"4.2 million customers from Bakersfield to the Oregon border." In the 1950s and 1960s, at both Topock and Hinkley compressor stations, hexavalent chromium in the form of an additive was used in rust-prevention in "the cooling towers that prepared the gas for transportation through PG&E's pipeline to northern and central California." These cooling waters were then disposed of "adjacent to the compressor stations." Topock Compressor Station is located in eastern San Bernardino County, California, approximately southeast of Needles, along the Colorado River. In 1996 following the Hinkley groundwater contamination lawsuits related to the dumping of hexavalent chromium, PG&E began "an investigation and cleanup process governed by the federal Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). PG&E continues to provide reports on their soil investigation and remedial activities at the Topock compressor station site regarding potential future impacts to the Colorado River and to Arizona's groundwater. See also Bullhead City, Arizona Fort Mohave, Arizona Mohave Valley, Arizona Yucca, Arizona Santa Claus, Arizona References External links Construction of Red Rock Cantilever Bridge nearing completion in 1890. Below Needles. from hdl.huntington.org Huntington Digital Library, accessed June 30, 2015. Building of the Topock Bridge. The steamer is the "Gila." from hdl.huntington.org Huntington Digital Library, accessed June 30, 2015. Train crossing completed bridge at Red Rock Cantilever Bridge. from hdl.huntington.org Huntington Digital Library, accessed June 30, 2015. Unincorporated communities in Mohave County, Arizona Communities in the Lower Colorado River Valley Lower Colorado River Valley Unincorporated communities in Arizona Arizona populated places on the Colorado River