The Hempstead Bay Water Quality Monitoring Program provides a framework for monitoring, analysis, and reporting of water quality within the surface waters of Hempstead Bay (informally known as the Western Bays) and its major tributaries. The program – a collaboration among the Long Island Regional Planning Council (LIRPC), Hofstra University and the Town of Hempstead Department of Conservation and Waterways (ToH C&W) – continues and expands upon the monitoring work that the ToH C&W conducted for nearly five decades in the South Shore of Nassau County. The LIRPC provides high-level program oversight and assistance.
This monitoring program plays an important role in the Long Island Nitrogen Action Plan (LINAP), a multiyear effort funded by New York State and managed by the New York State Department of Environmental Conservation (NYSDEC) and the Long Island Regional Planning Council to: 1) assess the level of nitrogen pollution in Long Island’s surface waters and groundwater, 2) identify the sources of nitrogen pollution, 3) determine nitrogen reduction ecological endpoints, and 4) take action that will reduce nitrogen loads to groundwater and surface waters.
The water quality data derived from samples collected from strategic locations in Hempstead Bay will provide a baseline against which to evaluate changes to nutrient loading that are expected in the next decade as a result of large-scale ecosystem-based and hard-engineered upgrades in the region (e.g. coastal dune restoration, wastewater treatment plant improvements, etc.). This includes sampling around the South Shore Water Reclamation Facility (formerly called the Bay Park Sewage Treatment Plant) before major upgrades are completed.
This program also looks at atmospheric nitrogen deposition which is associated with emissions from fossil fuel-related energy production, fertilizer usage, and transportation emissions. Atmospheric nitrogen deposition is one of the more poorly quantified Nitrogen inputs to the south shore of Long Island. There is a strong need to better quantify this large nitrogen input to Hempstead Bay and the surrounding watershed, in order to reduce uncertainty and better inform nitrogen reduction targets. This information will enhance understanding of what can realistically be accomplished by addressing point sources (such as wastewater treatment plants) alone, considering this large, and likely underestimated non-point source load.
The long-term nature of this monitoring work will advance our understanding of the impacts of severe storms, residential and commercial development, and climate change on our water resources. Overall this water quality monitoring and analysis program will increase our knowledge of nitrogen pollution sources in the region and the associated impacts on environmental quality.
As part of this initiative, Hofstra University and the ToH C&W prepared a historic data analysis of spatial and temporal trends in water quality over time and the potential drivers of these trends.
Map of Water Sampling Stations
Map of Atmospheric Nitrogen Deposition Stations
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- Surface water sampling stations: Forty locations – 30 in the bays and 10 in the tributaries
- Continuous monitoring stations: Three continuous automated monitoring stations (one per bay) with Sea-Bird Scientific WQM instrumentation
- Vertical profile stations: 20 deep water locations within the bays
- Atmospheric deposition-related testing: 12 locations. These locations will factor in the team’s interest in understanding direct-to-bay deposition as well as characterizing the role of major point sources.
Laboratory analysis parameters:
- Water: Chlorophyll a, Total Kjeldhal Nitrogen (TKN), Nitrate, Nitrite, Ammonium, Orthophosphate, Total Coliform, Silica. (TKN analysis provides the opportunity to quantify the amount of nitrogen contained in organic form.]
- Nitrogen Deposition: Nitrate, Ammonium
Field measurement parameters:
- Water characteristics: The following parameters will be recorded using Sea Bird Scientific WQM instruments and, monthly, using YSI Sondes: dissolved oxygen, fluorometric Chlorophyll, salinity/conductivity, temperature, sampling depth, turbidity, and pH (YSI only).
- Surface waters: Readings will be taken at one-meter depth using YSI Sondes at the same locations and time as sample collections for laboratory analysis.
- Vertical profiles: YSI Sondes will be used to measure the aforementioned parameters at an additional 20 deep water locations on a monthly basis. At these locations, measurements will be taken across the entire water column, from the surface to maximum depth.
- Continuous monitoring: TOH C&W will reinstate and expand the continuous monitoring (15-minute interval) data collection program on using the long deployment Sea-Bird Scientific WQM units at three locations within the study area.
Historic Data Analysis:
The Hofstra-TOH C&W project team analyzed the historic water quality records for trends and gaps incorporating an application of advanced geostatistical time series analysis. The team conducted an extensive analysis using all readily available historical water quality data in the region, which culminated into a report entitled Water Quality Trends in Hempstead Bay, NY from 1968-2017: A Historical Data Analysis and Report for Long Island’s South Shore Estuary Reserve Western Bays.
This analysis enables a better understanding of spatial and temporal trends in water quality over time and their potential drivers. This work informs the distribution of long-term water quality stations that will be deployed in the region.
Quality Assurance Project Plan:
A Quality Assurance Project Plan (QAPP) for this monitoring program was approved by the NYS Department of Environmental Conservation in December 2019.
A QAPP is a document that outlines the quality assurance and quality control procedures used to ensure that a monitoring program collects high quality data. It is an important planning and operating tool that outlines the project’s methods of data collection, storage and analysis. The QAPP helps to ensure that the data collected can be used for its intended purpose. Importantly, the individuals interested in the monitoring project, or the agencies that make decisions based on the data and information from the project, will have a better understanding of the quality of the underlying data.