Regional Groundwater Resources in Western McLean and Eastern Tazewell Counties

In this study, we examined groundwater resources and aquifers in the Mahomet Bedrock Valley, especially the Mahomet Sand and the Sankoty Sand and related aquifers in eastern Tazewell County. The study (1) identified potential aquifers capable of sustaining production of 20 to 50 million gallons of water per day (mgd), (2) estimated the rate and direction of groundwater flow and aquifer recharge potential, and (3) estimated the safe yield of the major aquifers. Our purpose specifically was to compile all geologic and hydrologic information available in the confluence area of the Mahomet and the Mackinaw Bedrock Valleys to determine the areas where highly productive aquifers occur. In addition, areas with the greatest potential for the development of municipal groundwater supplies were identified. We also identified areas where inadequate data exist, but where further exploration may be warranted. Our findings, based on the geologic maps and cross sections prepared during the study and analysis of the hydrologic data compiled, indicate that 70 to 75 million gallons per day of groundwater might be developed from some aquifers within the study area. These quantities of groundwater would most likely be developed from the deep, thick, and extensive sand and gravel aquifers contained within the buried Mahomet Bedrock Valley in southwestern McLean County and related aquifers within the buried Mackinaw Bedrock Valley of eastern Tazewell County. Areas identified as having the greatest potential and overall suitability for municipal well-field development must be verified by test drilling and aquifer tests to ensure anticipated aquifer properties and provide data for proper development and management. More extensive exploration is necessary to locate the best sites for aquifer tests and, ultimately, production wells in areas with good potential. The database, although extensive (mainly drillers' logs of water wells), needs considerable enhancement both in quality and distribution to verify specific geologic and/or hydrologic conditions and conclusions