Big Muddy River Wisconsinan-era lake. This is why the Big Muddy tends to be so muddy. The Big Muddy joins the Mississippi River in Jackson County near the La Rue-Pine Hills Ecological Area and less than south of Grand Tower Island. The Pine Hills are bluffs overlooking the Big Muddy as it flows through La Rue swamp. During the melting of the Wisconsinan glacier, the Mississippi River flood plain was filled with rushing meltwater in summer. During the winter the flow of meltwater was cut off, and the floodplain was a wide stretch of exposed mud. Winter winds created dust storms that covered
Muddy River (Washington) Muddy River Picnic Site, next to the river and to Forest Road 25 in the Gifford Pinchot National Forest. Trails cross the river on its upper reaches. Muddy River originates at about the level on the southeast side of Mount St. Helens in the Cascade Range. The river source is within Mount St. Helens National Volcanic Monument and Gifford Pinchot National Forest. Shoestring Glacier is to the right and East Dome is to the left. Flowing southeast down steep slopes, the river curves sharply to the northeast just beyond the level of the volcano. Here the river crosses Forest Road