The collection of hydrologic data and the investigation and assessment of the quantity, quality, and use of surface-and groundwater resources are major components of the mission of the Water Resources Division, U.S. Geological Survey. To accomplish this mission the Arizona District is organized into a district office in Tucson and field offices in Tempe, Flagstaff, and Yuma, Arizona. These offices are geographically located in the State to provide access and response to hydrologic events and to maintain liaison with cooperating State and Federal agencies. The Arizona District technical staff is organized into two major sections: (1) the Hydrologic Data Section, which maintains the systematic hydrologic-data programs for the State, and (2) the Hydrologic Investigations and Research Section, which investigates and assesses the quantity, quality, and use of the State's water resources. The Hydrologic Data Section maintains a network of hydrologic data-collection sites and compiles hydrologic data collected from these sites for public distribution. These hydrologic data include records of (1) stage and discharge of principal river and tributaries; (2) chemistry and suspended-sediment concentration of selected rivers; (3) levels and quality of principal aquifers; and (4) surface-and groundwater use. Data from this network are compiled and entered in the Survey's National Water Information System data base, located in Reston, Virginia, and are published annually in the report series "Water Resources Data Arizona." The Hydrologic Data Section has made substantial progress in developing a real-time hydrologic data base. Surfaceand groundwater data at selected sites are transmitted to the Arizona District's central hydrologic data base at regular intervals using satellite telemetry. This information is accessible to scientists or water managers to assess current hydrologic conditions. The Water Resources Division (WRD) will implement the National Water Information System-II (NWIS-II) during 1995. This database system will replace the database systems currently in use. NWIS-II will provide data-handling and data-storage procedures that are uniform across all disciplines of WRD, will serve as an archive for all data used in published products, will provide a national water data base and index, and will comply with industry software and data standards. The investigation and assessment of the surface-and groundwater resources of Arizona is accomplished through a series of projects conducted by the Hydrologic Investigations and Research Section. Each project is managed by a designated project chief who is responsible for managing the investigative aspects of the project, maintaining a project budget, and providing public access to the findings of the project. Program emphasis for the Arizona District in 1995 96 is to provide timely, objective hydrologic information to Federal, Tribal, State, and local agencies regarding water-supply availability, water-source identification, and water-resource management. Programs are expected...