Each summer, the bottom waters in the western half of Long Island Sound experience hypoxia, or very low levels of dissolved oxygen. Extensive monitoring and modeling of Long Island Sound have identified the excessive discharge of nitrogen from human activities as the primary pollutant causing hypoxia. Nitrogen fuels the growth of algae in the Sound, which eventually decays, consuming oxygen in the process. There is enough nitrogen added by human activity to cause a hypoxia problem each summer. 

In 2001, Connecticut and New York, in concert with the federal EPA, completed plans for nitrogen control that identifies the maximum amount, or the Total Maximum Daily Load (TMDL), of nitrogen that can be discharged to Long Island Sound without significantly impairing the health of the Sound. One of DEP’s management strategies to reduce nitrogen loading was to develop an innovative nitrogen-trading program among 79 sewage treatment plants located throughout the state. Through the Nitrogen Credit Exchange, established in 2002, Connecticut looks forward to reducing the nitrogen load from that source by nearly 65% by 2014.

General Information

• Long Island Sound Restoration Act - Aid to Distressed Communities Fact Sheet (PDF, 269K)
• Public Act 01-180 - An Act Concerning Nitrogen Reduction in Long Island Sound

For additional general information on the nitrogen control program, please contact Paul Stacey at (860) 424-3704  or Mark Parker at (860) 424-3276.

Baseline Nitrogen Loads, Wasteload Allocation and Permitting

• TMDL Fact Sheet - (PDF, 122K) 
• TMDL Frequently Asked Questions - (PDF, 36K) 
• Text of the Total Maximum Daily Load (TMDL) for Nitrogen- (PDF, 328 K)
  • Public Comment Response- Draft Long Island Sound TMDL- (PDF, 350 K)
  • Public Comment Response- Draft Nitrogen Wasteload Allocation for Point Source Discharge- (PDF, 231 K)
• Nitrogen General Permit - Regulates the discharge of total nitrogen from 79 Publicly Owned Treatment Works (POTW) in Connecticut. 

For further information on baseline nitrogen loads, wasteload allocation and permitting, please contact CT DEP at (860) 424-3704.

Nitrogen Credit Exchange

• Report of the Nitrogen Credit Advisory Board to the Joint Standing Environmental Committee of the General Assembly
  • September 2009 - (PDF)
  • September 2008 - (PDF)
  • December 2007 - (PDF)
  • January 2007 - (PDF)
  • May 2006 - (PDF)
  • December 2004 - (PDF)
  • September 2003 - (PDF)

  For further information on nitrogen credit exchange, please contact Iliana Ayala at (860) 424-3758.

• Betsey Wingfield - (860) 424-3704; Bureau Chief, Bureau of Water Protection and Land Reuse

LIS Water Quality Program & Info