Rainbow Falls | |
---|---|
Location | Cascade County, Montana, USA |
Type | Block |
Total height | 47 feet |
Number of drops | 1 |
Total width | 1,320 feet |
Coordinates: 47°32′00″N 111°12′20″W / 47.53333°N 111.20556°W
Rainbow Falls (originally "Handsome Falls") is a waterfall on the Missouri River in Great Falls, Montana, just upstream from Crooked Falls and downstream from Colter Falls and Rainbow Dam. It is 47 feet (14m) high and 1,320 feet (402.3m) wide. The waterfall is part of the five Great Falls of the Missouri. The river spills over a sheer ledge of sandstone in the Kootenai Formation, forming the falls. The falls used to flow with a great deal of force year-round. In 1914 the river shortly upstream was dammed for hydroelectric power by the Rainbow Dam, which forms a run-of-the-river reservoir. As a result, the falls can almost totally dry up in the summer with only a few narrow strips of water trickling down its face. A railroad bridge crosses the river directly above the falls.
Rainbow Falls varies widely - whether it is in full flow in the spring, or greatly diminished by the autumn. In peak flow in the springtime, the falls is much like its original form - especially on the right side where the outlet works of the dam are located, and on the left side where the main spillway structure is positioned. The center section of the dam, which is also a spillway structure, only functions when the flow above the reservoir is too great. The left side of the falls is more heavily eroded than the right side, and sits a little farther upstream. Expansive and arid hills rise above the canyon on each bank. Below the falls is a long, narrow plunge pool, and a series of gravel bars.