Water-resources activities of the U.S. Geological Survey in Arizona consist of collecting water- resources data and conducting interpretive hydrologic investigations and research. The water- resources data and the results of the interpretive investigations and research are published or released by the U.S. Geological Survey or by cooperating agencies. The report describes the data-collection activities and water-resources investigations in Arizona for fiscal years 1986-91 (October 1, 1985, to September 30, 1991). The report includes a brief description of the origin of the U.S. Geological Survey, the basic mission of the Water Resources Division, organization of the Arizona District, sources of funding, and a summary of water conditions in Arizona. Information is given for each project and includes the objective, approach, progress and results, and plans for the following year. The report also includes a list of publications prepared by the Arizona District, Water Resources Division, U.S. Geological Survey, that were published from 1984 to 1991.