The surficial geology of the watershed is composed of primarily sand and gravel outwash and glacial till. These glacial deposits vary in both permeability and thickness to bedrock. Within these deposits are unconfined (water table) aquifers of sufficient waterbearing capacity to provide municipal and private water. These water table aquifers are vulnerable to contamination since they are relatively close to the land surface. Contaminants have a relatively direct access to these aquifers through minimal infiltration. Recharge areas for drift aquifers are those locations where water can reach the water table through percolation of water through soil and drift materials.
The sequence of major aquifers underlying the District include:
- Glacial sand and gravel deposits.
- St. Peter sandstones.
- Shakopee-Oneota dolomites (Prairie du Chien).
- Jordan sandstones.
- Franconia and Galesville sandstones.
- Mt. Simon-Hinckley sandstones.