The water table is normally very high, with peat bogs as a common occurrence. Glacial deposits in the northern and southern part of the watershed are mainly organic deposits of peat and muck in wetland areas. The central part of the watershed is primarily till, made up of clay, silt, sand, gravel, cobble and boulders. Soils in the northern portion of the watershed are mainly organic soils. The central watershed is a large area of black, limey, clay soils.
Sandy soils make up the southern part of the watershed.
A large portion of the northeastern part of the watershed is an area of extensive wetland drainage. A buried aquifer underlies an area along the Roseau River in the northeastern portion of the watershed. Ground water supplies are plentiful in the watershed. Recharge occurs in the higher sandy soils in the southern portion of the watershed, and discharge occurs in lower areas and to streams. The following charts show the assessments of water quality of streams in the watershed.