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 dam has 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
| Dam | Hazard | Condition | Height (ft) | Purpose | Year |
|---|---|---|---|---|---|
| Canyon Ferry Dam | High | Not assessed | 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 assessed | 34 | Other | 2000 |
| Scott Reservoir | High | Fair | 32 | Water Supply | 1952 |
| Helena Valley Dike | High | Not assessed | 30 | Irrigation | 1959 |
| Willow Creek Bor Mt-dike 3 | High | Not assessed | 3 | 1941 | |
| Smith Lake | Significant | Not assessed | 15 | Fire Protection, Stock, Or Small Fish Pond | 1954 |
| Gravelly Range Lake | Significant | Not assessed | 12 | Irrigation | 1964 |
| J B Long and Company #3 | Low | Not assessed | 34 | Irrigation | 1950 |
| Soap Creek | Low | Not assessed | 25 | Irrigation | 1950 |
| Deerborn Reservoir | Low | Not assessed | 20 | Irrigation | 1900 |
| Curran-barrett #2 | Low | Not assessed | 20 | Irrigation | 1899 |
| Thompson, Frank | Low | Not assessed | 20 | Irrigation | 1972 |
| Evans, L. | Low | Not assessed | 20 | Fire Protection, Stock, Or Small Fish Pond | 1961 |
| J B Long and Company #2 | Low | Not assessed | 20 | Fire Protection, Stock, Or Small Fish Pond | 1930 |
| Detergent | Low | Not assessed | 15 | Fire Protection, Stock, Or Small Fish Pond | 1956 |
| Krezelok | Low | Not assessed | 15 | Irrigation | 1945 |
| Anderson Lake | Low | Not assessed | 15 | Fire Protection, Stock, Or Small Fish Pond | 1956 |
| Curran-barrett #1 | Low | Not assessed | 15 | Irrigation | 1940 |
| Flat Milford Colony | Low | Not assessed | 15 | Fire Protection, Stock, Or Small Fish Pond | 1955 |
| Herrin Lake | Low | Not assessed | 15 | Fire Protection, Stock, Or Small Fish Pond | 1949 |
| Milford Colony | Low | Not assessed | 15 | Fire Protection, Stock, Or Small Fish Pond | 1963 |
| Wood Lake Dam | Low | Not assessed | 13 | Other | 1955 |
| Really Red | Low | Not assessed | 10 | Fire Protection, Stock, Or Small Fish Pond | 1953 |
| Porrini | Low | Not assessed | 10 | Irrigation | 1952 |