About the Study

Working together to protect and improve the health of Long Island Sound

What is Being Done to Restore and Protect the Long Island Sound?

Since the federal Clean Water Act became law in 1972, investments in water pollution control programs have led to measurable improvements in the water quality of Long Island Sound. Obvious sources of pollution were controlled through permit programs. Tidal wetlands were protected, wastewater treatment plants improved, and industrial discharges controlled.

However, to fully restore the health of the Sound, a cooperative effort focusing on the overall ecosystem was needed. As a result, EPA, New York, and Connecticut formed the Long Island Sound Study (LISS) in 1985, a bi-state partnership consisting of federal and state agencies, user groups, concerned organizations, and individuals dedicated to restoring and protecting the Sound. In 1994, the LISS developed a Comprehensive Conservation and Management Plan to protect and restore Long Island Sound. This plan was updated in 2015 with ambitious targets to drive further progress through 2035.

LISS’s partners have made significant strides in implementing the plan, giving priority to reducing nutrient (nitrogen) loads, habitat restoration, public involvement and education, and water quality monitoring.

Nitrogen (Hypoxia) Management

  • In 2001, the EPA approved Connecticut’s and New York’s plan, called a Total Maximum Daily Load (TMDL), for achieving the 58.5 percent nitrogen reduction to reduce nitrogen loads from human sources. By 2016, the states attained the goal. By 2018, upgrades to wastewater treatment plants have resulted in an annual reduction of more than 50 million pounds of nitrogen to the Sound from peak years in the early 1990s.
  • In 2015, EPA embarked on a new Long Island Sound Nitrogen Reduction Strategy with a primary focus on achieving clean water in harbors, bays, coves, and other embayments to the Sound through efforts to remove nutrient pollution from urban stormwater and turf fertilizer, and from coastal on-site wastewater treatment systems such as septic tanks.  

Habitat Restoration

  • From 1998 to 2022, nearly 3,000 acres of habitat, including tidal wetlands and forest, have been restored in Connecticut and New York in the Long Island Sound watershed.
  • From 1998 to 2022, 433 miles of river migratory corridors have been restored for anadromous fish passage by installing fishways and removing dams.

Public Involvement and Education

  • The Long Island Sound Study initiated the Long Island Sound Futures Fund in 2005 through the EPA’s Long Island Sound Office and the National Fish and Wildlife Foundation. Through 2023, the Futures Fund has invested $56 million in 640 community-based projects. The program has generated an additional $65 million in grantee matching funds towards these projects for a total conservation impact of $121 million. The projects have opened 121 river miles for fish passage, restored 842 acres of fish and wildlife habitat, treated 208 million gallons of stormwater pollution, and engaged 5 million people in protection and restoration of the Sound.
  • LISS partners hold conferences, summits, and workshops where municipal leaders, research scientists, and educators can share their experiences and highlight their success stories regarding issues such as nitrogen reduction, habitat restoration, research on living marine resources, land use, open space, and smart growth.
  • The International Coastal Cleanup takes place annually on the third Saturday of September. Thousands of volunteers from Connecticut and New York remove and document the trash that they collect along the shoreline and underwater on that weekend and on other dates in September and October. Visit the Ocean Conservancy for more information.

Water Quality Monitoring

  • The Connecticut Department of Energy and Environmental Protection and the Interstate Environmental Commission, on behalf of the Long Island Sound Study, conduct a Long Island Sound Water Quality Monitoring Program. Surface and bottom waters are monitored from staff on board research vessels. Testing parameters include water temperature, salinity, dissolved nitrogen, particulate nitrogen, and dissolved oxygen. LISS also provides support to LISICOS, a real-time monitoring program using equipment on buoys at stations throughout the Sound.
  •  LISS has helped provide financial and technical support to Save the Sound in establishing the Unified Water Study, a new water quality monitoring protocol developed so groups around Long Island Sound can collect comparable data on the environmental health of the Sound’s bays, harbors, covers, and other coastal waters. This groundbreaking water testing program is dramatically increasing available data on the health of Long Island Sound.

To continue progress, LISS’s partners in 2015 totally revised the Comprehensive Conservation and Management Plan to address ongoing and new challenges. The 2015 plan is organized around four themes, each with an overall goal:  

  1. Clean Waters and Healthy Watersheds – Improve water quality by reducing contaminant and nutrient loads from the land and the waters impacting Long Island Sound.
  2. Thriving Habitats and Abundant Wildlife – Restore and protect the Sound’s ecological balance in a healthy, productive, and resilient state for the benefit of both people and the natural environment.
  3. Sustainable and Resilient Communities – Support vibrant, informed, and engaged communities that use, appreciate, and help protect Long Island Sound; and.
  4. Sound Science and Inclusive Management – Manage Long Island Sound using sound science and cross-jurisdictional governance that is inclusive, adaptive, innovative, and accountable.

The plan sets 20 ambitious, but achievable ecosystem targets for these goals and identifies detailed strategies and actions to drive progress to attain them. 

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