This data set consists of digital polygons of a constant recharge value for the alluvial and terrace deposits along the North Canadian River from Canton Lake to Lake Overholser in central Oklahoma. Ground water in approximately 400 square miles of Quaternary-age alluvial and terrace aquifer is an important source of water for irrigation, industrial, municipal, stock, and domestic supplies. The aquifer consists of clay, silt, sand, and gravel. Sand-sized sediments dominate the poorly sorted, fine to coarse, unconsolidated quartz grains in the aquifer. The hydraulically connected alluvial and terrace deposits unconformably overlie Permian-age formations. The aquifer is overlain by a layer of wind-blown sand in parts of the area. A uniform recharge rate of 1 inch per year was used as input to the ground-water flow model for the aquifer and is used in this data set. The features representing boundaries along geological contacts were extracted from published digital surficial geology data sets based on a scale of 1:250,000. The northwest and southeast geographic limits of the aquifer and were digitized from a folded paper map in a ground-water modeling report, at a scale of 1:250,000 Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of recharge used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data.