Long Island Sound Comprehensive
Conservation and Management Plan

Clean Waters and Healthy Watersheds


Improve water quality by reducing contaminant and nutrient loads from the land and the waters impacting Long Island Sound.

Clean water is the foundation of a healthy Long Island Sound—for human use and recreation, for thriving fisheries, and for productive habitats. The condition of the Sound depends on the quality of the waters draining from the landscapes surrounding it. This connection between the land and water, between healthy, sustainable upland communities and a healthy Long Island Sound is the foundation of the Clean Waters and Healthy Watersheds theme.

While the water quality is improving, Long Island Sound still suffers from hypoxic “dead zones,” beach closures, and other effects of contamination that keeps the Sound from meeting water quality standards. Addressing these issues requires integrated approaches to address polluted stormwater and ground water, contaminants of emerging concern, the resiliency of natural and built infrastructure, and land use planning that protects water resources, includes adaptation to changing climate and extreme weather, and ensures the sustainable use of the Sound’s resources. Additional emphasis is needed on assessing and improving the water and habitat quality of the Sound’s embayments, where much of the public goes for recreation and enjoyment.

Controlling nitrogen pollution remains the top priority. The Total Maximum Daily Load Analysis to Achieve Water Quality Standards for Dissolved Oxygen in Long Island Sound (CTDEP, NYSDEC 2000) set allocations for nitrogen among five watershed states. The plan also identified steps to evaluate additional nitrogen reductions and alternative technologies while continuing monitoring and research programs to assess water quality standards attainment.Through investments to upgrade them, Connecticut and New York are now meeting the nitrogen reduction targets for wastewater treatment facilities, the largest source of nitrogen. Nitrogen reductions from atmospheric deposition and agricultural sources are also meeting TMDL allocations. Nitrogen from on-site wastewater treatment systems, residential turf fertilizer applications and stormwater runoff, however, have remained level or increased. To continue progress in attaining water quality standards it is necessary to manage adaptively, continuing to seek aggressive and practical nitrogen reductions from all sources while evaluating the effectiveness of these reductions. This is all the more important due to the changes in the ecosystem brought about by climate change that may make Long Island Sound more susceptible to hypoxia. With new information on the success of reducing nitrogen and the response of Long Island Sound to these reductions, the TMDL target will need to be assessed and revised as appropriate.

Ecosystem Targets

The following ambitious, but achievable, ecosystem targets have been developed to drive progress toward attaining the Clean Waters and Healthy Watersheds (WW) goal.

Extent of Hypoxia

Measurably reduce the area of hypoxia in Long Island Sound from pre-2000 Dissolved Oxygen TMDL averages to increase attainment of water quality standards for dissolved oxygen by 2035, as measured by the five-year running average size of the zone.

View Extent of Hypoxia Environmental Indicator »

Nitrogen Loading

Attain wastewater treatment facility nitrogen loading at the recommended 2000 Dissolved Oxygen Total Maximum Daily Load allocation level by 2017 and maintain the loading cap. Have all practices and measures installed to attain the allocations for stormwater and nonpoint source inputs from the entire watershed by 2025.

View Nitrogen Loading Environmental Indicator »

Water Clarity

Improve water clarity by 2035 to support healthy eelgrass communities and attainment of the eelgrass extent target.

View Water Clarity Environmental Indicator »

Impervious Cover

Through green infrastructure, low impact development, and stormwater disconnections, decrease by 10 percent the effective area of impervious cover in the Connecticut and New York portions of the watershed by 2035 relative to 2010 baseline.

View Impervious Cover Environmental Indicator »

Riparian Buffer Extent

Increase the percent area of natural vegetation within 300 feet of any stream or lake in the Connecticut and New York portions of the Long Island Sound watershed to 75% (1,030 square miles of natural vegetation) by 2035 from 2010 baseline of 65%.

View Riparian Buffer Extent Environmental Indicator »

Approved Shellfish Areas

Upgrade 5% of the acreage currently restricted or closed for shellfishing by 2035 from a 2014 baseline.

View Approved Shellfish Areas Environmental Indicator »

Sediment Quality Improvement

Reduce the area of impaired sediment in Long Island Sound by 20% by 2035 from 2006 baseline.

View Sediment Quality Improvement Environmental Indicator »


  • Further reducing nitrogen pollution requires addressing sources that are smaller, more diffuse, or more distant from the Sound.
  • Polluted runoff from developed lands contaminates waters with pathogens, which result in closed beaches and restrictions on shellfish harvest areas.
  • Aging infrastructure leaks untreated sewage to coastal waters.
  • Water quality must be improved in bays and harbors to protect and restore submerged aquatic vegetation and benthic community health.


  • Reduce nitrogen from decentralized, on-site wastewater treatment systems and turf fertilizer applications.
  • Work with states and communities in the entire watershed, not just in Connecticut and New York, particularly on low-cost upgrades to centralized wastewater treatment facilities.
  • Document the economic and ecosystem consequences of nitrogen pollution from hypoxia, eelgrass and wetland loss, and increased vulnerability to acidification.
  • Implement smart growth and low impact development policies to minimize the environmental impacts of new development while green infrastructure is increasingly added to areas already developed.
  • Continue capital investments in wastewater treatment infrastructure.
  • Identify and control local pollution sources through community based watershed monitoring (including citizen science) and protection programs.

Learn More

The Management Plan

To fulfill the vision of a restored and protected Long Island Sound the partner agencies of the Long Island Sound Study in 2015 revised its Comprehensive Conservation and Management Plan. Download the 2015 Management Plan.

Public Summary

Pages from CCMP Public Summary Brochure with correct sequence optimized

The public summary provides a concise summary of the Comprehensive Conservation and Management Plan

Year in Review 2016

The spring 2017 issue of Sound Update focuses on Long Island Sound Study’s Year in Review of 2016. Various clean water, habitat restoration, education, and science projects from Connecticut and New York are highlighted. See media center»

EPA Work Plan

The EPA Work Plan report highlights current and planned Management Plan activities. It is available as a PDF Download in the media center.



No Discharge Areas

In 2006, Connecticut took major strides toward banning sewage discharged from boats.
Learn more »

Ribbed Mussels Pilot Study

A pilot study at the location where the Bronx and East rivers meet will study the viability of removing nutrients through the cultivation of ribbed mussels.
Learn more »

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