Conceptual design of the surface water component of the national water quality assessment (NAWQA) program

The U.S. Geological Survey started, in a pilot phase, a program to provide nationally consistant information on the status and trends in the quality of the Nation´s fresh water and to identify and describe the relationships between both the status and trends in water quality as they relate to natural factors and the history of land-use and land- and waste-management practices. The program is organized into hydrologically based study units and, for the study of surface water, involves a combination of fixed-station, synoptic and intensive study approaches.