Water quality in the Hudson River estuary has improved remarkably over the last 50 years, benefiting drinking water supplies, recreation, and habitat. However, the legacy of past land uses, industries, and development supporting millions of residents in the watershed presents ongoing challenges to clean water. Collaborations among concerned residents, interested businesses, dedicated nonprofit organizations, watershed community groups, and government agencies at all levels are needed to continue progress toward our Hudson River Estuary Action Agenda goal of ensuring that Hudson River water quality supports drinking water, swimming, fishing, navigation, and ecosystem needs.
The Hudson River National Estuarine Research Reserve (HRNERR) and Hudson River Estuary Program collaborate with partners to conduct continuous real-time water quality monitoring at stations along the estuary to understand current water quality conditions and trends. We also work with local and regional partners to plan and implement water quality improvement projects.
Hudson River Environmental Conditions Observing System (HRECOS)
The Hudson River Environmental Conditions Observing System (HRECOS) network includes monitoring stations along the Hudson and Mohawk Rivers and New York City Harbor that collect high-frequency water quality data to support science, education, recreation, and management. Stations record conditions every 15 minutes and transmit data in real-time to the HRECOS website. Monitoring parameters include water temperature, dissolved oxygen, turbidity, acidity, and specific conductance. You can use the Live Data dashboard to explore current conditions, or request data on our portal.
HRECOS is currently managed by HRNERR and operated through a collaboration of governmental, academic, and private institutions with a shared interest in the health of the Hudson River Watershed. HRECOS was developed as an expansion of the HRNERR System-Wide Monitoring Program and integrates HRNERR site data along with data collected by a network of partners.
For more information about water quality trends documented through HRECOS, visit the State of the Estuary 2025.
Hudson River National Estuarine Research Reserve (HRNERR) System-Wide Monitoring Program (SWMP)
Since 1991, the Hudson River National Estuarine Research Reserve (HRNERR) has monitored water quality, weather, and nutrients within the Hudson River Estuary as part of the national System-Wide Monitoring Program (SWMP). All stations collect data in 15-minute intervals and transmit data in real-time to the Centralized Data Management Office, where anyone can download, graph, or view conditions at the research reserve sites. Monthly water samples from the sites are also analyzed for nutrients including ammonium, nitrate, phosphate, sulfate, chloride, suspended sediment, and chlorophyll. The data has directed vital research and guided the management of the Estuary.
You can learn more about water quality, nutrient, and weather trends in HRNERR’s annual SWMP Status Reports, as well as other information about the Reserve’s monitoring data, at the HRNERR website.
Hudson River Water Quality Assessment (Troy – Yonkers)
In 2023–2024, DEC partnered with the United States Geological Survey (USGS) to perform water quality monitoring in the Lower Hudson River estuary from Troy to Yonkers to determine if the river is meeting applicable NYS water quality standards. Water quality data are available at the following locations:
- Division of Water Monitoring Data Portal: As data becomes available and passes quality control standards they will be added to the data portal.
- Vertical Profile Data: A CSV of vertical water-quality profiles of the Hudson River collected over two field seasons from May through October 2023 and May through September 2024.
Current waterbody classifications and NYS Waterbody Inventory/Priority Waterbody List status are available to view under the Stream and Watershed Layers on the Hudson Valley Natural Resource Mapper and in the DECinfo Locator. For more information on assessment and listing visit DEC's Water Quality Assessment webpage. For questions regarding the 2023-24 Hudson River water quality data, contact: [email protected].
