Siskiwit River (Wisconsin)

Project Status: modeling is complete

River Basin Characteristics
The Siskiwit River is a tributary to Lake Superior and discharges through a federally maintained channel and shallow-draft harbor in the City of Cornucopia, Wisconsin. The harbor is primarily used for recreational purposes and commercial fishing. The Siskiwit River watershed covers 26.3 square miles of land in northern Wisconsin in Bayfield County.

Land use within the basin is predominantly forested and the population density within the watershed is very low. Watershed soils are a mixture of clay loam, silt loam, and sand, with the headwater of the watershed cutting through sand, muck, and decomposed plant material. The Siskiwit River Watershed has a high density of logging roads, which is thought to be a significant contributor of sediment due to the exposed earth and flow path for overland flow carrying sediments to adjacent streams. Other likely sources of sediment include areas where heavy logging and clear cutting has occurred, headcutting of steep valley walls in the upper reaches, lateral migration and bank erosion along the river, and a high density of beaver dams and beaver dam failures which can contribute to active fluvial processes in the watershed.

Dredging occurs in Cornucopia Harbor for navigation purposes but also to maintain access for commercial fishing and recreational uses of the harbor. In recent years, the harbor has been dredged approximately once every four years, with an average of 7,300 cubic yards per dredge.

		Dredging is required to maintain access to recreational boat docks and commercial fishing slips in Cornucopia Harbor Watershed is 90% forested Siskiwit River Watershed has a high density of logging roads and areas where clear cutting has occurred Steep valley walls, river bank erosion, and beaver dams are also contributors of sediment

Modeling Approach
Through the collection of sediment source information, the Corps developed a sediment budget which determines the magnitude of sediment sources for each potential source of sediment. A Geographic Information System (GIS) tool in a format compatible with Google Earth (TM) has been developed to inventory these sediment sources. This spatial database includes locations of all noted sediment sources with pictures, bed material, and a rating of stability and intensity of erosion. This sediment inventory may be used as a baseline condition for measuring results of proposed activities such as beaver management or sediment traps.

Development of the Google Earth Inventory tool and recommendations were completed in November 2010, along with a training workshop for state and local partners to learn to utilize the tool for various planning scenarios.

Use and Applications
The Corps has developed a tool that can be used by local stakeholders to monitor the condition of various features in the watershed. This Google Earth spatial database noted features such as eroding banks, incised channels,
beaver dams, log jams, among others in several significant reaches. This spatial database can be compared to future data collected to determine conditions of these features over time. It can also be used to identify features of concern where restoration projects may be able to reduce sediment loads, such as identifying river banks that are contributing significant sediment to the Siskiwit River or citing the locations of proposed sediment traps.

Project Partners
Siskiwit Bay Marina

Town of Bell Marina

Halvorson's Fisheries

Red Cliff Tribe Fisheries

USCG

Wisconsin Department of Natural Resources

U.S. Geological Survey

For more information - or to obtain digital data for advanced modeling purposes - contact:

James P. Selegean, P.E., Ph.D.
Great Lakes Hydraulics and Hydrology Office
U.S. Army Corps of Engineers
Detroit District
477 Michigan Avenue
Detroit, MI 48226
Office: (313) 226-6791
Fax: (313) 226-2398
James.P.Selegean@usace.army.mil

Calvin T. Creech, PE, LEED AP, CFM

Great Lakes Hydraulics and Hydrology Office
U.S. Army Corps of Engineers
Detroit District
477 Michigan Avenue
Detroit, MI 48226
Office: (313) 226-3002

Calvin.T.Creech@usace.army.mil