Melissa Hamer: A year loaded with environmental regulatory changes

If you felt like environmental compliance was a game of regulatory whack-a-mole this year, you’re not alone.

Between Supreme Court rewrites of familiar statutes, a moving target for PFAS obligations, extended methane deadlines, and Indiana’s new stormwater and water-pipeline rules, our regulated community spent 2025 chasing certainty.

What follows is a quick tour of this year’s highlights, and why planning, permitting, and litigation strategies all had to flex.

Clean Water Act

In March, the Supreme Court held that not all “limitations” under the CWA’s effluent-limitations provision must qualify as “effluent” limitations. City & Cnty. of San Francisco, California v. Envtl. Prot. Agency, 604 U.S. 334, 344-346 (2025).

In plain English, our Supreme Court said an agency can’t write a permit that says “thou shalt never contribute to a water quality standard exceedance” and then blame the permittee for everything even upstream, not just what they discharge. This change could be helpful to look at what a permittee can control rather than the ambient condition of shared waters prior to discharge.

Clean Air Act

On June 18, the Court, in a consolidated case, issued two venue rulings that shape how and where EPA actions are litigated. First, for EPA v. Calumet Shreveport Refining, the Court confirmed that certain EPA actions, even if locally applicable, belong in the D.C. Circuit when EPA properly finds and publishes that the action is based on a determination of “nationwide scope or effect.”

The Court put forth a two-step inquiry for determining venue. Envtl. Prot. Agency v. Calumet Shreveport Ref., L.L.C., 605 U.S. 609, 615 (2025). Second, in Oklahoma et al. v. EPA, the Court held that individual State Implementation Plan disapprovals are locally or regionally applicable actions reviewable in regional circuits, even if bundled in an omnibus Federal Register notice. Id., at 620. So, venue fights are now a threshold strategy call, not an afterthought, since some program decisions could be litigated in more than one venue with different odds of success.

National Environmental Protection Act

In May, the Supreme Court unanimously reversed the D.C. Circuit’s demand for expansive “upstream” and “downstream” analysis in the Uinta Basin Railway case. Seven County Infrastructure Coalition v. Eagle County held that NEPA doesn’t force agencies to chase the effects of separate projects, especially those outside their jurisdiction. 605 U.S. 168, 189-191 (2025). It also says that the potential for projects only related in time or use, related through a but-for causal relationship, or that are potentially foreseeable just isn’t enough to demand more analysis.

But the ultimate question here was not whether the Environmental Impact Statement in and of itself was inadequate, but whether appellate review of the reviewing board’s final decision was reasonable. So, while 2024 saw the overturning of Chevron deference, the Court here emphasized the high level of deference due to the NEPA-reviewing agency in judicial review.

Keep in mind that NEPA imposes no substantive constraints on a decision to build, fund, or approve a proposed project. An EIS “is only one input into an agency’s decision and does not itself require any particular substantive outcome,” such that “the adequacy of an EIS is relevant only to the question of whether an agency’s final decision … was reasonably explained.” Id., at 179-80.

PFAS

If PFAS felt like regulatory jazz this year, that’s because EPA has played variations on a theme of delay. The final national primary drinking water regulation (NPDWR) for six PFAS Maximum Contaminant Levels (MCLs) took effect in June 2024, including for PFOA and PFOS. PFAS NPDWR, 89 FR 32,532-01 (Apr. 26, 2024).

But in May 2025, EPA said it would maintain those two but extend compliance deadlines and reconsider determinations for PFHxS, PFNA, and HFPO-DA (GenX), including the Hazard Index approach. Operators (and bond counsel) now are trying to time capital programs to evolving deadlines and constituents. Press Release, U.S. EPA, EPA Announces It Will Keep MCLs for PFOA, PFOS (May 14, 2025)

In May, EPA issued an interim final rule delaying the reporting window for Toxic Substances Control Act (TSCA) § 8(a)(7) one-time reporting and signaled it might reopen aspects of the 2023 rule. Then in November, EPA proposed certain exemptions along with timeline adjustments.

Many companies that built data systems for a “no-exemptions” world now must decide whether to keep collecting under a broad standard or to pivot to narrower proposed categories, with an eye to future changes and potential litigation. PFAS Data Reporting and Recordkeeping Under (DRRU) the TSCA; Change to Submission Period, 90 FR 20236-01, 90 Fed. Reg. 20,236 (May 13, 2025). PFAS DRRU TSCA; Revision to Regulation, 90 FR 50923-01 (Nov. 13, 2025). The net effect is that TSCA plans that were locked-in for Q1 became revise-as-you-go by Q4.

Oil and gas

For owners/operators under EPA’s New Source Performance Standards 40 C.F.R. pt. 60, subpart OOOOc for new crude oil and natural gas facilities since Dec. 2022, and Emissions Guidelines for existing facilities under subpart OOOOc, EPA first issued an interim final rule in July 2025 extending both the multiple compliance deadlines and the state-plan submittal deadline and also delaying the Super-Emitter Program.

In December, EPA finalized the extension and set certain monitoring/reporting dates. Oil and Natural Gas Sector Climate Review: Extension of Deadlines in Standards of Performance for New, Reconstructed and Modified Sources and Emissions Guidelines for Existing Sources, 90 FR 55671-01 (Dec. 3, 2025). Adjust your calendars accordingly.

Indiana stormwater preemption

Indiana’s new HEA 1037 (Pub. L. 150) says local units may not adopt stormwater laws, rules, ordinances or regulations more stringent than IDEM’s Construction Stormwater General Permit (CSGP), that any such provision is void, and a unit must discharge its duties under the state program.

The May 1 law adding Ind. Code §36-1-3-14 also authorizes warnings and stop-work orders for potential and ongoing violations. Love it or not, designs and enforcement now meet a single statewide baseline instead of having local rule. (Ind. Gen. Assemb., 2025 Reg. Sess., H.B. 1037 (Public Law 150). Make sure you check bid specs and local manuals for anything exceeding a CSGP, including financial assurances, post-construction drainage reports, dust/sediment controls, etc.

Indiana water pipelines

This new law matters for utilities, large economic development and communities wary of interbasin water transfers, such as for the Lebanon LEAP development. The idea here is to make big water moves happen only with statewide eyes on reliability, hydrology and rate impacts.

Indiana’s SEA 4 (Pub. L. 99), effective July 1, 2025, does three big things: defines “long-haul water pipelines” and requires that a Certificate of Public Convenience and Necessity be issued by the IURC before construction; triggers transfer permits for qualifying interbasin transfers through the Indiana DNR, evaluating hydrologic sustainability and the “public interest;” and adds notice and recovery mechanisms (with some cost recovery) and clarifies agency roles.

The through-line for 2025 is simple: trying to manage uncertainty. For 2026, calendar your deadlines and extensions (and extensions to the extensions), write permits the statute actually authorizes (hopefully), litigate where it counts and when in doubt, add one more footnote.•

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Melissa A. Hamer is an attorney with Kroger Gardis & Regas LLP. Opinions expressed are those of the author.