Different definitions and categories of use are used by different agencies. The different definitions and approach to data compilation require the USGS to recompile the Oklahoma Water Resources Board data and add data from other sources to obtain the information needed for the national program. For example, the USGS and the Oklahoma Water Resources Board primarily compile data by site of withdrawal, but some agencies compile data by site where used or final user. When large quantities of water are transferred between other counties or river basins, these differences in accounting procedures can create differences in reported use. Also, the definitions of the various categories vary between agencies. For example, the Oklahoma Water Resources Board has a public water-supply category that includes deliveries to residential, commercial, and industrial users, plus sales to other municipalities. Their industrial and commercial categories are for self-supplied users only. Therefore, the components with public water supply must be extracted and compiled under several other use categories. A USGS animal specialty category such as fish farming had to be extracted from commercial and agricultural (nonirrigation). Thus, all information contained in this web page is compiled from several sources and cannot be compared directly to the Oklahoma Water Resources Board water-use totals.
Total withdrawals by water source were obtained by the Oklahoma Water Resources Board from mail-out surveys. The Oklahoma Water Resources Board developed special data-retrieval procedures for the USGS water-use program. The data were provided to the USGS as withdrawal-site totals by use category by county, and were further sorted by river basin and aquifer within the county. Irrigation withdrawals also were collated by crop so the consumptive use could be estimated. These data were compared with 2000 Oklahoma agricultural statistics (Oklahoma Agricultural Statistics Service, 2001). Water-supply water-use data were supplemented by unpublished data supplied in written communications by the Cities of Oklahoma City and Tulsa and by the Grand River Dam Authority. Livestock water use was estimated from animal population figures supplied by the Oklahoma Agricultural Statistics Service (2001) and cross-referenced with the Oklahoma State University Agricultural Extension poultry report by Britton and Berry (2001) and the Oklahoma State University Economics Department and Oklahoma Pork Council swine report by Williams and Luce (2002); and consumption coefficients were supplied by Oklahoma State University Agricultural Engineering Department (R.L. Huhnke, written commun., 1991). The average annual precipitation may be helpful in interpreting the estimated withdrawal data for 2000; the 2000 statewide average precipitation was 36.13 in.
Water-use data used to derive the estimates contained in this web page were made available to the USGS by the Oklahoma Water Resources Board. Specific details about withdrawals, sources, transfers, and retrievals were provided by T. Andy Scurlock and Jann P. Hook. Individual water users supplied original withdrawal information to the Oklahoma Water Resources Board.