The Bark River originates at Bark Lake in Washington County, Wisconsin, flowing approximately 67 miles southwestward through Washington, Waukesha, and Jefferson counties before joining the Rock River near Fort Atkinson. This tributary drains portions of the Kettle Moraine region, creating a river system that transitions dramatically from clear, spring-fed headwaters through suburban landscapes to agricultural bottomlands. The upper sections near Delafield and Hartland showcase the river's most appealing characteristics: crystal-clear water flowing over sand and gravel bottoms, intermittent riffles, and Class I rapids where the gradient increases. The Bark passes through several lakes in Waukesha County, including the Nemahbin Lakes and Lake Nagawicka, creating a unique river-lake-river paddling experience. Water clarity in these upper reaches is exceptional, with visibility often exceeding several feet even during moderate flows. From Merton to Delafield, paddlers navigate through suburban Milwaukee's western fringe, where the river maintains surprising wildness despite nearby development. The stretch from Rome Dam to Cushman Road represents the river's paddling gem—clear, moderately paced water with pleasant riffles and minimal development. Downstream from Highway 106, the Bark transforms into a slower, muddier floodplain river as it approaches its confluence with the Rock River.

Paddling difficulty ranges from beginner-friendly flatwater in the lower sections to intermediate maneuvering required in the upper reaches, where low-clearance farm bridges, occasional logjams, and shallow rocky sections demand attention. The Rome gauge typically reads between 40-250 cfs, with optimal conditions occurring between 50-100 cfs for the clearer upstream sections. Spring and early summer provide the most reliable water levels, though the river remains generally navigable year-round except during extreme drought.

Wildlife includes great blue herons, wood ducks, sandhill cranes, bald eagles, muskrats, and various fish species including bass and northern pike. The clear upper sections support diverse aquatic vegetation and healthy fish populations.

Key access points include Rome Dam, Cushman Road, Highway 106, Delafield Post Office, Sugar Island Road (Lower Nemahbin Lake), Highway 67 in Dousman, and Burnt Village County Park near Fort Atkinson. The Glacial Drumlin State Trail parallels portions of the river, enabling convenient bike shuttles.

Historically, the river powered mills at several locations, with remnants visible at Rome and other sites. William Haumerson operated a brick manufacturing company that shaped the river's lower reaches in the late 1800s.

Paddlers should portage the low-head dam at Sawyer Road and navigate carefully around numerous low-clearance pedestrian and farm bridges between Delafield and Highway 67. The river floods periodically, creating challenging conditions in the lower floodplain sections.