One season, more than 15,000 water quality measurements
How Riverkeeper monitored New York’s waterways in 2026
November 4, 2026
Riverkeeper Team
This year, Riverkeeper continued to expand our signature water quality monitoring program. In the Hudson River watershed, Riverkeeper and our partners took more than 15,000 measurements at more than 250 sites, including nutrient (nitrate, nitrite, ammonia, urea, and phosphorus) monitoring at 90 locations. These data will enable us to better understand sources of nutrient pollution, potential harmful algal bloom risk, and lead to a better overall understanding of the health of the Hudson River estuary and its tributaries.
Building on input from our Hudson River Water Quality Monitoring Collaborative, Riverkeeper has also added monitoring of more physical and chemical information to tributary locations. In 2026, we monitored eight tributaries sites for enterococcus, as well as four of those for E. coli, pH, temperature, conductivity, turbidity, dissolved oxygen, chlorophyll and phycocyanin (measures of algae and cyanobacteria), nutrients, and chloride. This new information will shed light on water quality in important tributaries, especially those near the location of the unprecedented harmful algal bloom in 2025. Measuring chloride will also help us to understand how road salt is impacting these tributaries.
Our monitoring program targets sites that help us to understand water quality in drinking water source areas, recreational areas, disadvantaged or overburdened communities, and places where climate change impacts our river. These sites and the data we gather help us to understand the health of the Hudson and identify risks to human and environmental health.
This year from May to October we took measurements at 253 locations: 123 sites in the mainstem of the Hudson River and 130 sites in tributaries.
In total, Riverkeeper and our partners collected over 1,600 water samples and took more than 15,000 measurements, an approximately 50 percent increase in the number of measurements we took in 2025, and a 134 percent increase since 2024.
This year we continued our partnership with multiple academic institutions, including:
- Syracuse University to look at micropollutants and precursors to disinfection byproducts throughout the Hudson River estuary. Together, we studied areas that influence drinking water intakes for the Hudson 7, the communities that get their drinking water from the Hudson River.
- Hudson Valley Community College to continue their study of microcystin (a toxic byproduct of harmful algal blooms) dynamics in the Hudson River.
- Vassar College to take samples at Chodikee Lake and better understand water quality and the influence of the lake on Black Creek.
Riverkeeper’s water quality monitoring program is a key pillar of our work, providing the data-based foundation that informs our advocacy and legal actions to protect for clean water. We will continue to explore partnerships, new sites, and additional measurements that will help us evaluate pollution, respond to new and emerging threats, and protect the Hudson River and its tributaries now and for generations to come.
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