The Washita River alluvial deposits between Clinton and Anadarko primarily are fine-grained sand and clay, and lesser amounts of coarser-grained material. These deposits range in thickness from 0 to 120 feet and average about 64 feet. Well yields range from only a few gallons per minute in some of the sandy clay beds to more than 240 gallons per minute (gpm) in sections where a higher percentage of coarse material has been deposited. Test pumping indicates that wells yielding 60 to 150 gpm could be developed in about 50 percent of the valley and wells yielding more than 150 gpm in about 10 percent. The higher yields generally occur along a relatively narrow buried channel where the alluvial deposits are thicker and coarser than the surrounding alluvium. This area is not discernible at the surface and must be located by test drilling.