A newly released AWWA study of perchlorate occurrence nationwide found the rocket-fuel contaminant in 26 states and Puerto Rico, mostly at levels below 12 micrograms/L. Conducted by HDR with funding from the Water Industry Technical Action Fund, the study also found that:
* The majority of detections were not associated with documented releases of perchlorate;
* Perchlorate was detected in approximately 5% of the nation's large community water systems;
* Less than 1% of all drinking water systems would be affected by a maximum contaminant level (MCL) of 20 micrograms/L, while that number would rise to 4 percent (10 percent in California) if the MCL were set at 2 micrograms/L;
* The highest densities of perchlorate occurrence were found in Southern California, west central Texas, Massachusetts and along the East Coast between New Jersey and Long Island; and
* No difference was found in the rate of perchlorate occurrence between surface waters and groundwater.
Occurrence was analyzed and geographically mapped by compiling data from existing databases, including the Unregulated Contaminant Monitoring Rule and studies by the states of Arizona, California, Texas and Massachusetts.
Report authors conclude that their estimates "underrepresent the impact of perchlorate on small systems and surface waters" and that the actual occurrence of perchlorate "is likely to be greater than currently estimated in this report. However, it is not anticipated that the percentage of systems impacted by perchlorate will be significantly greater than estimated by this report."