada Desert Committee. "This is way too close to the water that people drink."
PG&E executives could not be reached for comment.