Chromium 6, the toxic element made infamous by the movie Erin Brockovich, is back in the news. In Southern California and central Arizona, water officials fear that the chemical might contaminate drinking water for some 20 million people, as it creeps toward the Colorado River from a pump station on a natural gas pipeline in the Mojave Desert.
Between 1951 and 1964, Pacific Gas and Electric dumped 6 million gallons per year of chromium-tainted water into a wash near Needles, Calif. The chromium was used to prevent corrosion at the Topock pump station, but the contaminated water leached into groundwater. Then it started seeping toward the Colorado River about 40 miles upstream of intakes for the Metropolitan Water District, which supplies Los Angeles and San Diego, and the Central Arizona Project, which supplies Phoenix and Tucson.
When inhaled, chromium 6 is known to cause cancer, but scientists disagree about whether the chemical is a carcinogen in drinking water. Nonetheless, the U.S. Environmental Protection Agency allows no more than 100 parts per billion of chromium in drinking water, while California’s standard calls for less than 50 parts per billion. In December, tests revealed that water with chromium 6 concentrations of 111 parts per billion was only 125 feet from the Colorado River. About 600 feet from the river, concentrations reached 11,000 to 12,000 parts per billion.
Pacific Gas and Electric is still determining how to clean up the pollution permanently. In the meantime, in early March, the company began pumping 26,000 gallons of contaminated water per day from the Topock site. The Metropolitan Water District has also asked Pacific Gas and Electric to protect the Colorado River with an underground barrier 1,600 feet long and 100 foot deep, a project that could take a year to complete." Our focus is to prevent anything on-site from getting to the river," says Bob Muir, spokesman for the Metropolitan Water District. "It’s an imminent danger."