UNITED STATES COURT OF APPEALS FOR THE NINTH CIRCUIT

UPPER MISSOURI WATERKEEPER, No. 19-35898 Plaintiff-Appellee, D.C. No. v. 4:16-cv-00052- BMM U.S. ENVIRONMENTAL PROTECTION AGENCY; MICHAEL REGAN, * Administrator, United States Environmental Protection Agency, Defendants,

TREASURE STATE RESOURCES ASSOCIATION OF MONTANA; STATE OF MONTANA DEPARTMENT OF ENVIRONMENTAL QUALITY, Intervenor-Defendants,

and

NATIONAL ASSOCIATION OF CLEAN WATER AGENCIES; THE MONTANA LEAGUE OF CITIES AND TOWNS, Intervenor-Defendants-Appellants.

* Michael Regan has been automatically substituted for former Administrator Andrew Wheeler. Fed. R. App. P. 43(c)(2). 2 UPPER MISSOURI WATERKEEPER V. USEPA

UPPER MISSOURI WATERKEEPER, No. 19-35899 Plaintiff-Appellee, D.C. No. v. 4:16-cv-00052- BMM U.S. ENVIRONMENTAL PROTECTION AGENCY; MICHAEL REGAN, Administrator, United States Environmental Protection Agency, Defendants, NATIONAL ASSOCIATION OF CLEAN WATER AGENCIES; THE MONTANA LEAGUE OF CITIES AND TOWNS; STATE OF MONTANA DEPARTMENT OF ENVIRONMENTAL QUALITY, Intervenor-Defendants,

and TREASURE STATE RESOURCES ASSOCIATION OF MONTANA, Intervenor-Defendant-Appellant. UPPER MISSOURI WATERKEEPER V. USEPA 3

UPPER MISSOURI WATERKEEPER, No. 20-35135 Plaintiff-Appellee, D.C. No. v. 4:16-cv-00052- BMM U.S. ENVIRONMENTAL PROTECTION AGENCY; MICHAEL REGAN, Administrator, United States Environmental Protection Agency, Defendants, NATIONAL ASSOCIATION OF CLEAN WATER AGENCIES; THE MONTANA LEAGUE OF CITIES AND TOWNS; TREASURE STATE RESOURCES ASSOCIATION OF MONTANA, Intervenor-Defendants,

and STATE OF MONTANA DEPARTMENT OF ENVIRONMENTAL QUALITY, Intervenor-Defendant-Appellant. 4 UPPER MISSOURI WATERKEEPER V. USEPA

UPPER MISSOURI WATERKEEPER, No. 20-35136 Plaintiff-Appellee, D.C. No. v. 4:16-cv-00052- BMM U.S. ENVIRONMENTAL PROTECTION AGENCY; MICHAEL REGAN, Administrator, United States Environmental Protection Agency, Defendants-Appellants,

and NATIONAL ASSOCIATION OF CLEAN WATER AGENCIES; THE MONTANA LEAGUE OF CITIES AND TOWNS; TREASURE STATE RESOURCES ASSOCIATION OF MONTANA; STATE OF MONTANA DEPARTMENT OF ENVIRONMENTAL QUALITY, Intervenor-Defendants. UPPER MISSOURI WATERKEEPER V. USEPA 5

UPPER MISSOURI WATERKEEPER, No. 20-35137 Plaintiff-Appellant, D.C. No. v. 4:16-cv-00052- BMM U.S. ENVIRONMENTAL PROTECTION AGENCY; MICHAEL REGAN, Administrator, United States OPINION Environmental Protection Agency, Defendants-Appellees, NATIONAL ASSOCIATION OF CLEAN WATER AGENCIES; THE MONTANA LEAGUE OF CITIES AND TOWNS; TREASURE STATE RESOURCES ASSOCIATION OF MONTANA; STATE OF MONTANA DEPARTMENT OF ENVIRONMENTAL QUALITY, Intervenor-Defendants-Appellees.

Appeals from the United States District Court for the District of Montana Brian M. Morris, Chief District Judge, Presiding

Argued and Submitted March 4, 2021 Portland, Oregon

Filed October 6, 2021 6