What is the Nitrogen Reduction Strategy?
EPA is implementing the Nitrogen Reduction Strategy to continue progress in reducing nitrogen (in parallel with continued state implementation of the 2000 Total Maximum Daily Load) as needed to achieve water quality standards throughout Long Island Sound, its embayments, and nearshore coastal waters. The Strategy recognizes that more work must be done to reduce nitrogen levels, further improve dissolved oxygen (DO) conditions and address other nutrient-related impacts on Long Island Sound. EPA’s work to reduce nitrogen complements efforts currently being undertaken through Connecticut’s Second-Generation Nitrogen Strategy, New York’s Long Island Nitrogen Action Plan, the Long Island Sound’s Study’s development of a new regional hydrodynamic and water quality model, Suffolk County’s actions to target priority areas for reduction nitrogen, and other State/Tribal Clean Water Act-related efforts.
Long Island Sound Nitrogen Reduction Dashboard
Click the two-headed arrow at the bottom right corner of the dashboard to open in full wide screen.
The Long Island Sound Nitrogen Reduction Dashboard, produced by EPA, under a contract with Tetra Tech (from 2016-2023), brings together technical studies work conducted by EPA to identify nitrogen target concentrations protective of water quality and designated uses in several of the Sound’s embayments. The interactive tool enables users to view the technical information from the subtask memos (see documents section on this page), and visualize associated data, as well as support management responses. The dashboard was produced using Microsoft Power BI.
Ongoing Technical Coordination and Collaboration
The Dashboard, and related technical studies, were developed under a contract with TetraTech, and with input from state and local partners participating on a technical advisory group.
EPA is working closely to share technical information, data, and approaches with other groups working on developing nitrogen reduction goals and strategies in the Long Island Sound watershed. Some examples include:

During Tetra Tech’s work to support development of the Nitrogen Reduction Strategy, EPA held several public information sessions, including this webinar in November 2018, which highlighted two important deliverables.
Documents
The following documents will help you learn more about the strategy:
EPA Nitrogen Strategy Subtask Memos and Supporting Documents (Updated 12/20/2022):
Project Map: a Study Area map of all watersheds evaluated in this memo.
- Literature Review Memo: Summary of available information concerning potential assessment endpoints and work conducted
- Subtask A: Data summary of individual nitrogen loads for 23 embayments, the Eastern Narrows, the Western Narrows, and Western LIS (Eastern Narrows and Western Narrows combined)
- Subtask B: Data summary of regulated point source discharges to LIS
- Subtask C: Data summary of tributary loadings to LIS, specifically the Connecticut, Housatonic, and Thames rivers
- Subtask D: Summary of existing water quality data collected and analyzed for 23 embayments; the Eastern Narrows; the Western Narrows; the Connecticut, Housatonic, and Thames rivers; and other water quality monitoring stations used for the analysis (includes additional embayments and open water)
- Subtask E: Summary of the hydrodynamic analysis conducted to relate tributary loads to areas of influence and relative contributions to embayments. Also, Response to Independent Technical Review of Subtask E
- Subtasks F/G: Summary of establishing nitrogen endpoints for three Long Island Sound watershed groupings. Also, Response to Independent Technical Review and Public Comments of Subtasks F/G
- Subtask H: Translation of nitrogen target concentrations, as documented in the subtasks F and G memos, into percent reduction target for watershed loads to each embayment waterbody within Long Island Sound
- Public Expert and External Technical Review Summary: Summary report of an independent technical review for Subtask E and Subtasks F/G
- Frequently Asked Questions on Long Island Sound Watershed Permitting (Under Revision)
- Quality Assurance Project Plan for technical approach (methodology),1/11/17
- Performance Work Statement for Phase 1 contract
- Performance Work Statement for Phase 2 contract
Resources
- Slide presentation from 11/29/18 public webinar
- 2017 Connecticut River Data Report
- Response to 11/8/17 public webinar questions
- Slide presentation from 11/8/17 public webinar
- Slide presentation from 12/19/16 public webinar
- Letter to State Commissioners on Proposed EPA Nitrogen Reduction Strategy
- Nitrogen Reduction Strategy
- Slide presentation from Public Meeting on Nitrogen Strategy, 4/15/16