Hinkley, CA Pacific Gas and Electric Company compressor station

A Pacific Gas and Electric Company (PG&E) compressor station in Hinkley, California. Although hexavalent chromium occurs naturally in the groundwater of the Mojave Desert, concentrations increased in Hinkley Valley beginning in 1952. This increase occurred because PG&E added hexavalent chromium (chromium-6) to the cooling water, as a rust inhibitor, to prevent corrosion in the cooling towers. They then discarded the cooling wastewater into unlined ponds. From there, hexavalent chromium entered the aquifer. Once in the ground, a plume of hexavalent chromium traveled with groundwater away from the Hinkley compressor station into Hinkley Valley.