Marathon County is geographically located in what the Wisconsin DNR has named the Central Wisconsin Basin, which is a subset of the entire Wisconsin River corridor located in Central Wisconsin. The Central Wisconsin Basin extends south from the Merrill dam located on the Wisconsin River in Lincoln County to the Castle Rock Flowage Dam in Juneau and Adams Counties. The Central Wisconsin River Basin is comprised of 29 watersheds, 17 of which are all or part in Marathon County. A watershed is an area of land that is drained by a waterway that flows to a lake, reservoir or river. The watershed boundary line is defined as a topographic dividing line from which surface streams flow in two different directions.


The watersheds in Marathon County contain numerous scenic vistas including rock outcroppings and flowages. They are also characterized by diverse agricultural activities throughout the basin. The last glaciers created a network of warm and cold water streams fed by surface and groundwater sources that all connect to the Wisconsin River, except the for two eastern subwatershed in the County. See the Surface Water Data Viewer to view details about the entire basin.


Completed Priority Watershed Programs in Marathon County:

  • Upper Big Eau Pleine Watershed Plan and Final Report
  • Lower Big Eau Pleine Watershed Plan and Final Report
  • Lower Big Rib River Watershed Plan and Final Report
  • Springbrook Watershed Plan and Final Report
  • Yellow River Watershed Plan and Final Report

Other Watershed information: