The EPA has proposed 30 chemical contaminants/groups for its 4th Unregulated Contaminant Monitoring Rule (UCMR 4). The Safe Drinking Water Act (SDWA) specifies that the UCMR must list no more than 30 contaminants or groups—called the contaminant candidate list (CCL)—and that the EPA must produce a revised list every 5 years. Also, as required by the SDWA, the EPA must determine every 5 years whether or not at least five contaminants from the CCL warrant regulation.
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The proposed CCL includes 10 cyanotoxins/groups. Cyanotoxins can be produced by cyanobacteria contained in algal blooms. When present in water used as a source of drinking water or in recreational water, cyanotoxins can have adverse health effects on humans and wildlife.
The remaining entries on the proposed list are two metals; eight pesticides plus one pesticide manufacturing by-product; three brominated haloacetic acid groups of disinfection by-products; three alcohols; and three semivolatile organic chemicals.