«'«W"W«WRK*(!**i-.,. GROUND-WATER FOR THE FUTURE Atlantic

Ground water is among the Nation's most important natural resources. It provides drinking water to urban and rural communities, supports irrigation and industry, sustains the flow of streams and rivers, and maintains riparian and wetland ecosystems. In many areas of the Nation, the future sustainabil-ity of ground-water resources is at risk from overuse and contamination. Because ground-water systems typically respond slowly to human actions, a long-term perspective is needed to manage this valuable resource. This publication is one in a series of fact sheets that describe ground-water-resource issues across the United States, as well as some of the activities of the U.S. Geological Survey that provide information to help others develop, manage, and protect ground-water resources in a sustainable manner. G round-water resources along the Atlantic coastal zone of the United States are vulnerable to saltwater intrusion and to contamina-tion by nutrients. Saltwater intrusion, the movement of saline water into fresh-water aquifers (fig. 1), is most com-monly caused by ground-water pumping near the coast. Nutrient contamination results from many human activities and has caused widespread increases of nitrate in shallow ground water nation-wide (U.S. Geological Survey, 1999). High salinity or nutrient concentrations can make ground water unfit for public consumption. Moreover, discharge of nutrient-contaminated ground water to coastal waters can trigger dense algal blooms that result in habitat changes and oxygen depletion, ultimately affect-ing the structure and function of coastal ecosystems. This fact sheet reviews some of the issues associated with saltwater intrusion and discharge of nutrient-contaminated ground water along the Atlantic coastal zone. Also described are some of the activitie