Dams in Lewis and Clark County, Montana
30Total Dams
11High Hazard
2Significant
Dam Safety in Lewis and Clark County, Montana
Lewis and Clark County has 30 dams tracked in the National Inventory of Dams. Of these, 11 are classified as high hazard — meaning failure would probably cause loss of human life. Another 2 carry a significant hazard classification. Currently, 1 dams have a condition assessment of poor or unsatisfactory.
The average dam in Lewis and Clark County is 80 years old. The most common purpose is irrigation. The tallest dam is Canyon Ferry Dam at 225 ft.
Explore more: Oldest dams in Montana · Tallest dams · High risk dams · Largest reservoirs
Data note: Hazard potential describes the consequences if a dam failed; it does not predict the likelihood of failure. Inspection, condition, and emergency-plan fields can be incomplete or delayed. Check state dam-safety officials and local emergency managers for official guidance.
| Dam | Hazard | Condition | Height (ft) | Purpose | Year |
|---|---|---|---|---|---|
| Canyon Ferry Dam | High | Not Available | 225 | Flood Risk Reduction | 1954 |
| Hauser Dam | High | Satisfactory | 125 | Hydroelectric | 1911 |
| Holter Dam | High | Satisfactory | 124 | Hydroelectric | 1918 |
| Three Mile Reservoir (l.&c.) | High | Poor | 70 | Irrigation | 1926 |
| Chessman Main Dam | High | Fair | 57 | Water Supply | 1908 |
| Nilan North Dam | High | Satisfactory | 54 | Irrigation | 1951 |
| Nilan East Dam | High | Satisfactory | 51 | Irrigation | 1951 |
| Hinman Dam | High | Not Rated | 34 | Other | 2000 |
| Scott Reservoir | High | Fair | 32 | Water Supply | 1952 |
| Helena Valley Dike | High | Not Available | 30 | Irrigation | 1959 |
| Willow Creek Bor Mt-dike 3 | High | Not Available | 3 | 1941 | |
| Smith Lake | Significant | 15 | Fire Protection, Stock, Or Small Fish Pond | 1954 | |
| Gravelly Range Lake | Significant | 12 | Irrigation | 1964 | |
| J B Long And Company #3 | Low | 34 | Irrigation | 1950 | |
| Soap Creek | Low | 25 | Irrigation | 1950 | |
| Deerborn Reservoir | Low | 20 | Irrigation | 1900 | |
| Curran-barrett #2 | Low | 20 | Irrigation | 1899 | |
| Thompson, Frank | Low | 20 | Irrigation | 1972 | |
| Evans, L. | Low | 20 | Fire Protection, Stock, Or Small Fish Pond | 1961 | |
| J B Long And Company #2 | Low | 20 | Fire Protection, Stock, Or Small Fish Pond | 1930 | |
| Detergent | Low | 15 | Fire Protection, Stock, Or Small Fish Pond | 1956 | |
| Krezelok | Low | 15 | Irrigation | 1945 | |
| Anderson Lake | Low | 15 | Fire Protection, Stock, Or Small Fish Pond | 1956 | |
| Curran-barrett #1 | Low | 15 | Irrigation | 1940 | |
| Flat Milford Colony | Low | 15 | Fire Protection, Stock, Or Small Fish Pond | 1955 | |
| Herrin Lake | Low | 15 | Fire Protection, Stock, Or Small Fish Pond | 1949 | |
| Milford Colony | Low | 15 | Fire Protection, Stock, Or Small Fish Pond | 1963 | |
| Wood Lake Dam | Low | Not Rated | 13 | Other | 1955 |
| Really Red | Low | 10 | Fire Protection, Stock, Or Small Fish Pond | 1953 | |
| Porrini | Low | 10 | Irrigation | 1952 |