The Trout River is a slow, warm, alkaline stream with clear water of high fertility. Flowing west from Trout Lake, it eventually joins the Manitowish River just west of the forest boundary. Averaging 30 feet in width and with a maximum depth of 3 feet, the river supports numerous rare animals including three fish, a dragonfy, and a freshwater mussel. The stream bottom is primarily sand and gravel where the current is moderate to fast as compared to the muck substrate that is found on slower stretches. Patches of aquatic vegetation are common in the lower reaches. Trout River is owned by the DNR and was designated a State Natural Area in 2007.
