EPA Proposes an MCL for Perchlorate

The U.S. Environmental Protection Agency released on May 23 a prepublication notice of proposed rulemaking asking for public input on a range of options regarding the regulation of perchlorate in public drinking water systems.

Specifically, the EPA is seeking comment on setting a proposed National Primary Drinking Water Regulation for perchlorate to establish a maximum contaminant level (MCL) and maximum contaminant level goal (MCLG) at 56 micrograms per liter. The three regulatory options are:

  1. An MCL and MCLG set at 18 micrograms per liter
  2. An MCL and MCLG set at 90 micrograms per liter
  3. Withdrawal of the agency’s 2011 determination to regulate perchlorate in drinking water.

Additionally, the EPA has requested comment on perchlorate monitoring and reporting requirements for public water systems and treatment technologies to comply with the MCL, including affordable technologies for small systems serving 10,000 or fewer people.

Perchlorate is used in rocket propellants, munitions, fireworks, airbags, matches, and flares. Perchlorate may occur naturally, particularly in arid regions, and is an impurity in hypochlorite solutions used for drinking water treatment and nitrate salts used to produce nitrate fertilizers, explosives, and other products. Contamination has been found in water wells in 22 states.

The EPA is accepting public comments for 60 days after publication in the Federal Register at www.regulations.gov (Docket ID No. EPA-HQ-OW-2018-0780). NGWA will work with a group of volunteers to prepare comments on the proposal.