Big Muddy River Here the outline of the Wisconsinan Era lake bed is evident in what were the northern reaches of the ancient lake, where the lake bed was only a few hundred feet wide. The steep Illinoian hills are suddenly truncated where they meet the flat bottom of the Wisconsinan Era lake bed. Here the tributaries of the Big Muddy are tiny, intermittent streams, meandering though these narrow valleys at the headwaters. The Big Muddy basin contains a significant portion of the planet's coal reserves. Most of this is hidden under its deep mud. At a few places the river has eroded
Big Wood River receives the tributary streams of Warm Springs Creek and Trail Creek. Below Ketchum, it is joined by the East Fork Wood River at Gimlet before passing by the small cities of Hailey and Bellevue. Continuing south, the river enters the Wood River Valley, the northern part of Magic Valley, after which it flows into Magic Reservoir. A tributary stream, Camas Creek, joins the river in Magic Reservoir. Below Magic Dam, the Big Wood River enters Lincoln County, passing by many lava beds and irrigation canals before entering Gooding County. Just west of Gooding, the Big Wood River joins the Little