Hydrology of the Wisconsin River
The Wisconsin River in both the Upper and Lower Dells is characterized by a sandy bottom with areas of rock ledges. Flow in the river is highly variable and is heavily influenced by the operation of the Castle Rock dam approximately 14 miles upriver from the Upper Dells and the Kilbourn Dam located within the City of Wisconsin Dells. The Kilbourn Dam is the dividing line between the Upper and Lower Dells. Blackhawk Island is located in the Upper Dells. The Kilbourn dam was completed in 1909 to improve navigation and to create hydroelectric power. It is currently owned by Wisconsin Power and Light. The water level in the Upper Dells was raised as much as 16 feet above existing levels. This filled the old channel making Blackhawk Island an island. Both of these dams are operated on a peaking basis.
The river itself is known for its strong swirling currents, which at times of higher water levels can make navigation difficult particularly in the narrows near Devil’s Elbow of Blackhawk Island (most eastern point of the island). Sandbars along the river corridor are the result of deposition of sands by the current. These sandbars change shape and size periodically due to action by the river. During periods of high water, these sandbars are completely submerged. The maximum depth of the river in the Upper Dells is approximately 100 feet and is also the narrowest part of the river at 52 feet in width. This area is located at Devil’s Elbow. Further upstream, near Stand Rock and north of Witches Gultch, the river widens and is shallow and flowage-like for a distance of approximately 4 miles.
Upham Woods is located in the Lower Wisconsin River Basin which drains approximately 4,940 miles of south central and southwestern Wisconsin. Upham Woods is located in the Dell Creek Watershed. Agriculture is the predominant land-use in this watershed. It has also been named a priority watershed and is currently being evaluated to assess impacts to water quality and determine methods to lessen these impacts. Water quality in this portion of the Wisconsin River is generally good.
O’Malley, Dave, et al. “Dells of the Wisconsin River State Natural Area Master Plan and Environmental Assessment.” Dells of the Wisconsin River State Natural Area Master Plan and Environmental Assessment, Wisconsin Dept. of Natural Resources, 1997, pp. 1–53.