AMWA submitted comments August 23 in response to EPA’s notice of proposed rulemaking for regulating perchlorate. A nine-page summary of the proposal can be found on AMWA’s website. The proposed rule sets both a Maximum Contaminant Level (MCL) and a Maximum Contaminant Level Goal (MCLG) of 56 parts per billion (ppb), but also sought public input on three alternative regulatory options:
- An MCL and MCLG set at 18 ppb.
- An MCL and MCLG set at 90 ppb.
- Withdrawal of the agency’s 2011 determination to regulate perchlorate in drinking water.
AMWA engaged the Regulatory Committee and after much discussion decided to support EPA’s alternative option of withdrawing the 2011 determination to regulate. The letter states that “based on the occurrence of perchlorate in drinking water systems at the three possible MCLs – which correspond with EPA’s chosen neurodevelopmental endpoints – AMWA agrees with EPA’s determination that this particular proposal does not present a meaningful opportunity for health risk reduction as is laid out in [the Safe Drinking Water Act].”
The reasoning behind AMWA’s conclusion is the low occurrence of perchlorate throughout drinking water systems. The comments cite EPA’s proposal, which states that “at an MCL of 56 μg/L only 2 systems (0.004% of all water systems in the U.S.) would exceed the regulatory threshold. Even at an MCL of 18 μg/L, there would only be 15 systems (0.03% of all water systems in the U.S.) that would exceed the regulatory threshold. Only one system would exceed the alternative MCL of 90 μg/L.” EPA’s occurrence assessment excluded utilities in California and Massachusetts since both states have set their own MCLs, which are lower than any of the MCLs being proposed by EPA.
However, the association goes on to support EPA’s conclusion that, if the determination is withdrawn, “it does not preclude the agency from re-listing perchlorate on any forthcoming CCLs and potentially regulating it in the future based on new available science and data.” Overall, AMWA supports the regulatory approach of the Safe Drinking Water Act Amendments of 1996 and supports the agency’s use of the Science Advisory Board (SAB) for developing the agency’s models which help inform the development of drinking water regulations. AMWA’s comments encourage EPA to continue utilizing the SAB to inform regulatory processes in the future.
The agency now has until December 19, 2019 to finalize a rule based on consent decree. If members have any questions about the letter, please reach out to Stephanie Hayes Schlea.