Photos of the Long Island Sound

Research & Monitoring


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Status and Trends: LISS Environmental Indicators

No Discharge Area



A No Discharge Area (NDA) is an area of a water body or an entire water body into which the discharge of sewage (whether treated or untreated) from all vessels is completely prohibited. (EPA)

Vessel sewage discharge is regulated under Section 312 of the Clean Water Act.  States can have all or portions of their waters designated as a no discharge zone for vessel sewage to protect aquatic habitats or to safeguard human health. (EPA)


This indicator represents progress towards eliminating a major source of pathogens to Long Island Sound.


In 2007, the US EPA approved Connecticut’s designation of all coastal waters of the state as a No Discharge Area for vessels. Connecticut was the third New England state to receive the NDA designation for its coastal waters. In 2011, EPA approved New York’s designation for Long Island Sound waters in New York. A key criteria to the designations were the abilities of the states to provide adequate boat pump-out facilities throughout the coastal region. Since the entire Sound is now a no discharge zone, the indicator is in the presentation as a historical/background indicator. It was a response/performance indicator.

what are historical/legacy indicators?

Some of our indicators are categorized as either historical or legacy indicators. The No Discharge Area indicator is a legacy indicator. A legacy indicator is a type of indicator that is no longer actively tracked by the Long Island Sound Study. This is often due to lack of funding or termination of field sampling programs. A legacy indicator might also be replaced by a more effective indicator or (as in this case) may not need to be updated because the goal has been met. We continue to present these legacy indicators because they can still provide baseline information on conditions in the Sound if the sampling programs resume.

A historical indicator provides perspective on past environmental conditions in Long Island. It is not measured periodically like our other indicators. Many indicators of this type use sediment core samples to measure how conditions in the Sound have changed over hundreds to thousands of years.

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