This data set consists of digital aquifer boundaries for the alluvial and terrace deposits along the Beaver-North Canadian River from the panhandle to Canton Lake in northwestern Oklahoma. Ground water in 830 square miles of the Quaternary-age alluvial and terrace aquifer is an important source of water for irrigation, industrial, municipal, stock, and domestic supplies. The aquifer consists of poorly sorted, fine to coarse, unconsolidated quartz sand with minor amounts of clay, silt, and basal gravel. The hydraulically connected alluvial and terrace deposits unconformably overlie the Tertiary-age Ogallala Formation and Permian-age formations.

The aquifer boundaries established in a ground-water flow model for the aquifer include areas: 1) where the terrace deposits pinch out against relatively impermeable Permian-age formations; 2) where the alluvium has been deposited against relatively impermeable Permian-age formations; 3) where the alluvial and terrace deposits have been eroded and underlying Permian-age formations are exposed at the surface; 4) where the aquifer extends beyond the geographic limit of the study area; and 5) where the aquifer has little or no saturated thickness.

The lines in the data set representing aquifer boundaries along geological contacts were extracted from a published digital surficial geology data set based on a scale of 1:250,000. The geographic limits of the aquifer and areas of little or no saturated thickness were digitized from a folded paper map, at a scale of 1:250,000 from a ground-water modeling report.