On February 27, 2015, the California Environmental Protection Agency, Office of Environmental Health Hazard Assessment (OEHHA) adopted a revised Public Health Goal (PHG) of 1 part per billion (ppb) for perchlorate in drinking water. The previous PHG for perchlorate was set at 6 ppb in 2004. The PHG is not the regulatory standard with which water purveyors must comply and, according to OEHHA, exceedances of the PHG do not mean the water is not safe to drink.
The Maximum Contaminant Level (MCL) is the regulatory standard for drinking water and remains at 6 ppb in California for perchlorate. There is no federal MCL for perchlorate. State law requires the State Water Resources Control Board’s Division of Drinking Water to set each MCL as close to the corresponding PHG as is economically and technologically feasible and to place primary emphasis on public health. The previous PHG for perchlorate was set at 6 ppb in 2004. Three years later in 2007 the MCL was also set at 6 ppb.
Many California water purveyors through their trade associations opposed the reduction in the PHG and we expect them to also oppose any corresponding reduction in the MCL. Some of these water purveyors, especially in areas of Southern California where there was widespread use of Chilean nitrate fertilizer on citrus orchards, already purvey drinking water with perchlorate in concentrations above 1 but under 6 ppb and it may be difficult and expensive for them to comply with a more stringent MCL.
The OEHHA fact sheet, final report and response to final comments can be downloaded at: http://www.oehha.ca.gov/water/phg/2015perchlorate.html.