Comparing water quality data with standards, criteria, or management guidelines can be a major part of any water quality assessment. The effort required for manual comparisons of data for a large reservoir or watershed project can become a formidable task. One solution to the problem is to utilize a digital computer in conjunction with appropriate software designed to compare numerical water quality data with Federal and State criteria or standards as well as user-specified management guidelines. Aside from reducing the labor cost of data analysis, more accurate, rapid, and flexible analyses of water quality data can be readily performed. Utilization of such software can also allow a more extensive comparison of water quality data and criteria than would otherwise be possible. A software package of this type has been developed for the U.S. Army Corps of Engineers, Vicksburg District. The program, WATERCHECK, is used primarily in comparing project water quality data with Federal and State standards; a comparison which was not always feasible without the program. The processing of a data set which previously required 2–4 man-days now can normally be accomplished in 1 man-day. WATERCHECK is especially useful for State and regional water quality management organizations responsible for assessment of large amounts of data. User-specified options which allow the data to be compared against criteria or standards for different water use classifications are useful for water resource planning purposes as well as water quality management.