U.S. Geological Survey
U.S. Geological Survey
The USGS provides maps, reports, and information to help others meet their needs to manage, develop, and protect America's water, energy, mineral, and land resources. We help find natural resources needed to build tomorrow, and supply scientific understanding needed to help minimize or mitigate the effects of natural hazards and environmental damage caused by human activities. The results of our efforts touch the daily lives of almost every American.
The Delmarva study has provided pol-icymakers and resource managers with important information on the extent of water-quality contamination caused by agricultural and residential land use. The study has shown that high concentrations of nitrate (greater than 10 milligrams per liter), a known hazard to human health, are found in most of the surficial aquifer, including deep parts of the aquifer used for water supply (fig. 1). Pesticides generally are not found in deep parts of the surficial aquifer, but they could migrate to these zones during the next few decades. The Delmarva study also showed that ground water containing high concentrations of nitrate will continue to discharge to streams draining into Chesapeake Bay for at least the next few decades. Accordingly, ground-water quality, as well as surface-water quality, is an important consideration in land-use practices designed to improve water quality in the Chesapeake Bay watershed. The issue is of vital importance to local resource managers and concerned citizens because the States in the Chesapeake Bay watershed have made a commitment to reduce contamination of the Bay significantly by 2000.
Figure 1. Areas of high concentrations of nitrate in the Delmarva Peninsula.
The USGS provides technical assistance to the U.S. Environmental Protection Agency (EPA), Region III, Resource Conservation and Recovery Act Division. This assistance can take the form of computerized simulations of ground-water flow in the Delaware City area (fig. 1). Specific activities include data collection, developing models of ground-water flow by means of a geographic information system, and modeling possible ways to reduce ground-water contamination caused by leaks from hazardous-waste sites in the Delaware City area. These efforts will help managers at the EPA to develop effective and economical plans for reducing contamination in this area and to address the concerns of local citizens.
The Delaware Department of Transportation (DelDOT), which provided cooperative funds for studies of stream-bed scour at highway bridges and of flood magnitude and frequency, and the Delaware Department of Natural Resources and Environmental Control (DNREC), which cooperated with the USGS in a study of drought frequency, are two of the agencies that rely on the results of USGS studies. Results of these studies are used by the DelDOT to reduce maintenance, repair, and replacement costs for highway bridges and to improve the safety of travelers during floods. The DNREC can use the results of the drought study to improve analyses of water appropriation and use during droughts, thereby allowing appropriate water-supply decisions to be made to ensure that the water needs of the greatest number of people are met to the greatest possible extent. Such contributions to public safety and well-being make USGS reports valuable to the citizens of Delaware.
Figure 2. Water-quality data-collection sites in Delaware.
The detection of contamination and the prediction of contaminant movement in ground water are of critical importance in the part of Delaware south of the C & D Canal, where ground water supplies most freshwater needs. Similarly, maintaining adequate supplies of surface water for fisheries and other industries, the support of wildlife, and recreation are important issues. The role of the USGS in collecting these data to address these issues is essential. The USGS systematic data-collection program in Delaware receives cooperative support from the Delaware Geological Survey, the Delaware Department of Natural Resources and Environmental Control, the Delaware Department of Transportation, the U.S. Environmental Protection Agency, the U.S. Army Corps of Engineers, and other organizations. The availability of up-to-date data on water levels and water quality, as well as its use by water-resource managers, to help maintain the quantity and quality of water needed for future use, make the USGS systematic data-collection program an integral part of water-resources management in Delaware.
The USGS and the State of Delaware have maintained a strong cooperative relation over the past few years. The Delaware Geological Survey, in conjunction with the USGS, funded a 4-year statewide revision of the 1:24,000-scale maps covering Delaware. With that task finished, the USGS will soon complete production of the last of four categories of digital line graph data for the entire State; these maps will be available for use by anyone who has needs for digital spatial data of Delaware.
The USGS has entered into a partnership with the Delaware Department of Transportation to produce color infrared digital aerial photographs that offer an excellent backdrop when used with other computerized data layers to visualize large geographic areas. This will assist transportation planners to predict possible affects of new traffic patterns as a result of road realignment, for example, and to estimate construction costs.
from U.S. Department of the Interior, U.S. Geological Survey, Fact Sheet FS-008-95