Wow! I used to frequent that part of the river (Topock, Needles) quite a bit since the early 70's through the mid 90's. When did they do that?
Evidentally quite a while ago.. closed down their plant in the area and dumped into the sand and left, don't know what they thought would come of the effluent. ADEQ has a site to track the cleanup effort.
PG&E Outlines Chromium Cleanup
by Paul LaVoie, TSN
TOPOCK, AZ - Pacific Gas & Electric is correcting its handling practices of a cancer-causing causing compound it released near the Colorado River over 50 years ago. The utility is proposing to decontaminate an aquifer found to contain high levels of chromium-6 near it's compressor station in California located a half-mile southwest of the town of Topock on I-40.
In its most recent report, the California Regional Water Quality Control Board found that from 1951 to 1964, PG&E discharged untreated wastewater containing hexavalent chromium from a compressor station cooling tower to "percolation beds" in Bat Cave Wash, a stream bed that empties into the Colorado River. An aquifer of chromium-6 contaminated groundwater has since accumulated near the river, and in 2004 PG&E began pumping the contaminated water and transporting it to a hazardous waste handler. The plan for disposal of carcinogenic waste water is complicated, but poses little or no threat to the environment. PG&E will drill a series of wells both in and around the aquifer.
Three of the "injection wells" will each hold 6,000 gallons of a food-grade, sodium lactate solution designed to reduce the chromium-6 contamination to a non-hazardous chromium-3 state.
The California Regional Water Quality Control Board's complete findings can be found online, and include a site map of the contaminated area. The board will consider the revised proposal in a public hearing on January 18th at 10:00am, at the regional offices located in Palm Desert, California.
Additionally, the findings noted the PG&E disposal plan could affect the way future chromium-6 contaminations are handled, depending on the results at the Topock compressor station.