DEEP: Nitrogen Control Program for Long Island Sound

Nitrogen Control Program for Long Island Sound

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 DEEP and New York DEC, in concert with US 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 DEEP’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 has reduced the nitrogen load from that source by nearly 65% by 2014.

On January 2, 2002, pursuant to Public Act 01-180, the Department issued the General Permit for Nitrogen Discharges (also known as the Nitrogen General Permit). The Nitrogen General Permit was reissued with revised discharge limits consistent with the Long Island Sound TMDL on December 21, 2005; again in 2010; and recently renewed effective January 1, 2016. The Nitrogen General Permit will expire on December 31, 2018.

The current General Permit for Nitrogen Discharges for Publically Owned Treatment Works (POTW's) continues with the same permit limits as listed in the General Permit for the year 2014. These facilities, in aggregate, must continue to achieve a reduction in the annual loading of total nitrogen to Long Island Sound by approximately 64% from the original baseline TMDL in order to continue to meet the target 2014 waste load allocation.

On June 5, 2015, Public Act 15-38, an act concerning the sustainability of the Nitrogen Credit Exchange Program was signed by the Governor.   DEEP and the Nitrogen Credit Advisory Board (NCAB) proposed the legislation to move the nitrogen trading program to self-sufficiency ("state subsidy neutral") for the 2015 trading year credit exchange transactions to be completed by August 2016. The Nitrogen Trading Program has been a successful approach for cost-effectively meeting the 2014 Total Maximum Daily Load for reducing nitrogen in Long Island Sound. Over $450 million in grants and loans from the Clean Water Fund for municipal sewage treatment plant nitrogen removal upgrade projects is expected through 2018. It is estimated that $300 - 400 million have been saved by not forcing municipalities to upgrade all at once.

The Nitrogen Trading Program’s success has produced a situation where significantly more credits are produced than are needed. Projections showed the State subsidization of the program growing to over $5 million by 2018. This level of continued subsidization could not be sustained. To address this, DEEP and NCAB proposed continuing the trading program while moving it to a self-sufficiency model where the buyer’s payments are shared proportionally by the sellers. Public Act 15-38 enacts this proposal. 

General Permit for Nitrogen Discharges

    General Information on the Nitrogen Trading Program

    Total Maximum Daily Load (TMDL) for Nitrogen

    Reports of the Nitrogen Credit Advisory Board to the Joint Standing Environment Committee of the General Assembly by Calendar Year 
    For more information on:
    Nitrogen Credit Exchange Program, please contact Iliana Raffa at (860) 424-3758.
    Baseline nitrogen loads, waste load allocation and permitting, please contact CT DEEP at (860) 424-3704.


    Content last updated: November 16, 2017