This data set consists of digital water-level-change contours for the High Plains aquifer in the central United States, predevelopment (about 1950) to 2007. The High Plains aquifer extends from south of 32 degrees to almost 44 degrees north latitude and from 96 degrees 30 minutes to 104 degrees west longitude. The aquifer underlies about 174,000 square miles in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This digital data set was created using water-level measurements from 3,643 wells measured in both predevelopment and 2007. The water-level-change contours were initially generated programmatically and then modified manually. The map was reviewed with the relevant data at a scale of 1:1,000,000.