Surveillance activities of the U.S. Geological Survey Louisiana District include long-term, hydrologic-data-collection sites that serve a current-purpose, management function and (or) that furnish a data base for interpretative studies. The proposed program for 1982 includes a network of 69 surface-water data sites (continuous gaging stations), 250 flood-data sites (crest-stage stations), 679 ground-water wells (water-level observation and water-quality monitor wells), and 138 water-quality sites. The geographic distribution of the data sites is shown in the report. Interpretive studies have objectives that are oriented toward a particular geographic area , to a particular set of hydrologic phenomena, or to obtain information for use in solving specific problems. Current studies of interest to agriculture include the following: (1) Flood hydraulics and hydrology, (2) Low-flow or base-flow of streams in Louisiana, (3) Hydrologic studies in southwestern Louisiana, (4) Hydrologic impacts of surface mining in northern Louisiana, (5) Sparta aquifer study, and (6) Limnology of freshwater lakes. A network of partial record sites is also maintained to monitor specific flows. Peak stages (crest stage) are only recorded at sites where flood information is of interest. At other sites, only the low-flow or base-flow recession is obtained for use in determining relations between ground water and surface water, to assess water supply, and for effluent studies. (USGS)