Rainbow Falls (Missouri River)

Rainbow Falls was a significant waterfall located on the Missouri River in present-day Montana, United States. Discovered and named by the Lewis and Clark Expedition in 1805, it was the smallest of five major waterfalls encountered on that stretch of the river, collectively known as the Great Falls of the Missouri.

Rainbow Falls was distinguished by the constant rainbows formed by the mist rising from the falling water, particularly when viewed from certain angles and under specific lighting conditions. The falls were located relatively close to the much larger Great Falls.

In the early 20th century, the falls were submerged due to the construction of Ryan Dam, which impounded the Missouri River to create a reservoir known as Rainbow Lake. As a result, Rainbow Falls no longer exists as a natural waterfall. Its location is now underwater, part of the reservoir system managed for hydroelectric power generation. While the name "Rainbow Falls" persists, it primarily refers to the general area now covered by the lake and dam. The legacy of Rainbow Falls remains through historical accounts, maps, and its association with the Lewis and Clark Expedition.