Montana water rights

406,496 rights at 550,563 points of diversion in 56 counties · fetched October 8, 2026 from Montana DNRC, Water Resources Division

Open Montana on the map How Montana water rights work

Groundwater: 223,949
Surface water: 182,481
Other source: 66

Montana at a glance

Doctrine: Prior appropriation
Dividing line: July 1, 1973 (Montana Water Use Act)
Adjudication court: Montana Water Court, statewide
Small groundwater use: 35 gpm or less, not over 10 acre-feet a year
Sale paperwork: Water Right Ownership Update (Form 608)
Nonuse: 10 successive years raises a presumption of abandonment

Counties

Counties come from where each right's first point of diversion falls on Census county lines.

Oldest priority dates in Montana

Seniority is weighed among rights on the same stream system, so this is where the oldest records are rather than a statewide ranking.

Priority date · senior to junior

Before 1880
1880–1899
1900–1919
1920–1949
1950–1972
1973–1999
2000 and later
No priority date