The Safe Drinking Water Act requires the EPA to review existing National Primary Drinking Water Regulations at least once every six years and determine which, if any, need to be revised. In January 2017 (82 FR 3518 – 3552), the EPA announced the review results for the agency’s third Six-Year Review of its National Primary Drinking Water Regulations. Based on the results from that review, the EPA identified eight National Primary Drinking Water Regulations as candidates for revision. The eight candidates are chlorite, Cryptosporidium, haloacetic acids, heterotrophic bacteria, Giardia lamblia, Legionella, total trihalomethanes, and viruses. These eight candidates are regulated through the Microbial and Disinfection Byproducts rules; a series of interrelated regulations that address risks from microbial pathogens and disinfectants/disinfection byproducts in drinking water.
To solicit input on further improving public health protection from microbial contaminants and disinfection byproducts in drinking water and input relevant to any potential rule revisions, the EPA hosted a series of seven virtual public meetings in 2020/2021. These meetings focused on specific microbial and disinfection byproducts topics identified through public comments and information. More information regarding these public engagements is available here: https://www.epa.gov/dwsixyearreview/public-engagements-potential-revisions-microbial-and-disinfection-byproducts-rules.
Following these public engagements, the EPA provided a charge to the National Drinking Water Advisory Council, a Federal Advisory Committee established under Safe Drinking Water Act, to provide the agency with advice and recommendations on key issues related to potential revisions to Microbial and Disinfection Byproducts rules. To support the work of the National Drinking Water Advisory Council the EPA asked the Council to form a working group that included individuals with a variety of backgrounds and expertise. For more information regarding the National Drinking Water Advisory Council, including the Council’s Letter to the Administrator on the Potential Rule Revisions, please visit here: https://www.epa.gov/ndwac/letters-recommendations-epa-administrator-ndwac. For more information regarding the National Drinking Water Advisory Council Microbial and Disinfection Byproducts Rule Revisions Working Group, please visit here: https://www.epa.gov/ndwac/nationaldrinking-water-advisory-council-ndwac-microbial-and-disinfection-byproducts-mdbp.
Under this action, the EPA intends to propose and as appropriate, take final action on revisions to one or more of the Microbial and Disinfection Byproducts rules to further improve public health protection from contaminants relevant to the Microbial and Disinfection Byproducts rules in drinking water and, where possible, to reduce the regulatory burden while maintaining or improving public health protection. Consistent with the 2020 Waterkeepers Alliance v. EPA settlement agreement, the Administrator intends to sign for publication in the Federal Register a proposal to revise the National Primary Drinking Water Regulations for disinfection byproducts and microbial contaminants by July 31, 2025, then publish notice of final action on that proposal by September 30, 2028.
If implemented, revisions to the Surface Water Treatment Rules (rules that are focused on reducing microbial risk in surface water) are anticipated to further reduce exposure to pathogens including Cryptosporidium, Giardia lamblia, Legionella, and viruses in drinking water; these have been linked to diseases including gastrointestinal illness (such as diarrhea, vomiting, and cramps) and Legionnaire’s Disease. If implemented, revisions to the Disinfectants and Disinfection Byproducts Rules are anticipated to further limit exposure to disinfectants and disinfection byproducts. Disinfection byproducts can form in water when disinfectants used to control microbial pathogens react with natural and anthropogenic materials found in source water. If consumed in excess of the EPA’s standards over many years, disinfection byproducts have been linked to adverse health outcomes including carcinogenic, reproductive, and developmental effects. Together, drinking water attributable microbial and disinfection byproducts diseases are estimated to cause tens of thousands of serious illnesses in the United States every year, some of which may be prevented by regulatory revisions to these existing regulations.
A National Primary Drinking Water Regulation establishes requirements applicable to public water systems subject to the rule; as defined by the Safe Drinking Water Act, a public water system provides water for human consumption to at least 15 service connections or serves an average of at least 25 people for at least 60 days a year. The proposed rule could impact Tribal governments that operate public water systems subject to the rule requirements. The proposed rule could also impact Tribal governments that have primacy enforcement authority (primacy) for public water systems on Tribal lands.
Under the Safe Drinking Water Act, the EPA sets public health goals and enforceable standards for drinking water quality. National Primary Drinking Water Regulations include legally enforceable maximum contaminant levels or treatment techniques that apply to public water systems. Maximum contaminant levels or treatment techniques are established to protect public health by limiting the levels of contaminants in drinking water to the extent feasible. The agency is currently in the process of evaluating potential regulatory options to develop proposed revisions to the National Primary Drinking Water Regulations for Microbial and Disinfection Byproducts, including potential revisions to treatment techniques, monitoring, and public notification requirements. The Microbial and Disinfection Byproducts rules currently require some water systems to conduct monitoring, implement treatment, or take other actions to reduce microbial and DBP risks and communicate with customers. The proposed revisions to the National Primary Drinking Water Regulations for Microbial and Disinfection Byproducts may adjust how some public water systems conduct monitoring to determine the level of disinfectant residual and/or disinfection byproducts in their drinking water. Further, some water systems may have to implement new or additional treatment or other actions to reduce microbe and/or disinfection byproducts levels in their drinking water and to communicate with their customers about levels of microbes and disinfection byproducts in their drinking water. The EPA is requesting your input on considerations to inform the development of proposed revisions to these National Primary Drinking Water Regulations and potential regulatory requirements. Additional information can be found at: https://www.epa.gov/dwsixyearreview/potential-revisions-microbial-and-disinfectionbyproducts-rules.
This consultation process will be conducted consistent with the EPA Policy on Consultation with Indian Tribes (https://www.epa.gov/tribal/epa-policy-consultation-indian-tribes) and the Guidance for Discussing Tribal Treaty or Similar Rights (https://www.epa.gov/tribal/epa-policy-consultation-indiantribes-guidance-discussing-tribal-treaty-or-similar-rights). The agency invites you and your designated consultation representative(s) to participate in this process to discuss information related to proposed revisions to the National Primary Drinking Water Regulations for Microbial and Disinfection Byproducts, including treaty or similar rights, Indigenous knowledge, and sacred sites. The EPA’s anticipated timeline for the consultation period is expected to extend from November 1, 2024 to December 31, 2024.
Enclosed is a consultation plan that includes a description of the action under consultation, a timeline for the consultation period, and information on how you can provide input on this action. This information is also available on the EPA’s Tribal Consultation Opportunities Tracking System (TCOTS) at https://tcots.epa.gov.
I look forward to hearing from you on this important matter.
Sincerely,
Jennifer L. McLain, Director
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