A variety of glacial landforms (moraines, till plains, drumlin fields and outwash plains) characterized the 3,890-square mile Mississippi and Sauk Rivers watershed.
Underlying the glacial drift are Cambrian and Precambrian sedimentary rocks in the southeastern part of the watershed and Precambrian igneous and metamorphic rocks elsewhere.
Surface drainage is entirely to the Mississippi River, the largest tributary being the Sauk River, which drains an area of about 970 square miles. The Mississippi follows a regional topographic low and transects the watershed from north to south. Greatest relief is in the morainal area in the west-central part of the watershed. The outwash plain in the southeastern part of the watershed and associated terrace deposits along the Mississippi River form a large area of relatively low relief. Details of topography are shown on 7 ½ and 15’ U.S. Geological Survey quadrangle maps, as indexed.
Agriculture is the major economic activity. Small communities are scattered throughout the watershed; most larger municipalities and related development are concentrated along the Mississippi River.
Lakes and streams offer good recreational opportunities.
