Montana law

Environmental Laws in Montana.

Montana environmental law combines federal programs (RCRA, CERCLA, CWA, CAA) with state implementation through the Montana Department of Environmental Quality (DEQ). Montana's constitutional right to a clean and healthful environment (Mont. Const. art. II, § 3) is the strongest state environmental-rights provision in the country and supported the Montana Supreme Court's landmark ruling in Held v. Montana (2024) on state climate obligations. Montana administers the Montana Environmental Policy Act (MEPA), Montana Clean Air Act, and Montana Water Quality Act.

Last verified: 2026-04-17

State law

Key Montana Statutes

Right to a Clean and Healthful EnvironmentMont. Const. art. II, § 3; art. IX, § 1

Montana's constitution expressly guarantees this right. The Montana Supreme Court held in Held v. Montana (2024) that the State had violated its constitutional duty by prohibiting consideration of climate impacts in environmental review.

Montana Environmental Policy Act (MEPA)Mont. Code Ann. § 75-1-101 et seq.

Requires environmental review for state agency actions significantly affecting the environment. Analogous to NEPA at the federal level.

Montana Water Quality ActMont. Code Ann. § 75-5-101 et seq.

Authorizes DEQ to administer NPDES permitting and state water-quality standards under delegated CWA authority.

Montana Clean Air ActMont. Code Ann. § 75-2-101 et seq.

Authorizes DEQ to administer air quality programs including permitting, emission standards, and the State Implementation Plan under delegated CAA authority.

Montana Hazardous Waste ActMont. Code Ann. § 75-10-401 et seq.

Regulates hazardous waste generation, transport, treatment, storage, and disposal under delegated RCRA authority.

Metal Mine Reclamation ActMont. Code Ann. § 82-4-301 et seq.

Montana's strong mine-reclamation law requires bonding and permitting for metal mines. Cyanide heap-leach gold mining has been prohibited since 1998.

State law

Official Sources

Montana Department of Environmental Quality U.S. EPA

Not Legal Advice

This page summarizes publicly available statutes and rules for informational purposes only. It does not constitute legal advice, and no attorney-client relationship is created by viewing this content. Laws change — always verify with the primary source or consult a licensed attorney in Montana.

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Environmental Laws in Montana.

Key Montana Statutes

Official Sources

Not Legal Advice

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