This case arises from the ongoing legal battle over harmful algal blooms in Lake Erie, caused by high levels of phosphorus runoff from the Maumee River. In 2023, the Ohio Environmental Protection Agency proposed a Total Maximum Daily Load (TMDL) for phosphorus, which the U.S. Environmental Protection Agency (EPA) approved. While environmental groups sued the EPA claiming the TMDL was insufficient, several agricultural industry groups and the Maumee Coalition II Association sought to intervene as defendants to support the EPA's approval. The district court granted intervention to environmental groups and the Ohio EPA but denied intervention to the agricultural associations and the Maumee Coalition, finding that the EPA would adequately represent their interests and that their arguments were not relevant enough to warrant permissive intervention. The agricultural groups and the Coalition appealed, arguing they needed to be parties to raise specific legal defenses that the EPA might not advance.
The Sixth Circuit, writing for the court, focused on the standard for intervention of right under Federal Rule of Civil Procedure 24(a)(2), specifically the requirement that the applicant's interest be inadequately represented by existing parties. The court applied a presumption of adequate representation when the proposed intervenor shares the same ultimate objective as an existing party, which was the case here as both the EPA and the agricultural associations sought to uphold the TMDL. However, the court held that this presumption can be rebutted if the intervenor shows that the existing party will not make all of their prospective arguments. The agricultural associations demonstrated a conflict of interest because they intended to argue that certain regulatory requirements imposed by the EPA were not actually required by the Clean Water Act itself. The EPA, by contrast, was likely to defend its approval based on the validity of its own regulations. Because the EPA would not argue that its regulations were contrary to law, the agricultural groups had a distinct legal interest that the EPA would not adequately represent. The court distinguished this from the Maumee Coalition's situation, where the proposed defenses were either outside the scope of the case or arguments the EPA and Ohio EPA were already incentivized to raise. Consequently, the court reversed the denial of intervention for the agricultural associations and remanded for the district court to grant their motion, while affirming the denial for the Coalition.
The agricultural industry groups will be granted party status in the underlying litigation, allowing them to present specific legal arguments regarding the statutory interpretation of the Clean Water Act that the EPA might not raise. The Maumee Coalition II Association remains an amicus curiae, unable to participate as a full party. The case is remanded to the district court to formally grant the associations' motion to intervene, after which the court will proceed to the merits of the EPA's TMDL approval.