| Lake McKenzie | |
|---|---|
  Lake McKenzie | |
| Location | McLean, Mercer, and Dunn, Counties, North Dakota |
| Coordinates | 47°31′43″N 101°24′22″W / 47.528614°N 101.406182°W |
| Lake type | Glacial lake (former) |
| Primary inflows | Laurentide Ice Sheet |
| Primary outflows | Over the divide to the Yellowstone River or along the face of the Ice sheet. |
| Basin countries | United States |
| Max. length | about 140 miles (230 km) |
| Max. width | 40 miles (64 km) |
| Surface area | varied |
| Surface elevation | 1,940 m (6,360 ft) |
| References | [1] |
Before the Pleistocene Ice Age, circa two million years before present (YBP), the rivers in North, South Dakota and eastern Montana drained northeast into Canada and then into Hudson Bay.[2] The Keewatin Lobe of the continental ice sheet, block the flow of water northward and impounded it along the ice front. Lakes formed, until the waters could find a new way to drain. Initially, the north flowing rivers followed the front of the glacier eastward and into a valley that passed between Garrison and Riverdale, to the Turtle Lake area, and on into Sheridan County. This is known as the preglacial McClean River.[2] This valley became blocked by the glacier and the glacial lake identified as Lake McKenzie formed. Eventually, water level rose to crest the south ridge a point near Riverdale — at the site of the modern Garrison Dam and a diversion trench was cut. The modern Missouri River follows this pathway.[2]
