The authors wish to acknowledge the assistance of the U.S. Environmental Protection Agency Region 6 GIS Program and the Source Water Protection Branch, the Oklahoma Department of Commerce, the Oklahoma Conservation Commission, the Oklahoma Tax Commission, the Oklahoma Agricultural Experiment Station at Oklahoma State University, and the University of Oklahoma Geo Information Systems Department for providing many of the data sets included on this disc. The authors also express appreciation to the following individuals for technical reviews, advice, and assistance: Robert Springer, Mark Harrison, James Lowry, Jason Masoner, Scott McKinney, Joe Seig, Mike Sexton, John Sharp, George Nordahl, C.M. Lin, Ian Butler, Marcia Bowerman, Mike Houts, James Winters, Zandra Pendarvis, Ken Brent, David Brown, Scott March, Alexander Weeks, David Parrish, Kelvin Moseman, and John Rader.