Regulated Entities Rebut Adequate-Representation Presumption by Raising Statutory Arguments the Agency Won’t Make

Case: Lucas Cnty. Bd. of Comm'rs v. EPA Court: Court of Appeals for the Sixth Circuit Date: March 9, 2026

I. Introduction

This interlocutory appeal arises from an Administrative Procedure Act (“APA”) suit challenging U.S. EPA’s approval of Ohio EPA’s phosphorus Total Maximum Daily Load (“TMDL”) for the Maumee River system and connected waters feeding Lake Erie’s western basin. Plaintiffs—Lucas County, the City of Toledo, and the Environmental Law & Policy Center—allege the approval was “arbitrary and capricious and contrary to law” under the APA.

The merits of the TMDL were not before the Sixth Circuit. Instead, the key question was procedural: whether two sets of agricultural/industry-aligned proposed intervenors (the “Associations” and the “Maumee Coalition II Association”) could intervene as defendants to defend the TMDL approval. The district court denied both intervention-of-right and permissive intervention. On appeal, the Sixth Circuit split the result: it required intervention for the Associations but affirmed denial for the Coalition.

The opinion is significant because it clarifies how private regulated entities can rebut the Sixth Circuit’s presumption of adequate representation when the government defends its own agency action—particularly when the proposed intervenor wants to defend the action on the ground that certain agency regulatory “requirements” are not actually required by the statute (in the post-Loper Bright landscape).

II. Summary of the Opinion

  • Presumption applies: Because U.S. EPA and both proposed intervenors shared the same “ultimate objective” in the litigation—upholding U.S. EPA’s approval of the Maumee TMDL—the Sixth Circuit applied a presumption that U.S. EPA would adequately represent their interests, consistent with United States v. Michigan.
  • Associations rebutted it: The Associations overcame the presumption by identifying a concrete, case-relevant defense U.S. EPA was unlikely to make: that some of the purported TMDL “requirements” in EPA regulations/guidance are not required by the Clean Water Act’s “single, best meaning” under Loper Bright Enters. v. Raimondo.
  • Coalition did not: The Coalition’s proposed defenses were either outside the scope of the APA claim (misdirected at Ohio EPA/state processes) or were defenses U.S. EPA and Ohio EPA had every incentive and capacity to raise themselves.
  • Permissive intervention denied for Coalition: The district court did not abuse its discretion in concluding Coalition intervention would add complexity and delay without supplying unique, relevant defenses; the opinion highlights amicus participation as the appropriate channel for broader practical/policy concerns.
  • Disposition: Reversed denial of the Associations’ intervention (remand with instructions to grant); affirmed denial for the Coalition.

III. Analysis

A. Precedents Cited

1) Clean Water Act cooperative federalism backdrop

  • Arkansas v. Oklahoma, 503 U.S. 91 (1992): Used to frame the Clean Water Act as a state–federal “partnership,” which contextualizes how TMDLs are created by states but reviewed by U.S. EPA. This background matters because it explains why state agency actions (Ohio EPA’s TMDL drafting) and federal agency actions (U.S. EPA approval) are intertwined, yet only the latter is reviewable under the APA.
  • Env't L. & Pol'y Ctr. v. U.S. EPA, 415 F. Supp. 3d 775 (N.D. Ohio 2019): The opinion recounts the prior litigation history leading to Ohio EPA’s commitment to develop a TMDL and U.S. EPA’s approval timeline, providing the procedural posture for the present APA challenge.

2) Appellate jurisdiction over intervention denials

  • Purnell v. City of Akron, 925 F.2d 941 (6th Cir. 1991): Cited for the collateral-order principle that denials of intervention are immediately appealable.

3) Rule 24 standards and the “adequate representation” presumption

  • Wineries of the Old Mission Peninsula Ass'n v. Township of Peninsula ("WOMP"), 41 F.4th 767 (6th Cir. 2022): Supplies the four-part intervention-of-right test and underscores the “expansive” conception of interest in the Sixth Circuit. Also illustrates that even with a shared outcome, differing concerns can show inadequate representation.
  • United States v. Michigan, 424 F.3d 438 (6th Cir. 2005): The opinion’s anchor for (i) the presumption of adequate representation when parties share the same ultimate objective and (ii) the “scope of the issues in the current phase of litigation” lens for assessing whether an intervenor’s arguments are actually relevant and distinct.
  • Trbovich v. United Mine Workers, 404 U.S. 528 (1972): Used to address the Associations’ claim that Supreme Court precedent forecloses presumptions. The Sixth Circuit reads Trbovich as consistent with a presumption focused on “ultimate objective,” while still recognizing that shared goals can mask divergent litigation approaches.
  • Berger v. North Carolina State Conference of the NAACP, 597 U.S. 179 (2022): Distinguished. The Sixth Circuit notes Berger rejects a presumption when “a duly authorized state agent seeks to intervene to defend a state law,” but does not decide (and expressly leaves open) whether presumptions apply in private-party contexts—thus Sixth Circuit precedent remains binding.
  • Bradley v. Milliken, 828 F.2d 1186 (6th Cir. 1987); Jansen v. City of Cincinnati, 904 F.2d 336 (6th Cir. 1990); Grutter v. Bollinger, 188 F.3d 394 (6th Cir. 1999); Mich. State AFL-CIO v. Miller, 103 F.3d 1240 (6th Cir. 1997); Jordan v. Mich. Conf. of Teamsters Welfare Fund, 207 F.3d 854 (6th Cir. 2000): These cases collectively supply examples of how the presumption can be rebutted—especially where an intervenor can identify particular defenses the existing party may not present because of differing interests or strategic constraints.

4) APA “record review” and limits on post hoc rationalizations

  • Motor Vehicle Mfrs. Ass'n, Inc. v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29 (1983), and DHS v. Regents of the Univ. of Cal., 591 U.S. 1 (2020): Cited by opponents of intervention to argue the Associations’ defenses are impermissible “post hoc rationalizations.” The Sixth Circuit rejects that characterization because the Associations’ argument is not new factual justification outside the record; it is a legal argument about the statutory threshold for validity of approval.

5) Statutory interpretation after Chevron’s demise

  • Loper Bright Enters. v. Raimondo, 603 U.S. 369 (2024): Central to the Associations’ theory. The court treats statutory interpretation as a judicial task governed by the statute’s “single, best meaning,” and accepts that intervenors may argue that regulations/guidance impose requirements beyond that meaning—an argument the agency is unlikely to make about its own rules.

6) Forfeiture vs waiver; preserving arguments

  • Berkshire v. Dahl, 928 F.3d 520 (6th Cir. 2019); Thomas M. Cooley L. Sch. v. Kurzon Strauss, LLP, 759 F.3d 522 (6th Cir. 2014); Hamer v. Neighborhood Hous. Servs. of Chi., 583 U.S. 17 (2017); Cockrun v. Berrien County, 101 F.4th 416 (6th Cir. 2024): The Sixth Circuit uses these to distinguish waiver from forfeiture and to conclude the Associations sufficiently preserved their rebuttal argument through reply and supplemental briefing.

7) Permissive intervention discretion

  • Buck v. Gordon, 959 F.3d 219 (6th Cir. 2020); League of Women Voters of Mich. v. Johnson, 902 F.3d 572 (6th Cir. 2018); Tahfs v. Proctor, 316 F.3d 584 (6th Cir. 2003); Bay Mills Indian Cmty. v. Snyder, 720 F. App'x 754 (6th Cir. 2018): These cases frame the “bounded” discretion and explanation requirement for permissive intervention denials; the district court’s explanation here was deemed sufficient and within discretion.

B. Legal Reasoning

1) The “ultimate objective” triggers the presumption at the litigation-specific level

The Sixth Circuit reaffirmed that the adequate-representation presumption turns on whether the intervenor and an existing party share the same litigation objective. Here, that objective was straightforward: defend U.S. EPA’s approval of the Maumee TMDL. Broader policy differences (e.g., regulated parties generally preferring less stringent nutrient controls, or the agency generally wanting “smooth administration” of the CWA) do not defeat the presumption; they instead may become relevant to whether the presumption is rebutted.

2) Rebuttal framework: distinct, case-relevant arguments + reason the agency likely won’t make them

Synthesizing Jansen, Grutter, Mich. State AFL-CIO, and Michigan, the court effectively articulated a two-part showing sufficient to rebut the presumption: (i) the intervenor has specific arguments within the case’s scope, and (ii) the existing party may not or will not present those arguments because of a conflict of interest or divergent incentives.

Applying that framework, the Associations satisfied both parts: their proposed defense—arguing that certain regulatory/guidance-based “requirements” asserted by Plaintiffs are not required by the Clean Water Act itself—was squarely within the APA “contrary to law” review, and U.S. EPA was unlikely to argue its own regulations are unlawful or unnecessary under the statute.

3) The Associations’ statutory defense is not an impermissible post hoc rationalization

The court drew a sharp line between (a) new factual justifications outside the administrative record (barred as post hoc rationalizations under State Farm and Regents) and (b) legal arguments about what the governing statute requires. The Associations’ defense fell into the latter category: it did not invent new facts to justify approval; it contested Plaintiffs’ legal theory about the statutory baseline for a lawful approval decision.

4) Why the Coalition failed: lack of unique, relevant defenses and presence of Ohio EPA as a defendant

The Coalition’s arguments largely targeted Ohio EPA’s state-law processes (e.g., exhaustion via the Ohio Environmental Review Appeals Commission) or asserted scope-limiting defenses the existing defendants were well-positioned to raise. Critically, Ohio EPA was already an intervenor-defendant, undercutting any claim that Coalition’s interests (permit-holders’ concerns) would go unrepresented, especially where the Coalition could not point to a defense the agencies were unlikely to assert.

5) Appellate court resolves “interest” and “impairment” without remand (Associations)

After finding inadequate representation, the Sixth Circuit declined to remand for the district court to address the remaining Rule 24(a)(2) prongs, emphasizing delay concerns and noting the issues were briefed and reviewed de novo. It then applied the circuit’s “expansive notion” of interest (WOMP) and the “minimal” impairment burden (Mich. State AFL-CIO) to hold that setting aside the TMDL could predictably increase regulatory burdens on members and that adverse precedent could hinder future interests.

C. Impact

  • More intervention by regulated entities in APA defense cases: The opinion provides a clear pathway for regulated parties to intervene on the defense side when they can credibly claim the government will not make certain pro-defense arguments—especially arguments that the agency’s own regulations/guidance exceed statutory requirements.
  • Post-Loper Bright litigation dynamics: With courts not deferring to agency interpretations in the same way, intervenors can play an outsized role by offering “best meaning” statutory arguments that agencies may avoid for institutional reasons (e.g., not wishing to undermine their regulatory programs).
  • Limits remain—scope and redundancy: The Coalition portion underscores that intervention will be denied where defenses are irrelevant to the APA claim’s proper target (federal agency action), or where the defenses are likely to be raised by existing parties—particularly when a state environmental agency is already in the case.
  • Amicus as a pressure valve: The court’s permissive-intervention analysis signals that courts may channel practical, policy, or “impact” narratives into amicus briefing when party intervention would complicate record-bound APA litigation.

IV. Complex Concepts Simplified

  • TMDL (Total Maximum Daily Load): A pollution “budget” for a waterbody—how much of a pollutant (here, phosphorus) can enter while still meeting water-quality standards. It is typically the sum of allocations to point sources (regulated dischargers) and nonpoint sources (diffuse runoff).
  • APA “arbitrary and capricious” review: A court reviews whether the agency’s decision-making was reasonable and lawful, generally confined to the administrative record compiled during the agency process.
  • Intervention of right vs permissive intervention: Under Rule 24(a)(2), the court must allow intervention if the four criteria are met (timeliness, interest, impairment, inadequate representation). Under Rule 24(b), the court may allow intervention but can deny it to avoid undue delay or prejudice.
  • Presumption of adequate representation: In the Sixth Circuit, if an intervenor and an existing party seek the same litigation outcome, courts presume the existing party adequately represents the intervenor—unless rebutted by a showing (often “minimal”) that representation may be inadequate.
  • Post hoc rationalizations: After-the-fact reasons offered in litigation that were not part of the agency’s stated reasoning. Courts generally will not uphold agency action on reasons “nowhere to be found” in the agency record; but courts can consider pure legal arguments about what the statute requires.
  • Waiver vs forfeiture: Waiver is intentional abandonment; forfeiture is failure to raise an issue in time. The Sixth Circuit treated Plaintiffs’ argument as a forfeiture claim and held the Associations preserved the point through reply and supplemental briefing.

V. Conclusion

Lucas Cnty. Bd. of Comm'rs v. EPA reinforces the Sixth Circuit’s presumption of adequate representation when intervenors share the government’s immediate litigation objective, while clarifying a powerful rebuttal route for private regulated entities: identify a concrete, case-relevant legal defense the agency is institutionally unlikely to make—such as a statutory “best meaning” argument that agency regulations or guidance impose requirements the statute does not.

At the same time, the decision draws boundaries: proposed intervenors cannot rely on defenses untethered to the APA’s proper target (federal agency action), cannot justify intervention with redundant arguments the existing defendants will likely raise, and may be relegated to amicus participation when party status would add complexity without materially aiding resolution.