This IBA is on the Brule River State Forest and encompasses the Brule Glacial Spillway State Natural Area. The site lies along the divide between the watersheds of the Gulf of Mexico and the Atlantic Ocean, with wet peatlands holding water that flows both to the Great Lakes and the Mississippi River. This unique feature was formed when melting glacial water needed a place to flow. To the north was ice, so the water flowed south to the Gulf of Mexico. As the glacier melted and the level of the Lake Superior fell, the outlet shifted to the east. At the Brule Bog, just north of Solon Springs, a high point permitted the water to flow in two different directions over a very short distance (Jerrard 1956: p. 7-8, 13). The surrounding sands absorb water that eventually comes to the surface in springs or seeps along nearly the full length of the spillway. Primary vegetative cover types include alder thickets, forested conifer wetlands, sedge meadow, open bog, white cedar swamp, black ash swamp, mature conifer upland forest, and spruce-fir. Smaller patches of aspen, marsh, barrens, and jack pine exist. The location also harbors numerous other rare features including wolves, orchids, and boreal butterflies that are rare for Wisconsin (WDNR 2007).
This IBA harbors one of the most diverse bird faunas per unit area of any site in the state. Swamp conifer, shrub swamp, and boreal species are especially well represented. Rare and high priority species breeding here include Black-backed Woodpecker, Olive-sided Flycatcher, Cape May Warbler, and Connecticut Warbler. Boreal Chickadees have been observed in the area (C. Matula pers. comm.. 2007).
As part of the Brule River State Forest and as a State Natural Area, this site is protected from most human impacts. However, the portions of the spillway where black ash occurs could be devastated if they become infested by the emerald ash borer (Agrilus planipennis), which has been found in Illinois and Michigan?s Upper Peninsula. The importance of this area to state bird populations, especially boreal species, is not well understood and deserves more study.