Connecticut Department of Energy & Environmental Protection

Nitrogen Control Program for Long Island Sound

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

In 2001, the Connecticut Department of Energy and Environmental Protection and New York Department of Environmental Conservation, 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 LIS 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 78 Publicly Owned Treatment Works (POTW). Through the Nitrogen Credit Exchange program established in 2002 and as of 2014, Connecticut had reduced the nitrogen load by nearly 65%. On January 2, 2002, pursuant to Public Act 01-180, the Department issued the General Permit (GP) for Nitrogen Discharges for POWTs (also known as the Nitrogen General Permit) to achieve the Nitrogen removal goals identified in the Nitrogen TMDL.

The GP is reissued every 5 years. Notable changes in the most recent GP include: 1) the requirement to report Nitrate and Nitrite, separately, 2) the transition to an Electronic Nutrient Analysis Report (e-NAR) reporting system, and 3) an updated definition of total nitrogen daily mass loading.

The latest GP continues with the same annual discharge limits listed in the previous GP version and 2014 TMDL allocation. It is important to note that as of 2023, the annual average aggregate equivalent Nitrogen load to LIS has been below this load allocation in 7 of the last 9 years since 2014. Moving forward, the covered POTWs must in aggregate, continue to achieve a reduction in the annual loading of total nitrogen to LIS by approximately 64% from the original baseline TMDL to continue to meet the 2014 load allocation.

General Permit for Nitrogen Discharges
General Information on the Nitrogen Trading Program
Total Maximum Daily Load (TMDL) for Nitrogen

 

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 June 5, 2024