| Location | Liberty / Toole counties, Montana, United States |
|---|---|
| Coords | 48°19′20″N 111°05′48″W |
| Inflow | Marias River |
| Outflow | Marias River |
| Basin countries | United States |
| Area | 14,842 acres (60.06 km2) |
| Elevation | 3,025 ft (922 m) |
Lake Elwell (a.k.a. Tiber Reservoir) is a reservoir in north central Montana. The reservoir was created by the damming of the Marias River at the Tiber Dam. Lake Elwell was named for Judge Charles B. Elwell (1888–1974), former director of the Montana Reclamation Association.[1]