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Nassau County Subwatershed Planning

Nassau County is working with Stony Brook University's School of Marine and Atmospheric Sciences (SoMAS) to develop its subwatershed plan. The plan is in the process of being developed and will be similar to the Suffolk County plan in many aspects. There is a Nassau County Subwatershed Advisory Workgroup that provides input on the development of the plan and helps Nassau County advance load reduction strategies.

This effort is in two phases, which are described below.

Phase I

During Phase I, a workgroup was assembled and met to determine the pathway for creating an appropriate subwatershed plan for the County. The first meeting of the Nassau County Subwatershed Advisory Workgroup was held in 2017. During that meeting, members were introduced to the nitrogen load model (NLM) and hydrodynamic modeling currently underway. These models are the basis for determining the priority subwatersheds in the County and inform nitrogen load reduction strategies.

Following the initial Advisory Workgroup meeting, multiple conversations were held between Nassau County, DEC, and SoMAS to develop the first iteration of the subwateshed plan, which is the Nitrogen Loading Modeling for Nassau County Subwatersheds Report (PDF). This report outlines the data sources, modeling efforts, and results of the analysis for the 11 of the subwatersheds in the county.

Phase II

Nassau County is in the beginning stages and is planning a series of stakeholder meetings with the Nassau County Subwatershed Advisory Workgroup to update the report into a comprehensive Nine Element Subwatershed Plan for reducing nitrogen loading. These meetings will be held in conjunction with SoMAS to provide the most up-to-date model results and implementation scenarios to the workgroup, in order to make decisions regarding best next steps. Meeting announcements and summaries will be available as the meetings get underway.

A kick-off meeting for the Nine Element Plan was held on July 10, 2020 to start the processes of gathering input from stakeholders for development of the plan. The stakeholders heard from Nassau County officials, DEC staff, and Dr. Gobler from SUNY Stony Brook's School of Marine and Atmospheric Science.

A stakeholder meeting was held on August 9, 2021 to present the findings from the modeling efforts. Dr. Gobler presented the results of the modeled nitrogen load currently entering the Nassau County subwatersheds, and also presented potential implementation activities aimed at reducing nitrogen and how the projects could impact the loading. The next steps are for the Nine Element Plan to be drafted.

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