On this site, you'll find a compilation of information about the hydrology near the proposed Bridgewater Township Ethanol Plant. The documents linked from this site were generated from county, state and national agencies and from other organizations. The annotations and interpretations of the information are the work of students and faculty in Carleton College Hydrology course, January through March 2007. See "About this website."
Ethanol uses about four gallons of water for each gallon of ethanol produced, so a facilty producing one million gallons of ethanol each year will need four million gallons of water. Read more here about water and ethanol.
Advanced Bioengineering has proposed building an ethanol plant in Bridgewater Township. Local water bodies include the Prairie du Chien - Jordan aquifer, shallow aquifers in surficial materials, the Cannon River, and tributaries to the Cannon River, including Wolf Creek. Read more here about the proposed plant and water locations.
Most water for domestic and industry use comes from the Prairie du Chien and Jordan aquifers, two groundwater sources. The EPA estimates that in the Upper Midwest, per capita use of water in 1990 was 112 gallons/person/day. Read more here about water use in the Northfield area.
Groundwater is stored in pore spaces and fractures in rock formations underground. Aquifers are rock units that have abundant quantities of available water. The water table marks the surface of an unconfined aquifer. The Prairie du Chien and Jordan aquifers are confined aquifers in the Bridgewater Township area. Groundwater pumping may lower the local water table (in an unconfined aquifer) or the piezometric surface (in a confined aquifer). Read more here about concepts of groundwater.
The Minnesota Geological Survey and the Minnesota Department of Natural Resources have studied, mapped, and photographed the Prairie du Chien and the Jordan aquifers and also the local aquifers in surficial materials. In general, groundwater flows toward the river and stream valleys. The proposed ethanol plant will probably not affect the municipal water supply in Northfield. Read more here about groundwater resources near Northfield.
During low flow conditions, the Cannon River and Rice (Spring Brook) Creek near Northfield are fed by groundwater from the Prairie du Chien aquifer. The Cannon River is also fed by its tributaries, including Wolf Creek and Heath Creek, both of which have large lakes in their watershed areas. If water used in ethanol production is discharged into the surface water system, flows on the Cannon River and its tributaries may change. Read more here about surface water resources near Northfield. [Coming soon]
Technology of ethanol production is changing quickly. Possible ways to mitigate hdyrologic effects include infiltration basins in the local recharge areas of the aquifer, recycling of water in the plant, and conservation measures. Read more here about mitigation proposals. [Coming soon]
We've compiled a list of the resources used to construct this site as well as a bibliography of related material. Read more here about references and resources.
Jack Gibbons, Calvin Lieu, John Nowinski and Mary Savina (students and instructor in Geology 340, Hydrology, winter term 2007, Carleton College) prepared this website for members of the Northfield, Minnesota area community. The site contains a variety of text, map, video and model information about the nature of ground water and surface water sources in the area. We have provided interpretations of some of the data as well as links to the original studies. We hope these resources will be helpful as residents and government agencies make decisions about the plant.
Thanks to:
Hilary Ziols, Cannon River Watershed Partnership
Doug Foxgrover, Information Technology Services, Carleton College
Bob Tipping and Tony Runkel, Minnesota Geological Survey
Doug Lien and Dean Huschle, City of Northfield Water Department
Please direct questions about this site to: Mary Savina (email: msavina - at - carleton.edu)