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Long Island Sound Stream Water Quality and Resources

The USGS conducts studies and monitoring to determine surface-water quality and availability in the Long Island Sound watershed.

Streams and rivers provide critical habitat for freshwater aquatic species and other wildlife. Surface waters are also an important resource for human needs, providing water for municipal, commercial, industrial, and agricultural uses. The ecosystem services provided by stream networks can be impaired by dams, road crossings, reductions in flow due to groundwater and direct surface-water withdrawals, and contamination. In addition to these stressors, surface waters are also vulnerable to potential longer-term perturbations, such as larger flood peaks associated with storm events, from climate change. Streams and rivers are a major source of contaminant loads to Long Island Sound. Nitrogen loading from surface waters has been a major cause of eutrophication and associated hypoxia in Long Island Sound and consequently understanding and quantifying the contribution of streams and rivers is critical for restoring the health of Long Island Sound ecosystems.

USGS operates an extensive surface-water quality monitoring network in Connecticut and Rhode Island, which have dense surface-water drainage networks compared to Long Island. USGS measures flow rates and water quality on all the major tributaries to Long Island Sound and many other locations in the watershed. Many sites have long-term (decadal) records of flow and water quality allowing for assessments of trends in concentrations and loads and changes in response to regulatory and management actions. Data from these networks are used by USGS and other stakeholders to address water-management issues and support other hydrologic studies. USGS also conducts more-focused sampling to support watershed modeling studies in Connecticut and Rhode Island. In addition to data collection, current or recently completed interdisciplinary surface-water studies have been conducted to investigate sediment-bound contaminants, fecal contamination sources, water use, effects of dam removal on river flows, updated low-flow statistics in Connecticut streams, and streamflow estimation at ungaged sites.

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