Montana Dams
2,990 dams tracked by the National Inventory of Dams
Total Dams
2,990
High Hazard
188
6.3%
Poor / Unsatisfactory
132
Average Age
74 yrs
Hazard Classification
High188 (6.3%)
Significant193 (6.5%)
Low2,606 (87.2%)
Condition Assessment
Satisfactory113 (3.8%)
Fair44 (1.5%)
Poor / Unsatisfactory132 (4.4%)
Not Rated2,701 (90.3%)
Federal
278
State
151
Local
84
Private
2,466
Tallest Dams
- Yankee Doodle Tailings Dam570 ft
- Hungry Horse Dam564 ft
- Libby Dam422 ft
- Noxon Rapids260 ft
- Fort Peck Dam256 ft
High Hazard Dams
- Yankee Doodle Tailings DamHigh
- Hungry Horse DamHigh
- Libby DamHigh
- Noxon RapidsHigh
- Fort Peck DamHigh
Poor Condition Dams
All Dams in Montana
Showing 2051–2075 of 2,990
| Dam Name | Height (ft) | Year | Hazard | Condition |
|---|---|---|---|---|
| Olson, Oscar (Meagher) Meagher County | 40 | 1959 | High | Satisfactory |
| Olson (Prairie) Prairie County | 30 | 1963 | Low | Not Rated |
| Olson (Richland) Richland County | 30 | 1958 | Significant | Not Rated |
| Omicron Glacier County | 15 | 1950 | Low | Not Rated |
| One D-4 Ranch Carter County | 20 | 1952 | Low | Not Rated |
| Onion Head Meagher County | 29 | 1955 | Low | Not Rated |
| Onwatt Phillips County | 20 | 1932 | Low | Not Rated |
| Orcutt Ranch Company Pondera County | 20 | 1948 | Low | Not Rated |
| Ork Phillips County | 25 | 1949 | Low | Not Rated |
| Orville #1 Hill County | 30 | 1937 | Low | Not Rated |
| Oscar #1 Fallon County | 12 | 1959 | Low | Not Rated |
| Oscar #6 Fallon County | 20 | 1964 | Low | Not Rated |
| Oset #1 Musselshell County | 30 | 1945 | Low | Not Rated |
| Oster Blaine County | 15 | 1950 | Low | Not Rated |
| Osterized Chouteau County | 11 | 1908 | Low | Not Rated |
| Ostle Teton County | 12 | 1910 | Low | Not Rated |
| Ostleer Dam Petroleum County | 12 | — | Low | Not Rated |
| Ostrich Egg Hill County | 20 | 1950 | Low | Not Rated |
| Otilalda Pondera County | 15 | 1960 | Low | Not Rated |
| Otto Silvan Chouteau County | 9 | 1964 | Low | Not Rated |
| Ottun #3 Big Horn County | 18 | 1950 | Low | Not Rated |
| Ottun #5 Big Horn County | 15 | 1963 | Low | Not Rated |
| Ottun #6 Big Horn County | 16 | 1965 | Low | Not Rated |
| Ottun #8 Big Horn County | 12 | 1965 | Low | Not Rated |
| Ottun #9 Big Horn County | 15 | 1950 | Low | Not Rated |
Data sourced from the National Inventory of Dams (NID). Hazard classification reflects potential consequences of failure, not the likelihood of failure.