Suffolk County’s Subwatersheds Wastewater Plan (SWP) has evaluated parcel-specific nitrogen loads from wastewater, fertilizer, stormwater, and atmospheric deposition to the groundwater and receiving waters of nearly 200 subwatersheds identified by Suffolk County and stakeholders, including the Wastewater Plan Advisory Committee. The SWP initiative includes the development of first order (initial) nitrogen load reduction goals; establishes ecological sensitivity priority ranks for each of the surface waterbodies, based on nitrogen; and recommendations for implementation of a phased countywide wastewater upgrade program. Work on the SWP began in summer 2016. A draft plan is expected to be released for public comment this summer and the final plan to be released by the end of 2019.
Nassau County Subwatershed Planning is underway. When complete, the plan will help to determine how much nitrogen is entering the groundwater from different sources, e.g. wastewater, fertilizer, stormwater and atmospheric deposition. This effort is being led by Stony Brook University’s School of Marine and Atmospheric Sciences in partnership with the County, the Department of Environmental Conservation and the Long Island Regional Planning Council.
A Nitrogen Load Model, which is central to this work, has been completed and nitrogen loads for each of the county’s 13 subwatersheds have been calculated. The hydrodynamic modeling of the subwatersheds, which is nearing completion, will generate information that will help determine the priority level for the nitrogen present in the subwatersheds and how much nitrogen will need to be removed to achieve water quality goals. The modeling will also inform which nitrogen load reduction strategies to deploy.