Delineation of contributing areas to selected wells in Ingham County, Michigan

A groundwater-flow model that was constructed in 2009 was updated to reflect recent (2011–12) pumping conditions in the Tri-County region, which consists of Clinton, Eaton, and Ingham Counties, Michigan. As part of local wellhead protection area programs, areas contributing water to local production wells must be periodically updated, because groundwater-flow paths depend in part on the stresses, such as groundwater withdrawals, to the groundwater-flow system. For this current (2013) study, withdrawals from selected city of Lansing production wells were updated, and simulated heads and flows under the new pumping conditions compared favorably to previously measured values. Results of flow simulations indicate that 10-year time-of-travel contributing areas cover approximately 19.4 square miles, and 40-year time-of-travel contributing areas cover approximately 39 square miles.