MT HB441

Permits issued before a final water rights decree in a basin are provisional and subject to that decree; the department must notify water rights owners within 60 days of a final decree (or by January 31, 2026 for decrees issued before January 1, 2026)

Existing water rights holders may petition within 180 days to reduce, modify, or revoke provisional permits if water was not legally available at the time of issuance based on the final decree findings

Petitioners must prove by preponderance of evidence that modification is necessary to protect their decreed water rights; the department must act on petitions within 120 days of the response period

Changes in appropriation rights must be verified against the final decree to ensure elements match the adjudicated water right or any modifications to provisional permits

The Secretary of State must send a copy of the act to each federally recognized tribal government in Montana