Long Island Sound Groundwater Quality and Resources

Groundwater is a critical resource for human needs and an important contributor to the health of freshwater and coastal marine aquatic ecosystems. As a resource for human needs, groundwater is a major source of water for residential, commercial, industrial, and agricultural uses. Groundwater is vulnerable to depletions from excessive withdrawals, contamination, and potential longer-term perturbations from climate change. Nitrogen from wastewater disposal and fertilizer application is a major source of groundwater contamination in the Long Island Sound watershed and the discharge of groundwater and associated loading of nitrogen to streams and coastal embayments is a critical factor in the health of these ecosystems. Because groundwater residence times range from years to many decades there are substantial lags between management actions to reduce nitrogen inputs and changes in nitrogen loading to freshwater and marine systems in Long Island Sound.  

USGS is conducting several regional groundwater modeling studies on Long Island and along the Connecticut coast of Long Island Sound.  Models are used to evaluate groundwater sustainability and provide quantitative estimates of groundwater discharge and contaminant loading to streams and coastal waters in the Long Island Sound watershed. Other groundwater studies focused on water use, contaminant transport, and coastal flooding are also underway or recently completed. In addition to investigations, USGS has been measuring groundwater levels from extensive observation well networks on both the north and south sides of Long Island Sound for over 50 years in many locations. Data from these networks are used by USGS and other stakeholders to address water-management issues, such as drought monitoring and assessment of long-term groundwater-level trends, and to support other hydrologic studies.

Explore the Groundwater Quality and Resources page for more information on current and recently completed USGS studies, monitoring programs, and publications.