Big Muddy River The Big Muddy was not covered by the Wisconsin Glacier, about 70,000 to 10,000 years before present. However, during the melting of that glacier, the level of the Mississippi River was much higher. Water backed up into the Big Muddy Basin, forming a lake much like the artificial Rend Lake but covering a larger area. The ancient lake silted in, forming a flat bottom. After the melting of the Wisconsinan glacier, the level of the Mississippi dropped, allowing the lake to drain. A new channel formed within the old lake bed. This channel meandered in the flat bottom of the
Muddy River (Nevada) abandoned the area in 1871. Many of the LDS people returned to the area in the 1880s and it currently has a substantial Mormon population. Muddy River (Nevada) The Muddy River, formerly known as the Moapa River, is a short river located in Clark County, in southern Nevada, United States. It is in the Mojave Desert, approximately north of Las Vegas. The Muddy River is approximately long. It begins as a series of thermal springs in the Moapa Valley before continuing on its course to Lake Mead, where it drains into the northern arm of the lake near Overton, Nevada.