FoHVOS, Princeton Hydro Launch Study to Predict Harmful Algal Blooms
Friends of Hopewell Valley Open Space (FoHVOS), in partnership with the ecological engineering consulting firm Princeton Hydro, has launched a groundbreaking initiative, “Monitoring Harmful Algal Blooms (HABs) in the Delaware River Watershed Using Drones and Spatial Analysis,” to improve understanding and forecasting of HABs throughout the Delaware River Watershed.
Funded by the National Fish and Wildlife Foundation (NFWF), in partnership with the U.S. Fish & Wildlife Service, through the Delaware Watershed Conservation Fund (DWCF), the project leverages drone technology and advanced data modeling to identify environmental conditions that contribute to HAB formation and aims to develop tools and methodologies for early detection and management.
For this project, FoHVOS, a 501(c)3 and accredited Land Trust located in Hopewell Township, has teamed with Princeton Hydro, a water resources engineering and natural resources management small business consulting firm that conceptualized and designed the initiative. The firm is leading the technical implementation, including field survey design, drone operations, data analysis, and volunteer training.
“The Delaware River is central to Hopewell Valley’s identity. It shapes our way of life, supplies drinking water to 14.2 million people, shelters wildlife like the endangered Atlantic sturgeon, and offers abundant outdoor recreation,” said Jennifer Rogers, executive director of Friends of Hopewell Valley Open Space.
“HABs were once confined to ponds and lakes, but since 2018, they’ve appeared in colder months and spread to streams and rivers. Though land trusts traditionally focus on land, HABs show how land use directly affects water. These blooms often stem from excess nitrogen and phosphorus washed into waterways during storms. Protecting water means restoring land. Our partnership with Princeton Hydro aligns perfectly with our mission. Together, we’re working to better understand and safeguard the Delaware River and its tributaries in both NJ and PA.”
HABs, caused by nuisance growth of cyanobacteria, can have detrimental effects on water quality and are a growing environmental concern nationwide. These blooms deplete oxygen levels, release toxins, and disrupt ecosystems, potentially posing serious risks to drinking water supplies and the health of wildlife, pets, humans, and local economies. Despite advances in environmental monitoring, predicting when and where HABs will occur remains a challenge due to the complex interplay of nutrient loading, temperature, and hydrologic conditions that can lead to rapid bloom proliferation.
To address these challenges, this newly launched initiative integrates drone-based remote sensing, field sampling, and spatial data analysis to collect and interpret detailed environmental data over a two-year period. The study spans multiple monitoring sites along a 73-mile stretch of the Delaware River in New Jersey and Pennsylvania, focusing on near-shore sections and 23 associated waterbodies. The first survey event began in August 2025.
Drones equipped with multispectral imaging systems capture high-resolution spatial data that is then integrated with digital platforms to link remote-sensing with the drone data and on-the-water collected data.
The field-based water quality measurements are being collected by a team of trained community volunteers who are using phycocyanin fluorometer meters to measure concentrations of the photosynthetic pigment phycocyanin, which is produced primarily by cyanobacteria. Volunteers enter the data into a customized ArcGIS mobile-friendly survey.
These combined datasets will be used to develop and validate predictive algorithms for both planktonic and benthic HABs under varying seasonal and hydrologic conditions.
“This research project represents a major step forward in how we study and manage harmful algal blooms at the watershed scale,” said Fred Lubnow, project lead and senior technical director of ecological services at Princeton Hydro. “By integrating satellite data, drone imagery, and on-the-water sampling, we’re developing predictive tools that will enable us to take a proactive approach to mitigate HABs, improve response time, and better support our ecosystem health.”
Project partners include New York City College of Technology – The City University of New York, which donated the drone and is supporting remote sensing and data integration; Trenton Water Works, Mercer County Park Commission, and The College of New Jersey which are providing monitoring sites and contributing volunteers for water quality data collection in New Jersey; Aqua-PA and the Philadelphia Water Department, which are providing monitoring sites and volunteers to collect watershed data in Pennsylvania; the Bucks County Conservation District, which is coordinating volunteer data collection; and Turner Designs, whose advanced phycocyanin sensors are being used to calibrate and validate drone-based monitoring data.
This $1 million project is funded through a $488,400 NFWF DWCF grant as part of the NFWF’s Research, Monitoring, & Evaluation Grant category and $513,700 in matching funds from project partners. This grant category aims to support high-performing science that is inclusive, adaptive, and innovative, with the potential to transform the Delaware River Watershed’s future through improved conservation, restoration, and public engagement.
Once complete, the project will produce a comprehensive report summarizing methods, analyses, and data-driven recommendations for practical, low-cost HAB monitoring and mitigation strategies that can be replicated across the Delaware River Watershed and beyond. Crucially, the report will identify tributaries and sources contributing to riverine HABs, enabling targeted restoration of the most affected lands and waters. Data collection will continue through Fall 2025, resume in Spring/Summer 2026, and culminate in a final report expected in 2027.
Learn more at www.fohvos.org and www.princetonhydro.com.
Talk of the Sourlands: A Healthy Watershed Takes a Village
The Sourland Conservancy’s Talk of the Sourlands series concludes its season with presentation in partnership with The Watershed Institute focused on how healthy land equals healthy water.
The final talk, “A Healthy Watershed Takes a Village… and Everyone Up and Downstream of the Village,” takes place Thursday, November 13, at 7 p.m. at The Watershed Institute, 31 Titus Mill Road, Pennington. The presentation will be led by Dr. Steven Tuorto, director of science and stewardship at The Watershed Institute. Tuorto will share how land use directly impacts water quality and how regional collaboration is essential to addressing major environmental challenges such as flooding and harmful algal blooms.
“Healthy land equals healthy water,” Tuorto says. “We all play a role in how our watershed functions. Only through collaboration can we make meaningful progress toward protecting our region’s most vital natural resources.”
Attendees will gain insight into the science behind watershed health, learn about ongoing restoration projects, and discover how local action contributes to regional impact.
The event will be hybrid, with both in-person and virtual attendance options. Admission is free, but registration is required. For more information and to register for the talk, visit www.sourland.org/events.
