Advances in the treatment of municipal and industrial waste and changes in manufacturing and processing techniques over the past 25 years have led to improved water quality in many parts of the Delaware River Basin. One indication of this improvement is the return of shad runs to the Delaware River. The presence of toxic compounds, however, still leads to consumption advisories for many fish species, and nutrient loadings adversely affect water quality and the health of ecological communities. Many of the water-quality issues in the Delaware River Basin can be related to the high human population density in the area and related activities associated with urban, industrial, and agricultural land use. Most concerns are related to human health (the quality of domestic water supply, the safety of water contact recreation, and the safety of eating game fish) and the health of ecological communities.
Some of the major water-quality issues that are currently being addressed by water-resource managers in the Delaware River Basin include--
- Relation of land use to nonpoint sources of contaminants.
- Effects of natural settings on the distribution, fate, and effects of contaminants in water, sediment, and biota.
- Relations between streamflow and loadings of nutrients, contaminants, and pathogens.
- Effects of nutrients and habitat on algae and macrophytes in streams, lakes, and estuaries.
- Distribution of toxic substances, particularly polychlorinated biphenyls (PCBs), and trace elements in surface water, ground water, and biota.
- Presence of human pathogens and pesticides in drinking-water supplies and recreational waters.
- Effect of dams, impoundments, and diversions on water quality, and on the health of fish and benthic invertebrate communities.
- Development of management strategies for protecting areas of existing high water quality.
- Effects of on-lot septic systems and reduced streamflow caused by ground-water withdrawals on water quality and ecological communities.
- Distribution of natural radioactivity in domestic ground-water supplies.
- Effects of ground-water/surface-water interactions on water quality.
- Effects of coal-mine discharges on water quality and ecological communities.
The Delaware River Basin NAWQA study will characterize spatial and temporal variations in water quality and relate those changes to natural processes and human factors. This scientific characterization can be used by water-resource managers, State and local governments, citizens' groups, and planners as a basis for implementing water-quality management actions and evaluating long-term changes in water quality.
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