From May 2005 to June 2005, the Arizona Department of Environmental Quality conducted a study, Potable Well Sampling Task 4.0, to determine if the chromium and chromium VI plume due to the discharge of the Pacific Gas and Electronic Topock Compressor Station has migrated under the Colorado River and impacted water supplies in Arizona. The ADEQ investigated the total chromium and hexavalent chromium (chromium VI) concentrations in (1) public water supply wells, (2) combined industrial and domestic water supply wells, and (3) private domestic water supply wells at Topock and Golden Shores, Arizona. The communities of Topock and Golden Shores have expressed their concerns regarding the findings. Thus, the ADEQ requested the Arizona Department of Health Services to evaluate the potential health effects of exposure to well water contaminated with chromium.

The Arizona Department of Environmental Quality and the California Department of Toxic Substance Control worked together to assess background levels of naturally occurring metals in groundwater wells at Topock and Golden Shores, Arizona. The communities expressed concerns regarding the findings, thus the ADEQ requested the Arizona Department of Health Services to evaluate whether these naturally occurring metals in groundwater wells are present at levels that may cause adverse health effects.