A regional groundwater flow model (https://pubs.usgs.gov/sir/2009/5244/) was updated to reflect 2017 pumping conditions in the Tri-County Region covering most of Clinton, Eaton, and Ingham Counties, Michigan. This model was developed to simulate the regional hydrologic system in Tri-County area and continues to be used for planning and protection of area water supplies. Revised contributing area delineations in response to recent pumping conditions were needed for local wellhead protection area programs. The model was calibrated to water level observations for 2017 from well driller logs, average water levels for 2012-17 from active USGS observation wells, and estimated baseflow for 2012-16 from USGS streamgaging station measurements. The model was used to delineate 10- and 40-year contributing areas to selected wells in Lansing and East Lansing, Michigan. This USGS data release contains all of the input and output files for the MODFLOW and MODPATH simulations described in the associated model documentation report (https://doi.org/10.3133/ofr20181133).