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From tidal estuaries and back bays to nearshore marine waters, New Jersey’s coastal environments support fisheries, recreation, wildlife, and local economies. Increasingly, however, these valuable ecosystems are vulnerable to a wide range of harmful algal blooms (HABs). While algae are a natural and essential part of aquatic ecosystems, certain environmental conditions can cause some species to grow excessively, leading to ecological damage, public health risks, and economic losses.
Understanding what HABs are, what drives them, and how nature‑based restoration strategies can prevent or mitigate blooms is essential to supporting the long‑term resilience of New Jersey’s coastal environments.
The term "algae" is ecological rather than taxonomic and encompasses a diverse group of organisms, including eukaryotic algae, such as diatoms and dinoflagellates, and prokaryotic cyanobacteria, commonly referred to as blue‑green algae. Algae are not inherently harmful. In fact, they provide critical ecosystem services, including:
Phytoplankton are microscopic, free‑floating algae found in freshwater, estuarine, and marine environments. Scientists estimate there are 20,000 to more than 100,000 phytoplankton species, but only a small fraction—roughly 100 to 300 species—are capable of forming toxin‑producing harmful algal blooms. Problems arise when these species proliferate rapidly under favorable conditions. These blooms can become harmful when they produce toxins, deplete oxygen, shade submerged vegetation, or otherwise disrupt ecosystem function.
While most harmful algal blooms are caused by phytoplankton, large, fast‑growing macroalgae can also create serious environmental and economic challenges when conditions allow them to proliferate. A well‑known example is Sargassum, a floating seaweed that can form extensive mats across the ocean surface. During periods of rapid growth, these mats can block sunlight from reaching coral reefs and other sensitive habitats. When Sargassum washes ashore in large quantities, it can deter tourism and recreation. As the algae decomposes, it releases hydrogen sulfide gas, producing strong odors that make nearby coastal areas unpleasant to visit. While Sargassum blooms occur most summers along the coast of south Florida, the severity and extent of these events vary considerably from year to year.
HABs can form in freshwater systems, brackish estuaries, and coastal marine waters, and they are particularly dangerous with myriad when they produce toxins that affect humans, pets, livestock, fish, shellfish, and wildlife.
Below is a closer look at the dominant types of marine HABs in the region, the organisms responsible, and the environmental conditions that influence their development.
Brown tides are associated with several diatom genera, such as:
These blooms are influenced by a combination of physical, chemical, and climatic factors, including:
Ulva, commonly known as sea lettuce, is a green macroalga that can form extensive blooms in shallow, nutrient‑rich estuaries. Another common bloomer, Enteromorpha, is now considered genetically equivalent to Ulva. Although Ulva blooms are non‑toxic, they can still cause serious ecological and social impacts:
Cyanotoxins should not be confused with taste‑and‑odor (T&O) compounds. Cyanotoxins are colorless, tasteless, and odorless whereas T&O compounds, such as geosmin and MIB, cause earthy or musty smells. Cyanobacteria can produce T&O compounds without toxins as well as toxins without noticeable odors.
This distinction can complicate detection and public perception of risk.
These HABs, the region's most common, illustrate the wide range of organisms, toxins, and ecological pathways through which algal blooms can affect coastal systems. Although they differ in form, from microscopic phytoplankton to expansive mats of macroalgae, they are often driven by a common set of environmental conditions that favor rapid growth and persistence. Climate change is intensifying many of these drivers. Rising water temperatures, altered precipitation patterns, and longer periods of stratification increasingly create conditions that favor bloom formation. At the same time, human activities continue to increase excess nutrients to coastal waters. Runoff from agricultural lands, chemicals transported by rainfall and irrigation, and discharges from wastewater treatment facilities all introduce nitrogen and phosphorus into rivers, lakes, and estuaries. These nutrients act as fertilizer for algae, accelerating bloom development.
Nutrient‑laden stormwater runoff does not remain localized, rather, it moves downstream through interconnected watersheds, ultimately reaching estuaries and coastal waters where it can contribute to marine blooms. Understanding these linkages between land use, climate, and algae growth is critical to identifying effective strategies for preventing and managing HABs in coastal environments.
Nutrient-driven water quality impairments, particularly harmful algal blooms (HABs), continue to challenge lake managers, municipalities, and watershed organizations across the Northeast. Excess phosphorus and nitrogen can rapidly degrade ecological conditions, limit recreational use, impact sources of potable water, and increase management costs, often despite the implementation of conventional best management practices. As a result, there is growing interest in tools that can complement or augment existing approaches and address nutrients in more targeted ways.
Biochar has emerged as one such tool. While it is best known as a soil amendment, its physical, chemical, and biological properties have prompted increasing use in aquatic systems as a means of improving water quality. Over the past five years, Princeton Hydro has applied biochar in a range of lakes, ponds, streams, and stormwater-related settings across Pennsylvania, New Jersey, and New York. These field applications, supported by monitoring, have provided important insight into when biochar is most effective, where its limitations lie, and why observed improvements in water quality are not always explained by phosphorus removal alone.
Biochar is a carbon-rich, charcoal-like material produced through pyrolysis, a process in which organic biomass is heated in a low-oxygen environment. The resulting material has a highly porous structure and extensive surface area, properties that make it effective at adsorbing nutrients such as phosphorus and nitrogen (Joseph et al., 2021). Because excess nutrients are a primary driver of eutrophication and HABs, biochar has emerged as a promising amendment for aquatic systems and stormwater best management practices (BMPs).
In aquatic applications, biochar is typically installed in permeable sleeves (aka socks) or incorporated into stormwater treatment practices to intercept nutrient-rich water before it enters lakes or ponds. Used biochar can also be repurposed as a soil amendment, adding to its appeal as a sustainable, circular material.
Through approximately half a dozen monitored projects implemented since 2020, several consistent patterns have emerged.
Standing Waters Show the Strongest Response: Biochar has proven most effective in low-flow or standing water environments such as ponds and stormwater basins. In these systems, Princeton Hydro has documented total phosphorus (TP) removal rates as high as 80%, with soluble reactive phosphorus (SRP) reductions approaching 97% in some stormwater ponds (Princeton Hydro, Lake Hopatcong Report, 2022). The extended contact time between water and biochar in these settings appears to be a key driver of performance.
Flow and Contact Time Matter: In streams and fast-moving stormwater infrastructure, nutrient removal rates tend to be lower, with phosphorus reductions typically closer to 50%. While still meaningful, these reduced efficiencies are largely attributable to limited contact time. Simply put, the shorter the interaction between water and biochar, the fewer opportunities there are for adsorption and other removal processes to occur.
Enhancement to Conventional Stormwater BMPs: Biochar can be particularly effective when paired with stormwater BMPs that primarily rely on sedimentation. Traditional practices often excel at removing particulate-bound phosphorus but are less effective at capturing dissolved forms of phosphorus—the fraction most readily utilized by algae. Incorporating biochar into these systems can enhance removal of dissolved phosphorus, improving overall treatment performance.
Streams Present Physical Challenges: Installing biochar in stream environments presents practical challenges. Even with careful anchoring, large storm events, including remnants of hurricanes, can dislodge biochar sleeves, transporting them downstream or onto streambanks. These risks must be considered during design and often limit the suitability of biochar for higher energy systems.
Chemistry Alone Does Not Tell the Whole Story: At very high pH levels, phosphorus adsorption onto biochar can become less predictable, sometimes exhibiting a “decoupling” between measured phosphorus sorption and observed water quality improvements. Monitoring data from multiple projects indicate that reductions in chlorophyll-a, cyanobacteria abundance, and overall bloom severity cannot always be explained by phosphorus removal alone.
The disconnect between measured nutrient sorption and improved water quality suggests that additional mechanisms are at work. Increasingly, evidence points toward biological processes occurring within and around biochar installations.
Biochar is known to favor the growth and proliferation of heterotrophic bacteria (Moore et al., 2023). These microbial communities may contribute to water quality improvements in the following ways:
This emerging science mirrors what Princeton Hydro has observed in the field: water quality can improve in ways that chemical measurements alone do not fully explain, suggesting that biological processes may be playing an important supporting role.
Since 2020, Princeton Hydro has applied biochar across a range of aquatic and stormwater settings, tailoring each installation to site-specific conditions and management goals. Together, these projects demonstrate biochar’s versatility and its ability to integrate into holistic watershed and lake management strategies, often working best when paired with other nature-based and engineered solutions.
At Duke Farms, a 2,700-acre estate in New Jersey, Princeton Hydro has supported lake and wetland management efforts for more than two decades. Biochar was recently introduced as an additional tool within an established, science-based nutrient management program. By placing biochar in low-flow areas where contact time could be maximized, phosphorus removal was enhanced and improvements in water clarity were observed. This effort highlights how biochar can be layered into long-term management strategies alongside floating wetland islands and other nature-based solutions.
Harvey’s Lake, the largest natural lake in Pennsylvania, has long faced challenges associated with nutrient loading and recurring HABs. As part of a broader stormwater management effort, Princeton Hydro incorporated biochar into select stormwater BMPs to reduce phosphorus before it entered the lake. Installed within targeted stormwater conveyance and treatment features, the biochar helped achieve measurable reductions in dissolved phosphorus, complementing other watershed-scale measures such as vegetated buffers and wetland enhancements. The spent biochar, having captured phosphorus and nitrogen from runoff, was then repurposed as a soil amendment to enrich a 500-square-foot pollinator garden. This repurposing effort served a dual purpose: demonstrating a closed-loop approach to managing excess nutrients while also creating a community-oriented space that supports local biodiversity.
Across multiple stormwater projects in New Jersey and Pennsylvania, biochar has been installed in detention basins, rain gardens, and other stormwater treatment devices. These applications were designed to target dissolved phosphorus, a nutrient form that conventional BMPs can struggle to remove. In several cases, biochar was paired with other nutrient control measures such as floating wetland islands to further improve nutrient capture. Collectively, these projects illustrate how biochar can be adapted and scaled to address local water quality challenges across diverse settings.
At Lake Hopatcong, New Jersey’s largest lake, biochar was deployed as part of a comprehensive, multi-pronged strategy to reduce nutrient concentrations and mitigate HABs. Biochar was installed in permeable flotation bags and placed at targeted shoreline and inlet locations where nutrient loading is most pronounced, including several stormwater inlets and outlets around the lake. Funded through the NJDEP Freshwater HABs Prevention & Management Grant Program and implemented in partnership with the Lake Hopatcong Commission and the Lake Hopatcong Foundation, these installations complemented other in-lake management measures such as floating wetland islands.
In Manhattan's Central Park, Princeton Hydro supported the Central Park Conservancy in developing and implementing a long-term management strategy for the park's network of lakes and ponds, where harmful algal blooms driven by excess nutrients were a persistent concern. As part of a broader, phased approach to improve water quality, biochar was incorporated as a nutrient reduction tool and will be incorporated alongside other measures such as floating wetland islands, aeration and circulation, and stormwater treatment techniques. Used in targeted locations, biochar helped support efforts to reduce nutrient loading and mitigate cyanobacteria blooms within these highly visible urban waterbodies.
Across these projects, biochar installations have been associated with measurable reductions in total and dissolved phosphorus, decreases in chlorophyll‑a concentrations, and lower cyanobacteria cell counts. While performance has varied by site, the strongest and most consistent results have occurred in enclosed or low‑flow environments where contact time is maximized and physical disturbance is minimized. When thoughtfully designed and integrated with other BMPs, these case studies show how biochar can contribute meaningfully to broader efforts to reduce nutrient loads and improve overall water quality.
Biochar is not a one-size-fits-all solution. Reviewing site-specific water quality data is essential to determine whether biochar is an appropriate standalone treatment or should be combined with complementary approaches. Ongoing and future research is focused on better quantifying the relative contributions of chemical adsorption and biological activity associated with biochar. Current studies, including collaborative efforts with academic partners, aim to document pollutant removal capacity, characterize microbial communities, and evaluate biochar’s potential role in degrading cyanobacteria and cyanotoxins. As these processes continue to be studied and further understood in the water quality context, biochar may become an increasingly valuable component of integrated, science-based watershed management strategies.
Dr. Fred Lubnow, Princeton Hydro's Senior Technical Director of Ecological Services, and Jenn Rogers, Executive Director of Friends of Hopewell Valley Open Space (FoHVOS), were recently featured on the Native Plants, Healthy Planet podcast to discuss the collaborative, first‑of‑its‑kind initiative to monitor Harmful Algal Blooms (HABs) in the Delaware River Watershed using drones, spatial analysis, and community science.
The Delaware River is a lifeline for more than 14 million people, a refuge for wildlife, and a defining natural feature of the region. In recent years, HABs, once confined mostly to lakes and ponds, have expanded into streams and rivers and appearing in colder months. Understanding why this shift is happening, and how to predict it, is essential for protecting water quality, public health, and ecological resilience within the Delaware River watershed and watersheds nationwide.
The podcast, hosted by Fran Chismar and Tom Knezick of Pinelands Nursey, highlights the urgency of addressing HABs and the innovative, cross‑sector partnership driving this work forward. Listen now: Harmful Algal Blooms with Dr. Fred Lubnow and Jenn Rogers.
Jenn Rogers, Executive Director of FoHVOS, brings two decades of conservation leadership to the partnership. Her background spans naturalist education, ecological stewardship, and the development of large-scale restoration and public engagement programs. During her fourteen years with the Mercer County Park Commission, she helped establish both the Environmental Education and Stewardship Departments and oversaw the care of more than ten thousand acres of parkland.
Jenn has spent her career building programs that connect people to the landscapes around them. Her commitment to community-driven conservation make her a key partner in a project that relies on both scientific rigor and public participation. Her perspective highlights how land use, watershed health, and community stewardship are deeply interconnected.
Dr. Fred Lubnow serves as Princeton Hydro’s Senior Technical Director of Ecological Services and brings more than 30 years of experience in limnology, watershed restoration, and community and ecosystem ecology. His career has focused on understanding how freshwater systems respond to nutrient loading, hydrologic change, and long-term environmental pressures. He has designed and led numerous lake and watershed restoration projects, developed USEPA Nine-Element and TMDL-driven watershed plans, and created field-based cyanobacteria and cyanotoxin monitoring programs that are now used across the region.
Fred’s expertise in the taxonomy, ecology, and management of algae, particularly cyanobacteria, has made him a leading voice in the study of HABs. He currently serves on New Jersey’s HABs Advisory Team, where he helps interpret water quality data and advises on mitigation strategies. His scientific leadership guides the technical design and implementation of the Delaware River HAB monitoring initiative.
Now entering its second year, the Delaware River HAB monitoring initiative is expanding both its scientific scope and its community engagement efforts. Building on the foundation established in 2025, the project team is conducting multi‑season drone flights, enhanced satellite‑based surveys, and targeted on‑the‑water sampling along 73 miles of the Delaware River and 24 connected waterbodies. These efforts are designed to strengthen the project’s ability to detect and forecast HABs under a wide range of seasonal and environmental conditions.
Year two also introduces several tools and activities intended to support broader participation and more efficient data collection. This includes the launch of a new ArcSurvey123 mobile data platform to support real‑time volunteer water quality submissions, as well as expanded training opportunities for community members interested in assisting with field sampling. Data collected through these efforts will contribute to the development of advanced algorithms capable of forecasting HAB occurrence at multiple spatial scales.
Funded by the National Fish and Wildlife Foundation's (NFWF) Delaware Watershed Conservation Fund (DWCF), in partnership with U.S. Fish & Wildlife Service, the project continues to be supported by a diverse network of partners across New Jersey and Pennsylvania, including The City University of New York's (CUNY) New York City College of Technology (City Tech), Trenton Water Works, Mercer County Park Commission, The College of New Jersey, Aqua-PA, Philadelphia Water Department, Bucks County Conservation District, Turner Designs, and US Army Corps of Engineers - Philadelphia District's Blue Marsh Lake. Together, these organizations contribute technical expertise, watershed knowledge, and crucial on‑the‑ground support. This collaborative approach remains central to the initiative’s success and long‑term objective: establishing a scalable HAB‑forecasting framework that can ultimately be applied to additional watersheds across the United States.
For a deeper look at the research, partnerships, and shared commitment behind this initiative, listen to the full Native Plants, Healthy Planet podcast presented by Pinelands Nursery. Click here to learn more about the Pinelands Nursery and explore the full library of Native Plants, Healthy Planet podcasts. If you're interested in getting involved in the Delaware River HAB research initiative, the program is currently seeking volunteers for water sampling along the Delaware and select waterbodies. Contact FoHVOS Conservation Biologist Kaitlin Muccio at: kmuccio@fohvos.org for more details.
On February 12, Princeton Hydro Senior Wildlife Biologist Mike McGraw, CSE, QAWB, ACE joined Bird Town Pennsylvania for a virtual Zoom workshop titled “A Wholistic Approach to Managing Residential and Park Scale Habitats for Rare and Common Bird Species.” The talk brought together ecological science, practical land‑stewardship guidance, and a powerful call to reimagine how communities support thriving bird populations across Pennsylvania and beyond.
Bird Town PA’s Education Committee hosted the webinar as part of its ongoing effort to connect residents, landowners, and municipal leaders with science‑based strategies that enhance local biodiversity. Their mission, centered on community education, habitat conservation, and sustainable landscaping, aligned seamlessly with the themes Mike explored throughout the presentation.
To help extend the reach of this insightful discussion, we’ve collected highlights from the workshop and invite you to watch the full presentation:
Mike’s presentation provided a comprehensive look at the ecological principles behind bird behavior, the habitat features that sustain both common and rare species, and the steps landowners and municipalities can take to strengthen biodiversity within residential and park‑scale landscapes. He wove together life‑history science, soil and plant ecology, practical stewardship strategies, and community‑based conservation approaches to illustrate how thoughtful land management can meaningfully support bird populations across Pennsylvania.
He emphasized that all wildlife depends on very specific combinations of biotic and abiotic conditions, meaning that changes in habitat structure, vegetation, soils, and climate directly influence which species can persist in a landscape.
To illustrate this, Mike walked attendees through:
By examining real examples of species and their migratory behaviors, Mike demonstrated how the presence (or absence) of certain bird species can serve as a diagnostic indicator of habitat function and ecosystem health, revealing signs of environmental stress, habitat fragmentation, and the impacts of climate change.
Mike outlined the fundamental elements birds need to thrive, including food, water, shelter, mates, and protected nesting or rearing spaces, and demonstrated how providing these through intentional plant selection, structural habitat diversity, and management practices rooted in natural processes results in predictable increases in wildlife use.
He paired these concepts with a practical decision‑making framework for landowners and municipalities, encouraging them to understand soils as living systems, increase plant diversity, and use ecological tools such as USDA zones and native plant lists to guide planning. Mike also highlighted the important role residential and municipal landscapes can play in supporting rare and declining bird species, offering real‑world examples and resources to help translate ecological principles into effective habitat improvements.
Access to nature is a fundamental right, and every community has the power to help shape a healthier ecological future. With this message in mind, Mike outlined a variety of ways residents and municipalities can support bird species of greatest conservation need, including implementing building standards that incorporate bird-safe features, expanding education on responsible pet practices such as keeping cats indoors, ensuring feeding stations remain clean, and adding decals to windows around the home to prevent bird strikes. He emphasized the importance of expanding and enhancing public parks and green spaces, particularly in underserved areas, and supporting programs that foster stronger connections between people and the natural world.
Mike McGraw is a Certified Senior Ecologist and Wildlife Biologist with more than 20 years of experience conducting ecological assessments, wildlife surveys, and conservation-focused research across the United States and Canada. His work spans ecological restoration, regenerative agriculture research, and master planning for large landscapes. He teaches Avifaunal Ecology at the University of Pennsylvania and serves on several municipal and land trust committees. Some of Mike’s research on regenerative agriculture has been documented in film.
The webinar was hosted by the Bird Town PA Education Committee of Bird Town Pennsylvania, LLC. Bird Town PA partners with communities to promote sustainable practices, habitat conservation, and public education aimed at supporting Pennsylvania’s bird species. Through workshops, citizen science initiatives, and municipal programs, they empower people to make informed decisions that benefit both wildlife and human well-being. Learn more at birdtownpa.org.
Our team participated in a special community screening of the 4-part docuseries, "Roots So Deep (You Can See the Devil Down There)" at the historic Newtown Theatre in Pennsylvania. As one of the country’s oldest continuously operating theaters, the venue provided a meaningful setting for a film centered on heritage, land stewardship, and community. People throughout the region gathered to explore how regenerative grazing can restore soils, support wildlife, and strengthen the resilience of working farms. The event was co-hosted by Newtown Theatre, Bowman's Hill Wildflower Preserve, and Pinelands Nursery.
"Roots So Deep" follows farmers and researchers across the country as they test adaptive multi-paddock (AMP) grazing and measure its ecological impacts. This method mimics the way bison once roamed the land. The film explores themes of soil health, biodiversity, and the value of collaborative land management. Can AMP grazing can help farmers reduce costs by not buying fertilizer, restore depleted soils, rebuild wildlife habitat, and capture carbon?
At the center of the evening was Princeton Hydro Senior Wildlife Biologist Michael McGraw, CSE, QAWB, and ACE, who appears in the documentary for his work studying breeding bird populations in AMP grazed landscapes. His research examines how breeding bird communities differ between paddocks managed with AMP grazing and those that are continuously grazed. The film emphasizes that when grazing is managed thoughtfully, farmland can support both agricultural productivity and ecological benefits, including healthier wildlife populations.
After the screening, Mike participated in a Q and A session and shared insights from his fieldwork. He discussed how grazing practices shape habitat quality and influence wildlife communities, and he answered a range of questions from attendees who were eager to learn about the ecological implications of AMP systems.
Mike was joined by two regional partners. Fran Chismar from Pinelands Nursery contributed perspectives from the native plant restoration community. Fran also co-hosts the podcast Native Plants, Healthy Planet, which is recognized as a top 20 nature podcast and serves as an important platform for discussions on conservation and ecological stewardship. Santino Lauricello, representing Bowman’s Hill Wildflower Preserve, added context through his expertise in native flora and conservation education. Together, their voices reinforced the collaborative spirit that drives ecological work forward.
As the conversation between Mike, Fran, Santino, and the audience began to take shape, the tone was warm, thoughtful, and deeply engaged. Members of the audience responded to the film’s themes with genuine curiosity, asking questions that reflected a sincere interest in the ecological studies presented throughout the documentary. Their enthusiasm created a sense of shared purpose, highlighting a collective desire to support healthier ecosystems and continue learning from the research behind regenerative grazing.
Even if you weren’t able to join us for the screening, you can still be part of the ongoing conversation. The trio came together on the Native Plants, Healthy Planet Podcast for a special Roots So Deep recap episode, where they explored Mike’s involvement in the project, generational shifts in family‑run agricultural operations, and reflections from the live Q&A at the Newtown Theatre. The podcast provides a meaningful way to revisit the insights from the event and continue exploring the themes of regenerative grazing and ecological restoration. Listen now: Roots So Deep with Mike McGraw and Santino Lauricella
We are grateful to the Newtown Theatre, the event organizers, and the conservation partners who helped bring this screening to life. Gatherings like this illustrate the power of bringing science and storytelling together, creating space for communities to learn, reflect, and connect.
If Roots So Deep resonated with you or sparked your curiosity about regenerative grazing and ecological research, we encourage you to continue exploring the film’s themes, follow upcoming screenings, and stay connected with the conversations it inspires. Your interest and engagement help support the momentum behind this important work. If you're a farmer looking to switch to AMP grazing and want to measure the impact, we'd be happy to talk with you about how to get started. Send us a message.
Friends of Hopewell Valley Open Space (FoHVOS), in partnership with 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 innovative research project, FoHVOS, a 501(c)3 and accredited Land Trust located in Hopewell Township, NJ, has teamed with Princeton Hydro. Princeton Hydro conceptualized and designed the initiative and 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 FoHVOS. “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.
The following photos depict the RGB (Visual) and corresponding Thermal image from the monitoring flights over Spring Lake in New Jersey:
“This research project represents a major step forward in how we study and manage harmful algal blooms at the watershed scale,” said Dr. 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 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.
In the photos below, volunteers are being trained by Princeton Hydro staff on how to use phycocyanin fluorometers and Secchi disks to gather water quality data and log their findings.
This $1M 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.
FoHVOS is a 501(c)3 nonprofit land trust dedicated to conserving the natural resources of the Hopewell Valley region and beyond. Through land preservation, ecological restoration, community engagement, and science-driven initiatives, FoHVOS works to protect and enhance open spaces for future generations. Learn more at www.fohvos.org.
Princeton Hydro is committed to improving our ecosystems, quality of life, and communities for the better. The firm was formed in 1998 with the specific mission of providing integrated ecological and engineering consulting services. Offering expertise in natural resource management, water resources engineering, geotechnical design and investigation, and regulatory compliance, their staff provide a full suite of environmental services throughout the Northeast for the public and private sectors. Project Lead, Dr. Fred Lubnow, is an expert in HAB management and has worked with dozens of lake associations and government agencies to restore lakes, manage watersheds, reduce pollutant loading, address invasive aquatic plants, and mitigate nuisance HABs. To learn more about Princeton Hydro's work to mitigate harmful algal blooms, go here.
The Lower Darby Creek Area encompasses a unique blend of residential neighborhoods, commercial zones, and critical regional infrastructure, including the Philadelphia International Airport, Interstate 95, and portions of the John Heinz National Wildlife Refuge. Despite its urban setting, the area supports diverse wetlands, waterways, and wildlife habitats that play an essential role in regional flood protection, resiliency, and ecological connectivity.
Flooding and habitat loss have long challenged the Lower Darby Creek Area, particularly in the communities of Eastwick in southwest Philadelphia and Tinicum Township of Delaware County, PA. Residents in these neighborhoods experience extreme flooding during storm and high tide events, and community groups have been leading local efforts to enhance resilience and reduce flood risk. The increasing effects of climate change, such as more intense storms, sea level rise, and frequent tidal flooding, are compounding challenges.
To help address these challenges, The Nature Conservancy in Pennsylvania (TNC) and the John Heinz National Wildlife Refuge have commissioned Princeton Hydro to lead a two-year Urban Flood and Habitat Resilience Feasibility Study for the Lower Darby Creek Area. The study aims to identify and evaluate nature-based solutions that would help to convey, store, and infiltrate water to alleviate flooding, improve habitat for local wildlife species, and enhance community resilience.
Community engagement is a cornerstone of the Feasibility Study, ensuring that local voices help shape the region’s path toward long-term resilience. The project work began with a series of community meetings to learn from residents about the impacts of flooding and the changes they want to see in their neighborhoods. The outcome of this project will be a list of 6-10 nature-based solutions that have been prioritized by community members and that have been analyzed for feasibility and potential for flood reduction and ecological benefit. This information will be presented in a Project Roadmap for the co-developed pathway to achieve community and ecological resilience through project implementation. This guidance will empower partners and communities to secure funding, implement pilot projects, and advance long-term resilience goals.
Once the study is complete, Princeton Hydro will create an interactive ArcGIS StoryMap webpage that will allow users to take a deeper dive into the study's findings and interact with the data. Users will be able to visualize flood scenarios and potential restoration opportunities and learn more about specific project activities and the proposed solutions.
Earlier this year, project partners joined residents for Eastwick Community Day, a vibrant event celebrating neighborhood connections, local leadership, and climate resilience. Hosted by the City of Philadelphia’s Office of Sustainability, the event was supported by representatives from The Nature Conservancy in Pennsylvania, John Heinz National Wildlife Refuge, and Princeton Hydro, including Director of Restoration & Resilience Christiana Pollack, CERP, CFM, GISP and Director of Aquatics Mike Hartshorne.
The gathering offered residents an opportunity to meet the organizations involved in the flood study, learn about available climate resilience resources, and share their own experiences and priorities. Alongside informational displays and project updates, attendees enjoyed a picnic lunch, family activities, and hands-on learning about nature-based solutions. It was a day that captured the spirit of collaboration driving this initiative.
The Lower Darby Creek initiative builds on Princeton Hydro’s earlier Eastwick Flood Resilience Study, expanding from a neighborhood-focused analysis to a watershed-scale approach. In 2016, in partnership with the University of Pennsylvania, the John Heinz National Wildlife Refuge, Keystone Conservation Trust, Audubon Pennsylvania, and the William Penn Foundation, Princeton Hydro conducted an analysis of Eastwick, the flood impacts created by the Lower Darby Creek, and the viability of several potential flood mitigation strategies. The study sought to answer questions commonly asked by community members related to flooding conditions, with the main question being: What impact does the landfill have on area flooding? Princeton Hydro developed a 2-D hydrologic and hydraulic model to understand how varying restoration techniques, including removal of the Clearview Landfill, expansion of the existing tidal freshwater wetland, removal of bridge infrastructure, and rerouting storm flows, would alter flooding in the Eastwick neighborhood.
Findings from that study provided key data and analytical frameworks that now inform the Lower Darby Creek Area Feasibility Study. Expanding beyond the boundaries of Eastwick, the comprehensive Lower Darby Creek Area study takes a watershed-scale view, exploring how interconnected systems, including upstream hydrology, tidal influences, and habitat networks, can be managed holistically.
Resilience is not achieved in isolation; it thrives through collaboration. The success of the Lower Darby Creek Area Feasibility Study and related restoration projects depends on a network of partners committed to shared goals. By aligning expertise, resources, and local knowledge, these partnerships create a foundation for long-term climate adaptation and ecological health. To learn more about the Nature Conservancy in Pennsylvania, click here. To learn more about the City of Philadelphia Office of Sustainability Flood Resilience Strategy for Eastwick, go here. And, click here to learn more about the John Heinz National Wildlife Refuge in Tinicum.
Princeton Hydro is also collaborating with the Refuge to restore the Refuge’s Turkey Foot area. Working with Enviroscapes and Merestone Consultants, our team designed and implemented habitat enhancement and hydrologic restoration projects to improve water quality, restore native wetland vegetation, and expand habitat for fish and wildlife. If you’re interested in learning more about this project, check out our blog: Ecological Restoration in John Heinz National Wildlife Refuge.
This summer, Princeton Hydro aquatic scientists joined forces with Billion Oyster Project and AKRF on an exciting effort to better understand how restored oyster reefs are supporting life in New York City’s waterways. The project, “Monitoring of Mobile Estuarine Organisms at Restored Oyster Reefs,” focuses on tracking fish, crabs, snails, and other aquatic species that call these reefs home, as well as using cutting-edge environmental DNA (eDNA) techniques to detect organisms that might otherwise go unnoticed.
As a consultant to AKRF, our team deployed collection gear across current and potential restoration sites, including Brooklyn Bridge Park, Bush Terminal Park, Flushing Bay, and Paedergat Basin. The sampling enclosures, left in the water for 48 hours, revealed a fascinating snapshot of estuarine life, from small schooling fish to a surprise dogfish, a small shark-like species that was one of the highlights of the summer survey sessions.
This collaborative initiative brings together multiple partners: Billion Oyster Project, the driving force behind large-scale oyster reef restoration in New York Harbor, is leading the project. AKRF, headquartered in New York City, is serving as the primary consultant; Princeton Hydro is leading the mobile estuarine sampling efforts and eDNA sample collection; and Monmouth University is analyzing the eDNA samples to help identify species present at the restoration sites.
Oyster reefs are living structures that provide essential habitat for a wide array of species, improve water quality through natural filtration capabilities, and enhance the resilience of New York Harbor against coastal storms and erosion. Monitoring oyster reefs ensures that restoration efforts are successful and helps scientists refine approaches for scaling up oyster reef projects in urban estuaries locally and throughout the world.
As the field sampling lead, Princeton Hydro completed two monitoring and sampling collection events, one this Spring and one this Summer, at the various oyster reef restoration sites. Using sea bass and minnow collection gear, our team - Jesse Smith, Aquatic Ecologist; Jackson Tilves, Staff Scientist; and Kaitlyn Jones, Staff Scientist - identified, measured, and documented each of the found species before safely returning them to the water. In addition, we collected in-situ water quality data at each site to help interpret how environmental conditions influence reef communities.
Our team brings deep experience and specialized equipment to this project. Princeton Hydro’s biologists have conducted estuarine surveys throughout the Hudson River and New York Harbor, led nekton and benthic sampling along New Jersey’s coastline, and carried out numerous studies that inform restoration and resilience efforts across the region.
Alongside traditional monitoring, the “Monitoring of Mobile Estuarine Organisms at Restored Oyster Reefs” project uniquely incorporates eDNA sampling. eDNA is genetic material that organisms shed into their surrounding environment, through skin cells, mucus, or waste, that can be detected in water samples. By collecting and analyzing eDNA, scientists can identify the presence of species that may not appear in sampling enclosures. The analysis provided by the team at Monmouth University helps paint a fuller picture of biodiversity at the restored oyster reef sampling locations.
The photos below capture moments from the field and the diverse aquatic life our team encountered, offering a glimpse into the many species that oyster reefs help support in the New York Harbor:
Founded in 2014, Billion Oyster Project is working to restore one billion oysters to New York Harbor while engaging New Yorkers directly in the process. Oyster reefs once covered hundreds of miles of shoreline, filtering water, creating habitat, and buffering against storm surge. Today, Billion Oyster Project’s mission is not only to restore these vital ecosystems but also to inspire lasting stewardship of them through educational programming and free STEM curricula for NYC schools and educators . To learn more about Billion Oyster Project and how to participate, click here.
Princeton Hydro is proud to partner with Billion Oyster Project, AKRF, and Monmouth University on this project and in the advancement of urban reef restoration. Together, we’re building knowledge that informs the future of oyster reefs in New York Harbor while strengthening ecological health and resilience of the city’s waterways for generations to come.
To learn more about our work to restore New York’s waterways, we invite you to read our Client Spotlight blog featuring Riverkeeper, a 501(c)3 nonprofit membership organization committed to protecting and restoring the Hudson River from source to sea and safeguarding drinking water supplies through advocacy rooted in community partnerships, science, and law.
Coastal communities are on the frontlines of climate change, facing rising seas, stronger storms, and eroding shorelines. At the same time, these landscapes provide critical habitat and natural defenses that protect people, ecosystems and myriad wildlife. Coastal ecological restoration restores natural systems and strengthens future resilience to climate impacts.
Earlier this month, our team joined the New Jersey Coastal Resilience Collaborative (NJCRC) for its Coastal Ecological Restoration Technical Workshop, a full-day, in-person event held at the Rutgers EcoComplex in Bordentown, NJ. The workshop convened coastal stakeholders, researchers, practitioners, and managers to share knowledge and explore the latest science advancing coastal ecological restoration.
The day began with a work group session, “Advancing Science-Based Ecological Restoration Across New Jersey’s Coast,” led by a panel of experts and followed by an interactive Q&A. Click here to view the presentation. Participants then chose from a variety of technical sessions covering topics such as, eDNA and Water Quality as Indicators of Coastal Ecological Health; Smart Permitting for Restoration; and Diatoms as Ecological Indicators in Living Shoreline Applications.
Dana Patterson Grear, Princeton Hydro's Director of Marketing & Communications, delivered an engaging presentation titled, "How to Build a Digital Communications Toolkit for Climate Action." She provided practical guidance for turning communication into a powerful tool for advancing ecological restoration and climate resilience, including how to develop tailored climate messaging, understand the values of your audience and remove personal bias, and determine your level of engagement and capacity. Dana's presentation broke down complex communication strategies into actional steps that attendees can apply directly to their work. Click here to view her presentation slides.
Beyond the educational workshops, networking breaks, shared meals, and a post-workshop reception created opportunities to connect and collaborate. And, as a fun and fitting bonus, each participant went home with a complimentary native plant courtesy of Pinelands Nursery.
Coastal ecological restoration involves the rehabilitation and creation of coastal ecosystems, like wetlands, reefs, and shorelines, with the goal of restoring the natural processes and functions. These efforts provide long-term protection from erosion, create habitat for fish and wildlife, and build community resilience against flooding and storm surge.
At Princeton Hydro, we understand the impacts of climate change, including sea level rise, and use tools such as vulnerability assessments to inform our restoration designs. Our team specializes in designing and implementing living shorelines and habitat restoration projects. We combine field data, empirical approaches, ecological and geomorphic understanding, hydrologic and hydraulic modeling, and state-of-the-art computer programming technology to develop our designs. Our nature-based solutions deliver lasting ecological and community benefits.
A prime example of this work is the Spring Creek North Ecosystem Restoration project, located in Brooklyn and Queens, NY. Once part of the expansive Jamaica Bay wetland system, Spring Creek's salt marshes were heavily degraded over the last century. Princeton Hydro was contracted by the U.S. Army Corps of Engineers, New York District to lead the design and engineering for this restoration effort. Construction efforts began in early October 2025. Once completed, the project will restore approximately 43 acres of habitat within a 67-acre footprint, including low and high marsh, scrub shrub wetland, and maritime upland. Efforts also aim to improve water quality, increase biodiversity, and strengthen the overall Jamaica Bay ecosystem.
The following photos depict the degraded habitat and pre-construction conditions of the site. Stay tuned to our blog for more photos from each of the project phases.
We're pleased to announce the release of the "New Jersey Nature-Based Solutions: Planning, Implementation, and Monitoring Reference Guide," a free resource that provides a comprehensive roadmap to incorporating nature-based solutions (NBS) into infrastructure, construction, restoration, and resilience projects across the state.
Created by the Rutgers University New Jersey Climate Change Resource Center with support from The Nature Conservancy in New Jersey, the guide compiles current research, case studies, best practices, practical tools, science-based strategies, and funding resources to "inform and empower readers to implement and seek funding for NBS."
Click here to view and download the guide now.
As the guide states, "nature-based solutions (NBS) are defined as actions to protect, sustainably manage, and restore natural and modified ecosystems that address societal challenges effectively and adaptively, simultaneously benefiting people and nature." (IUCN 2024)
Whether you're a municipal planner, community leader, contractor, public- or private-sector professional, or an academic, new to NBS or experienced in large-scale restoration projects, the guide offers value at every level with practical instruction that spans the full project lifecycle, from planning and permitting to funding and long-term monitoring. While the content is tailored to New Jersey's diverse landscapes, the guide's insights and approaches are broadly applicable to regions with similar ecosystems, from Massachusetts to Virginia.
The guide also includes insights on how to address equity considerations and foster meaningful community engagement, helping users implement NBS that are both impactful and inclusive.
Princeton Hydro was proud to contribute technical expertise to this important effort. Our Director of Restoration & Resilience, Christiana L. Pollack, CERP, CFM, GISP, participated on the guide's steering committee, and our team provided informational resources, including content and case studies on invasive species management, wetland and floodplain enhancement, and dam and culvert removal to restore rivers and improve fish passage. These contributions along with those from many other participants, reflect the collaborative nature of the guide and the collective commitment to advancing NBS across the state.
The guide's easy-to-follow format includes four key sections:
Whether you're just beginning to conceptualize a project or deep into project implementation, this guide is an invaluable addition to your toolbox. We encourage you to explore, download, and share it widely! Click here to access the guide now.
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