2026 Water Look Ahead

We’ve seen some movement from the United States Environmental Protection Agency (U.S. EPA) on several fronts as 2025 came to a close, though at the time of this publication we are still waiting on the Fall 2025 Unified Agenda of Regulatory and Deregulatory Actions (Fall Unified Agenda),. Here’s the latest and what we are looking out for as we move into 2026:

Effluent Limitation Guidelines and Standards for the Steam Electric Power Generating Point Source Category

Motivated by increases in electricity demand due in part to the rise of artificial intelligence (AI) and data centers, on December 31, 2025, U.S. EPA published its final rule extending deadlines under the Effluent Limitation Guidelines (ELG) in the Federal Register. The final rule gives six more years (until December 31, 2031) for facilities to opt into the “early adopter” subcategory, five more years (until December 31, 2034) for facilities to comply with the rule’s zero-discharge limitations for certain waste streams (bottom ash transport wastewater, flue gas desulfurization wastewater, and combustion residual leachate), and additional time for compliance with three zero-discharge limitations for power plants that send wastewater to wastewater treatment plants. Publication in the Federal Register has started the 60-day clock for lawsuits over the measure.

Clean Water Act Hazardous Substances Facility Response Plan Rule

The White House Office of Management and Budget (OMB) completed inter-agency review of two measures regarding the Clean Water Act (CWA) Hazardous Substances Facility Response Plan (FRP) rule including:

• Delay of compliance dates by up to five years (the rule finalized in 2024 currently requires compliance by June 1, 2027) and changes to reflect administrative policy in Executive Order (EO) 14145 “Unleashing American Energy,” and
• A separate advance notice of proposed rulemaking (ANPRM) where U.S. EPA is likely to take comment on future, more substantive revisions to the rule, which may include an increase in threshold quantities, further guidance and/or clarifications around uncertainties including exemptions, consideration of “adverse weather conditions,” and modeling requirements, and changes to FRP requirements.

These actions are consistent with what ALL4 had been hearing through industry groups and sharing with our readers through previous articles. We look forward to seeing these proposals from U.S. EPA and hopefully gaining some clarity around the complexities of this rule.

Perchlorate Drinking Water Standard

OMB has also completed review of U.S. EPA’s proposed drinking water standards for perchlorate. This rule could be consequential in testing U.S. EPA’s authority under the Safe Drinking Water Act (SDWA). U.S. EPA first proposed a rule regulating perchlorate in drinking water in 2019 but then sought to withdraw its 2011 determination to regulate perchlorate under the SDWA and end the rulemaking. In 2023, the U.S. Court of Appeals for the District of Columbia Circuit held that U.S. EPA does not have the authority under the SDWA to revoke previous determinations, requiring the rulemaking to go forward. Drinking water utilities maintain that perchlorate contamination no longer requires regulation, though environmental groups disagree. We’ll be following this proposed standard and potential legal challenges as 2026 unfolds.

Lead and Copper Rule Improvements

The American Waterworks Association’s (AWW) case against the October 2024 Lead and Copper Rule Improvements (LCRI) continues, with briefings scheduled to conclude in January, followed by oral arguments. Checkout ALL4’s most recent blog on the rule; we will continue to keep our readers informed of updates throughout the year. In the meantime, the rule remains in effect with November 1, 2027 deadlines in place.

Waters of the United States

U.S. EPA and the Army Corps of Engineers issued their proposed Waters of the United States (WOTUS) rule back in November 2025 (check out our previous article for more details). The comment period on the proposed rule closed on January 5, 2026, and the rule has already received criticisms from both ends of the spectrum. We’re hearing a lot of speculation and confusion around “wet season” provisions and discontent among environmental groups that the rule does not consider ecological importance or impacts. We will be watching out for changes in the final rule and/or legal challenges once the rule is finalized.

Additional Considerations

• There remains much ado about Per- and polyfluoroalkyl substances (PFAS) in relation to water– watch for a separate lookahead article dedicated to PFAS in a couple of weeks. We are awaiting updates on ELGs for PFAS Manufacturers under the Organic Chemicals, Plastics, and Synthetic Fibers Point Source Category and inclusion of PFAS monitoring requirements in National Pollutant Discharge Elimination System (NPDES) Permit Applications.
• We are also awaiting details on revisions to ELGs and Standards for the Oil and Gas Extraction Category.
• We’re hearing more about microplastics as an emerging contaminant – late last year, multiple states petitioned U.S. EPA to include microplastics in the 2027 renewal of the agency’s Unregulated Contaminant Monitoring Rule (UCMR-6), which is often the first step in determining whether drinking water standards are needed.
• S. EPA’s NPDES Multi-Sector General Permit (MGSP) for Stormwater Discharges Associated with Industrial Activity expires on February 28, 2026. A proposed 2026 MSGP was issued in late 2024 with an extended public comment period ending on May 19, 2025; we expect issuance of the final permit early this year.
• We are tracking state MSGP renewals in several states including Alaska, Wisconsin, Mississippi, Oregon, Texas, Kansas, and Louisiana.

ALL4 has water quality professionals across the country who help clients track and strategically navigate regulatory changes, in addition to supporting with routine permitting and compliance needs. For more information on ALL4’s water service offerings, check out our Water Services page or reach out to our Water Tech Team at water@all4inc.com.

For more information on regulatory updates, check out the recording of our December 2025 Water Regulatory Update Webinar, our Water Regulatory Update Podcast, or reach out to me at lsmith@all4inc.com or 770-999-0269.