To address the excess nitrogen, and resulting DO problems, the Connecticut Department of Energy and Environmental Protection (CTDEEP) and New York State Department of Environmental Conservation (NYSDEC) developed A Total Maximum Daily Load Analysis to Achieve Water Quality Standards for Dissolved Oxygen in Long Island Sound (LIS TMDL) that outlines nitrogen reductions necessary to meet water quality standards in the Sound. The U.S. Environmental Protection Agency (EPA) approved the LIS TMDL in 2001.
The Connecticut River Nitrogen Project was a cooperative effort involving staff from NEIWPCC, the states of Connecticut, Massachusetts, New Hampshire, and Vermont, and EPA’s Region 1 and LIS offices. The Connecticut River Workgroup focused its efforts in better understanding nitrogen loading and transport from the Connecticut River watershed to LIS.
In 2010, the Connecticut River Nitrogen Project merged with the LIS TMDL Workgroup. Coordinated by NEIWPCC, the LIS TMDL Workgroup consists of representatives from the Sound’s five watershed states including staff from the CTDEEP, Massachusetts Department of Environmental Protection (MassDEP), New Hampshire Department of Environmental Services (NHDES), NYSDEC, and Vermont Department of Environmental Conservation (VTDEC). The workgroup also includes representatives from EPA’s Region 1, Region 2, and LIS office.
The LIS TMDL Workgroup was established to carry out the LIS TMDL’s phased implementation plan through a five-state watershed process. The plan includes commitments to reevaluate nitrogen reduction targets periodically and revise the LIS TMDL plan accordingly.
The LIS TMDL reevaluation process has been underway since adoption of the original LIS TMDL. The phased implementation plan schedule for the LIS TMDL calls for a reevaluation of the allocations based upon advances in monitoring, modeling, research, implementation, water quality criteria, and other factors. That reevaluation is currently supported by the Long Island Sound Study (LISS), a NEIWPCC program partner.
A future revision of the LIS TMDL may include updated nitrogen allocations for both lower basin sources (CT and NY) and upper basin sources (MA, NH, and VT).
In 2012, the LISS Management Committee and the five watershed states approved a framework for the assessment of the LIS TMDL. This assessment is known as the Enhanced Implementation Plan for the Long Island Sound Total Maximum Daily Load. The plan contains three main elements:
In 2019, NEIWPCC began to support a new work group, the Long Island Sound Study Nitrogen Coordination Work Group. The work group provides the opportunity for coordination between three ongoing Nitrogen reduction efforts:
The Nitrogen Coordination Work Group aims to connect leaders, develop shared goals and a technically sound path forward of the various reduction strategies/programs. NEIWPCC, as a regional interstate agency, is well positioned to support these coordination efforts.
The report completed under part two of the Enhanced Implementation Plan for the Long Island Sound Total Maximum Daily Load is a preliminary and qualitative evaluation of the adequacy of current stormwater and nonpoint source nitrogen control efforts in achieving the LIS TMDL for DO. This qualitative analysis is based on (1) nitrogen loading trends, (2) changes in drivers of nitrogen loading, and (3) the scope and effectiveness of on-the-ground nonpoint source and stormwater nitrogen control efforts.
Each of the five watershed states completed a section of the report. NEIWPCC prepared the watershed synthesis section of the report, which serves as a synthesis and evaluation of TMDL-related implementation efforts at the state and watershed level. Elements of the report are linked below.
This study, completed March 2015 by JJ Environmental, LLC, assessed the feasibility and cost-efficiency of installing low-cost biological nitrogen removal retrofits at select WWTPs in the upper LIS watershed (MA, NH, and VT).
This is a multi-phase effort to develop and implement a feasible tracking system that will allow for quantitative TMDL evaluations of the attainment of stormwater and nonpoint source nitrogen load reductions, as required by the TMDL. The first phase, completed April 2014 by WaterVision, LLC, involved evaluating existing tracking and accounting systems and making recommendations on the general framework for the LIS tracking system.
In 2020, NEIWPCC initiated an exploratory study into the opportunities and obstacles to expand water quality trading to further improve water quality and ecosystem health in the Long Island Sound watershed. Ultimately, the interdisciplinary team found that expanded water quality trading is unlikely to be an effective tool to meet water quality goals under current ecological, economic, and regulatory conditions.