We’re committed to improving our ecosystems, quality of life, and communities for the better.
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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. [gallery link="none" size="medium" ids="9215,19122,9225"] What Is Biochar and Why Use It in Waterbodies? 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. [gallery link="none" columns="2" size="medium" ids="19134,9226"] Aquatic Ecologist Katie Walston-Frederick (right) leads a biochar sleeve filling session. Katie and her team members wear full protective equipment when handling biochar due to the fine, carbon-based nature of the material. Lessons Learned from Five Years of Field Applications 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. Beyond Adsorption: The Role of Biology 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:
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.
Duke Farms, a Center of the Doris Duke Foundation, is a 2,700-acre landscape in Hillsborough, NJ, dedicated to restoring ecosystems, demonstrating sustainable land management, and inspiring environmental leadership. Once the privately-owned estate of J.B. and Doris Duke, the property now welcomes more than 150,000 visitors annually who come to experience its diverse habitats, miles of public trails, and innovative conservation programs.
Situated within the Raritan River Watershed and bordered by a mosaic of rural and suburban development, Duke Farms functions as a living laboratory for nature-based solutions in complex, fragmented landscapes. Its forests, meadows, waterways, and working lands offer an unparalleled setting to advance climate-positive strategies, including restorative land management and decarbonization initiatives, while maintaining an unwavering commitment to protecting wildlife and enriching biodiversity.
For more than 20 years, Princeton Hydro has partnered with Duke Farms to restore, monitor, and manage its interconnected lakes and ponds. In 2001, we developed a comprehensive Lake Management Plan to address water quality challenges, promote ecological balance, and ensure these systems could support both wildlife and public use. Since then, we have provided ongoing updates to align management strategies with the ecological objectives of the Duke Farms Foundation. Over time, the Foundation has expanded public access for education and recreation, highlighting the distinctions between shallow, artificial impoundments and natural lakes while implementing innovative, nature-based techniques for algae and aquatic plant control. Today, Duke Farms’ 11 lakes and ponds, eight of which were included in the original plan, remain central to the property’s water resources and continue to play a vital role in overall ecological health, stewardship programming, and public recreation opportunities.
Great Falls Cove at Duke Farms. Photo by Princeton Hydro Aquatic Ecologist Katie Walston-Frederick.
The original Lake Management Plan integrated routine water quality monitoring, hydrologic and pollutant-load modeling, adaptive aquatic plant management, and targeted interventions to restore ecological balance. Key components included invasive species control, such as Common Carp removal to support native fish populations, and a comprehensive algae and aquatic plant program that included aeration and aquascaping. This multifaceted approach established the foundation for long-term recovery across the lake system.
As Duke Farms expanded public access and strengthened its educational mission, management strategies evolved to emphasize innovative, low-impact techniques for shallow, human-made impoundments. Recent advancements implemented by Princeton Hydro include:
The most recent plan update incorporates techniques that were unavailable when the original plan was developed:
In 2012, Princeton Hydro conducted a detailed hydrologic analysis of Duke Farms’ interconnected lake system to evaluate water management strategies. Historically, water from the Raritan River was pumped into the lakes to maintain water levels. While reliable, this practice introduced elevated nutrients and sediments in the property’s lakes and ponds, degrading water quality and fueling nuisance algal blooms.
The study synthesized pump and discharge records, long-term climate and hydrologic data, and monthly water budgets, and included experimental pumping scenarios to assess alternatives. Results were transformative: under normal conditions, supplemental pumping could be reduced by more than 95%, and even during drought, by about 70%, without compromising lake levels. Based on these findings, Duke Farms adopted a low-volume, seasonal pumping strategy and transitioned to a higher-quality groundwater source, which significantly reduced nutrient loading, improved water clarity, and lowered energy consumption.
Ongoing monitoring remains a cornerstone of the Duke Farms–Princeton Hydro partnership. For each waterbody, the team conducts in-situ data collection, laboratory analyses, visual and observational evaluations, and detailed reporting. Data from continuous monitoring demonstrates sustained improvements in dissolved oxygen, water quality, and overall lake/pond health. This continuous feedback loop informs adaptive management decisions and allows Duke Farms to measure the ecological success of its restoration efforts.
We are proud to partner with Duke Farms in advancing the health and resilience of its water resources, a commitment that not only protects the lakes and ponds on the property but also delivers positive ecological benefits throughout the Raritan River watershed. Click here to learn more about our lake management work in the region. To explore Duke Farms, plan a visit to its beautiful property, sign up for educational programs, or discover ways to get involved in its conservation initiatives, visit Duke Farms’ website.
Welcome to the latest edition of our Client Spotlight blog series, which provides an inside look at our collaboration, teamwork, and accomplishments with one of our client partners.
In this special edition, we’re shining the spotlight on the Town of Mina and Findley Lake Watershed Foundation (FLWF), two organizations working closely together to protect and preserve Findley Lake in Chautauqua County, New York. This charming 300-acre lake is a cherished focal point for recreation, tourism, and community pride, and safeguarding it is a shared responsibility. The Town of Mina and FLWF, a volunteer-led nonprofit, have built a strong partnership dedicated to maintaining the lake’s health and ensuring its long-term sustainability.
We kicked-off the conversation with a question for Rebecca:
Rebecca continues: “As part of our 2024 Comprehensive Plan, the Town of Mina identified four core community values that guide our decision-making, with our top priority being Findley Lake!
The lake is the heart of our community. Ensuring it remains clean, beautiful, and accessible for recreation and overall enjoyment is essential to our identity. That’s why we work so closely with FLWF. During the comprehensive planning process, FLWF developed a Lake Management Plan, which now guides our environmental efforts.
Our second core value is economic development. Findley Lake is experiencing an exciting period of growth, with several initiatives underway, including a new warehouse distribution center, growing retail presence, and revitalization in the downtown area. It’s truly a renaissance moment for our community.
Third, we’re deeply committed to preserving and enhancing our community character. We value our rural lifestyle and are working to improve it with expanded trails, new boardwalks, and safer, more accessible green spaces for all to enjoy. And, our fourth core value centers on strengthening local government, becoming more efficient, effective, and responsive to the needs of our residents. We want people to feel heard, supported, and engaged in the future of our town.”
“FLWF was established in 2002, but our roots go back much further. Before that, our work was carried out by the Findley Lake Property Owners Association, which formed in the late 1940s after the lake was no longer needed as a power source for milling operations.
At that time, the lake and dam were donated by Larry Schwartz to a group of local, stewardship-minded residents. That group did the best they could with limited resources and knowledge. But as science, lake management practices, and environmental awareness progressed, so did our approach.
By transitioning to a 501(c)(3) nonprofit in 2002, we were able to access grant funding and expand our work significantly. Since then, we’ve purchased weed harvesters, partnered with Princeton Hydro for lake studies, and supported major infrastructure projects like the new sewer system currently in development to address septic-related pollution.
We’ve also taken steps to reduce streambank erosion and manage phosphorus loading that affects lake oxygen levels. Our board is strong and diverse—we have dedicated members with the expertise needed to keep moving the organization and the lake forward. At our core, FLWF is committed to maintaining, enhancing, and improving the quality of Findley Lake and its watershed through science-based action and collaboration.”
Rebecca continues: “We’ve made significant strides in advancing the health of our local environment, thanks in part to support from the New York State Department of Environmental Conservation (DEC). We’ve completed three DEC-funded studies that are guiding our next steps.
One study focused on culverts throughout the watershed with the goal of improving water flow and reducing flood risk. Every culvert was assessed to identify those that need repair or replacement. Another study analyzed stormwater runoff, identifying ten key inflow areas to Findley Lake where erosion and sedimentation pose potential threats. Each site was evaluated and prioritized, and we’ve since secured a DEC grant to address the highest-priority site. And, the third study explored in-lake nutrient control strategies, which laid the groundwork for our current partnership with Princeton Hydro on nutrient management efforts.
Beyond lake-focused work, we’re also committed to enhancing community access to nature. We’ve received support from Chautauqua County for efforts that will benefit both the environment and quality of life for residents and visitors alike.”
“We first partnered with Princeton Hydro a few years ago when our board recognized the need for expert guidance on lake management. While we have a strong, professional board, we lacked the specialized knowledge in lake ecology and water quality science to move forward confidently with major decisions.
After researching several firms, we chose to bring Princeton Hydro on board to help us better understand nutrient dynamics in the lake. One of our key concerns was the persistent late-summer algae blooms, which we later learned were linked to phosphorus being released from the lake’s sediments.
Princeton Hydro conducted an in-lake nutrient study that clearly explained this internal loading process and helped us chart a path forward. Building on that work, we’re now working with the Princeton Hydro team on a bathymetric and sediment analysis to guide our next step, which will be to install an aeration system to reduce phosphorus release and improve water quality.
Princeton Hydro’s expertise has been instrumental in making complex science understandable and actionable, which has helped us take meaningful steps toward restoring the health of Findley Lake.”
Following Rebecca’s remarks, Ed adds: “I’d just like to echo what Rebecca said—the Princeton Hydro team we worked with this Spring was truly a pleasure to collaborate with. Their depth of knowledge was impressive, but just as important was their ability to communicate complex concepts in a way that was clear and easy for our board to understand. That kind of approachability made a big difference. It was a great experience working with them.”
“We’re always grateful for donations, they fuel much of what we do. But beyond financial support, one of the most valuable ways people can contribute is by sharing their experiences and ideas.
There are countless lakes and watershed organizations out there facing similar challenges, and many have come up with innovative, cost-effective solutions. We’re always eager to learn from others; whether it's a new technology, a successful restoration approach, or a creative funding strategy. Collaboration and information-sharing are incredibly powerful tools in watershed management. If you’ve worked on a similar issue or simply have ideas that could help, we’d love to hear from you. The more we connect and learn from each other, the better we can protect and improve Findley Lake for generations to come.”
Following Ed’s comments, Rebecca adds: “One of the things that makes the Town of Mina so special is the strong culture of volunteerism. We’re fortunate to have many residents, often individuals who’ve had professional careers elsewhere, who bring their skills, energy, and passion to our community.
Even though we’re a small town, we benefit from a wide network of nonprofit organizations and local initiatives. For example, the Findley Lake Nature Center is actively working on trail development, and there are many other opportunities for people to get involved in stewardship, whether it’s helping maintain green spaces, supporting water quality efforts, or sharing expertise on local projects.
What’s especially unique about our community is how welcoming we are. Newcomers don’t have to wait decades to feel at home here—they’re embraced right away, and their ideas are valued. That openness has really enhanced our ability to protect Findley Lake and strengthen the town as a whole.”
In the video below, Ed reflects on the strong sense of community in the Town of Mina and the local support that fuels the ongoing efforts to protect and preserve Findley Lake:
After Ed’s remarks, Rebecca shares a few additional reflections: “One particularly meaningful designation we’ve received is from New York State, which has identified us as one of only two rural NORCs (Naturally Occurring Retirement Communities) out of 43 statewide. This designation recognizes our vibrant population of older adults and has allowed us to pursue new forms of support and services. We’re currently looking into developing a pocket neighborhood to help seniors remain in the community, where they continue to be active, involved, and deeply valued.
And here’s a fun fact that speaks to the energy of Findley Lake: it serves as the practice site for the women’s rowing team from Mercyhurst University, who happen to be the reigning national champions. Pretty cool, right?”
Yes, Rebecca, we think that’s very cool!
A heartfelt thank you to Rebecca and Ed for their partnership and for taking the time to speak with us to share their passion for protecting Findley Lake and strengthening the Town of Mina. Their leadership and collaboration exemplify the power of community-driven stewardship.
To learn more about their work and how you can get involved, we encourage you to visit the Town of Mina’s website and FLWF at findleylakewf.org.
Click here to read the previous edition of our Client Spotlight Series featuring Farmington River Watershed Association Executive Director Aimee Petras.
Ever wondered how scientists measure lake water clarity? One of the simplest and most enduring tools for the job is the Secchi disk.
Long before it became a formal scientific tool, sailors and scientists were already using simple methods to estimate water clarity, like lowering white objects into the water to gauge visibility and depth. In 1865, Italian astronomer Father Pietro Angelo Secchi built on these early techniques by developing a uniform white disk and standardized utilization method. His published findings helped establish the Secchi disk as a practical tool for water quality assessment.
The design was later improved by George C. Whipple, who added alternating black and white quadrants to enhance visibility. Today, this version of the Secchi disk remains a staple in the field kits of aquatic scientists and limnologists worldwide.
As part of our Field Notes blog series, which spotlights essential tools and techniques used by our team, Senior Aquatics Manager Christopher L. Mikolajczyk, CLM, demonstrates how to properly use a Secchi disk and explains how this simple method helps inform lake and pond management strategies. Watch now:
As Chris explains in the video, water clarity is a key indicator of overall lake health, and monitoring it provides valuable insight into the condition and functioning of aquatic ecosystems. Regular monitoring helps lake managers understand whether conditions are within a healthy range, identify potential indicators of future algal blooms, and make informed decisions to maintain ecological balance.
Interested in getting involved? With a few simple materials, you can build your own Secchi disk and participate in the Secchi Dip-In, a community science initiative where volunteers measure and report water clarity data. While the Dip-In is traditionally celebrated in July during Lakes Appreciation Month, data collection is welcomed and encouraged year-round.
Chris has dedicated over 25 years to advancing the science and practice of aquatic ecology and water resource management. His expertise spans the management, oversight, and coordination of projects in three key areas: aquatic resource restoration and management, aquatic ecosystem sampling and investigations, and stormwater quality modeling and management. Chris has an Associate's, Bachelor's, and Master's degree in Water and Watershed Resource Management. In addition to his work with Princeton Hydro, Chris currently serves as the President-Elect of the Colorado Lake and Reservoir Management Association’s 2025 Board of Directors and has also served as President of North American Lake Management Society. These leadership roles highlight his dedication to advancing aquatic resource conservation.
Invasive species can quickly establish themselves in habitats ranging from freshwater wetlands and riparian corridors to stormwater basins and tidal marshes, disrupting ecological balance and biodiversity, altering hydrology, and displacing native species.
Addressing these impacts requires a thoughtful, site-specific approach. Our team at Princeton Hydro works to design and implement targeted strategies that promote long-term ecological function. These integrated efforts aid in native habitat recovery, enhance water quality, and support compliance with regulatory frameworks.
Let’s take a closer look at how invasive species disrupt our ecosystems, why managing them is so important, and the cutting-edge tools and innovative techniques helping to eradicate invasives and restore balance to delicate ecosystems.
Invasive species are organisms introduced outside their native range that proliferate in new environments, often to the detriment of local ecosystems and biodiversity. Although some introductions happen naturally, most are caused by human activity—through commercial shipping and transport, travel and outdoor recreation, or sometimes deliberate introduction. Once established, invasive species often outcompete native species by growing more aggressively, reproducing more rapidly, and exploiting resources more efficiently. These advantages are amplified by the absence of natural predators and environmental controls that would normally regulate their populations.
This can lead to a cascade of ecological consequences:
Take common reed (Phragmites australis), for example. This fast-growing plant has overtaken many wetlands, meadows, and shorelines, forming dense stands that outcompete native vegetation. These monocultures reduce food sources that native species rely on and block the movement of wildlife between critical habitats. According to the National Invasive Species Information Center (NISIC), Phragmites was most likely introduced during the 1800s in ballast material used on ships. It was initially established along the Atlantic coast and quickly spread across the continent.
Another example of an aggressive invasive species is Eurasian watermilfoil (Myriophyllum spicatum), a submerged perennial aquatic plant that grows in lakes and ponds. Native to Europe, Asia, and North Africa, it was discovered in the eastern U.S. in the early 1900s, likely introduced and spread through the movement of watercraft. It establishes itself very quickly, grows rapidly, and spreads easily, forming dense mats at the water’s surface.
Left unmanaged, aggressive invasives like Phragmites and Eurasian watermilfoil can severely impact the stability of critical environmental systems. Effective control strategies help restore balance, preserve biodiversity, and safeguard the services ecosystems provide to humans and wildlife alike.
At Princeton Hydro, we use a multifaceted approach to invasive species control, employing mechanical, herbicidal, and biological strategies depending on the specific site conditions and project goals. One of our most effective tools is the Marsh Master® 2MX-KC-FH, a fully amphibious machine built to operate with minimal environmental disruption.
Equipped with hydraulic rotary cutting blades, a rear mounted roller/chopper attachment, and a front vegetation plow, the Marsh Master® cuts through dense vegetation like Phragmites, then chops and rolls the stalks, effectively preparing the soil for native seed germination or plug installation, making it ideal for nature preserves, canal banks, and restoration sites. Its light footprint (less than one pound per square inch) means it can traverse sensitive areas without damaging the soil or root layer.
Take a look at the Marsh Master® in the field, tackling Phragmites in tough terrain:
When paired with herbicide treatments and long-term monitoring, this approach has proven very effective in eradicating invasives, restoring wetland biodiversity, improving water quality, and creating wildlife habitat. Each site is carefully analyzed and, when required for optimal non-native plant management, a site-specific USEPA and state-registered herbicide is chosen to control the target plants while preserving the desirable, native vegetation currently populating the site. Application techniques, which are also specific to each site, include machine broadcast spraying, backpack foliar spraying, hand-wiping, basal applications, herbicide injection lances, along with various other techniques.
In partnership with GreenVest and the U.S. Army Corps of Engineers Baltimore District, Princeton Hydro contributed to a tidal marsh restoration project along the Patapsco River in Baltimore, Maryland. This initiative is part of the broader “Reimagine Middle Branch” plan, a community-driven revitalization effort to restore natural habitat and improve public access along 11 miles of Patapsco River shoreline.
At the project site near Reed Bird Island, roughly five acres of marsh had been overtaken by dense stands of Phragmites. The goal was to restore hydrologic connections to the Patapsco River and convert the monoculture into a thriving mosaic of native marsh vegetation. Our team used the Marsh Master® to mow and manage the Phragmites, followed by mechanical grading and sediment redistribution to create high and low marsh zones. The restoration plan included planting 5+ acres with a combination of native species and incorporating habitat features like woody debris and unplanted cobblestone patches to facilitate fish passage.
This project demonstrates how targeted invasive species control can support large-scale ecosystem restoration, community-led initiatives, and watershed-wide environmental goals.
Princeton Hydro has worked alongside New Jersey’s Mercer County Park Commission for over a decade to restore and protect some of the region’s most ecologically valuable landscapes. From comprehensive planning to boots-on-the-ground restoration, our efforts have focused on mitigating the spread of invasive species and promoting long-term ecological resilience.
John A. Roebling Memorial Park, part of the Abbott Marshlands, an ecologically rich freshwater tidal ecosystem that contains valuable habitat for many rare species, experienced a significant amount of loss and degradation, partially due to the introduction of Phragmites. In areas where Phragmites had overtaken native wetland communities, our team developed and executed an invasive species management plan tailored to the park’s unique hydrology and habitat types. Seasonal mowing in the winter and early spring with the Marsh Master® and targeted herbicide applications helped suppress invasive growth and enabled the rebound of native species, including Wild rice (Zizania aquatica), a culturally and ecologically significant plant.
Building on that success, we contributed to the development and implementation of the Master Plan for the Miry Run Dam Site 21, a comprehensive roadmap for ecological restoration and public access. We are advancing that vision through mitigating invasive species (primarily Phragmites), leading lake dredging, and executing a variety of habitat uplift efforts. Click here to learn more about this award-winning restoration initiative.
In 2024, Mercer County retained Princeton Hydro under an on-call contract for invasive species management across its park system, enabling our team to respond rapidly to emerging threats and support the county’s ongoing commitment to long-term ecosystem health.
At the Lower Raritan Mitigation Site in central New Jersey, Princeton Hydro has led a multi-year invasive species control effort as part of a larger wetland and stream restoration initiative. Dominated by reed canary grass (Phalaris arundinacea) and Phragmites, the site had lost most (if not all) of its native biodiversity and ecological function.
Our team used a phased approach—mechanical mowing, herbicide treatment, and active planting of native species—to gradually suppress invasives and restore a healthy plant community. Monitoring data over several growing seasons has shown a significant decrease in invasive cover and a measurable increase in native diversity. Ongoing eradication of aggressive species and the promotion of native plant diversity are steadily guiding the site toward a resilient, self-sustaining ecosystem.
Owned and managed by The Nature Conservancy in New Jersey, the South Cape May Meadows Preserve is a 200-acre freshwater wetland and coastal habitat in southern New Jersey that serves as a critical refuge for migratory birds and other native wildlife. The preserve attracts over 90,000 visitors each year and is internationally recognized as a prime birdwatching destination.
Princeton Hydro is collaborating with The Nature Conservancy on a multi-faceted effort to both improve public access and restore the site’s ecological integrity. In 2023 and 2024, our team initiated the mechanical removal of dense stands of Phragmites using the Marsh Master® to suppress monocultures and promote native plant regeneration. Future phases may include targeted herbicide treatments and additional mechanical work.
In addition to the invasive species management component, this project collaboration has led to the construction of 2,675 feet of new elevated boardwalks, a 480-square-foot viewing platform, and enhancements to existing trails. Designing and installing these features across sensitive wetland terrain required a thoughtful, low-impact approach. The result is a more welcoming, species-rich, and resilient landscape that invites people into nature while actively protecting it.
Invasive vegetation doesn’t just affect wild landscapes, it also poses challenges for stormwater infrastructure. Many municipalities struggle with invasives overtaking stormwater basins, reducing their capacity and function, which can lead to violations of Municipal Separate Storm Sewer System (MS4) permits and municipality stormwater management regulatory requirements.
Princeton Hydro designs and implements comprehensive stormwater basin maintenance programs that include invasive species management. Removing Phragmites, broadleaf cattail (Typha latifolia), and other aggressive species from stormwater infrastructure helps to restore hydrologic flow and ensures the basins perform as designed. These maintenance programs also help maintain MS4 compliance, protect downstream water quality, and reduce flooding risks—while enhancing habitat value where possible.
The fight against invasive and aggressive non-native species is ongoing, and success requires a combination of science, strategy, and stewardship. Each effort implemented and every acre reclaimed is a step toward protecting the ecosystems we all depend on.
Nestled in Luzerne County, Pennsylvania, Harveys Lake spans 622 acres and is the largest natural lake by volume in the Commonwealth. Beyond its scenic beauty and popularity as a recreational destination, the lake plays a critical ecological role in the region.
Harveys Lake forms the headwaters of Harveys Creek, which flows into the Susquehanna River and ultimately the Chesapeake Bay. As such, it is part of the greater Susquehanna River Valley and contributes to the health of the Chesapeake Bay watershed. The lake and its outflow are designated High Quality – Cold-Water Fisheries, supporting sensitive aquatic life, providing vital cold-water habitat, and contributing to regional biodiversity.
Given its ecological significance and its connection to regional waterways, efforts to manage stormwater and reduce nutrient pollution in the Harveys Lake watershed are more than just local improvements, they are integral to protecting downstream water quality all the way to the Chesapeake Bay.
In 2022, building on decades of water quality initiatives, the Borough of Harveys Lake launched a forward-thinking pilot project to enhance stormwater treatment using innovative nutrient-filtering technologies. Supported by funding from the National Fish and Wildlife Foundation (NFWF) Chesapeake Bay Small Watershed Grant Program and designed and implemented in partnership with Princeton Hydro, this project explores the use of biochar and EutroSORB® filtration media to capture dissolved nutrients, an important step toward improving water quality and meeting regulatory goals.
This blog explores the local history of water management at Harveys Lake, the science behind this novel pilot approach, and the broader implications for watershed protection across the region.
Once a remote, wooded landscape, the Harveys Lake area was settled in the early 19th century and gradually developed into a hub for timbering and milling. By the late 1800s, the lake was regularly stocked with game fish, and with the arrival of the railroad in 1887, it quickly became a popular summer destination. The shoreline soon featured hotels, restaurants, and even an amusement park.
As the community flourished, the lake's natural systems began to show signs of strain. Like many waterbodies across the country, Harveys Lake faced growing water quality challenges driven by stormwater runoff, nutrient pollution, and a lack of formal environmental protections. By the 1960s, declining water clarity and seasonal algal blooms began to impact recreation, contributing to the lake’s gradual transition from a bustling public getaway to a primarily residential community.
A significant shift occurred following the passage of the U.S. Environmental Protection Agency’s Clean Water Act of 1972. Harveys Lake established a municipal sewer authority, and construction began on a utility line around the lake's perimeter to reduce point-source pollution. Still, algae blooms persisted throughout the 1980s, fueled by nonpoint sources such as stormwater runoff, lawn fertilizers, and waterfowl droppings.
In 1994, a Phase I Diagnostic Feasibility Study was conducted that formally identified Harveys Lake as impaired due to recurring algal blooms linked to elevated nutrient levels. Following this study, a Total Maximum Daily Load (TMDL) was established, and management efforts were initiated to meet long-term water quality goals.
Since 2003, the Harveys Lake watershed has undergone extensive stormwater management efforts, including the installation of numerous manufactured treatment devices (MTDs) to reduce pollutant loading. Most of these MTDs are nutrient separating baffle boxes (NSBBs), chosen due to the watershed’s steep slopes, dense residential development, and shallow bedrock. The first NSBB, pictured below, was installed at Hemlock Gardens:
In 2009, the Borough of Harvey’s Lake worked with Princeton Hydro to develop a Stormwater Implementation Plan that laid the foundation for future restoration efforts. Over the following years, the Borough of Harveys Lake, supported by state and regional grants, implemented 34 stormwater best management practices (BMPs) and installed four floating wetland islands throughout the watershed.
These projects were strategically designed to reduce nutrient loading, enhance water quality, and move the lake closer to achieving its TMDL targets. Click here to read more about these efforts.
While NSBB stormwater BMPs are highly effective at capturing sediments and associated pollutants, they are limited in their ability to remove dissolved nutrients, particularly nitrogen and phosphorus. This is evident in the Harveys Lake Watershed, where NSBBs remove approximately 70% of total suspended solids (such as sediment and plant debris), 35% of total phosphorus, and 0% of total nitrogen. To address this gap and improve overall nutrient removal efficiency, the Borough of Harveys Lake received funding from the NFWF Chesapeake Bay Small Watershed Grant Program to augment existing MTD stormwater BMPs using new filter technologies.
Partnered with Princeton Hydro for design, implementation, and technical support, the Borough launched a unique pilot project involving the installation of biochar and EutroSORB® (manufactured by SePRO Corporation) to evaluate the effectiveness of these two innovative materials in removing dissolved phosphorus and total nitrogen from stormwater runoff before it reaches Harveys Lake.
Biochar, a carbon-rich material derived from plant biomass, is valued for its high surface area and nutrient-adsorption capacity. EutroSORB® is a manufactured media specifically engineered to bind and retain dissolved phosphorus with demonstrated effectiveness in aquatic systems.
Filter socks filled with either biochar or EutroSORB® were installed at key stormwater outfalls and stream inlets that drain directly to the lake. At four NSBB sites, the socks were secured beneath manhole covers using a rope-and-carabiner system designed for easy, seasonal replacement. Each sock weighs approximately 50–60 pounds when saturated and was carefully positioned to avoid dislodgement or blockage of outlet pipes during high-flow events.
At the Hemlock Gardens site, which features a larger, multi-tray baffle box, twelve filter socks were installed across two horizontal trays to maximize contact time between stormwater and the filter media.
By integrating these innovative filter techniques into the existing BMP infrastructure, the Borough of Harveys Lake is taking a proactive, science-based approach to nutrient reduction and long-term water quality improvement.
Princeton Hydro implemented a comprehensive water quality monitoring program in the Harveys Lake watershed to assess the real-world performance of the biochar and EutroSORB® filtration systems under varying hydrologic conditions, with a particular focus on dissolved nutrients that contribute to eutrophication.
Six stormwater monitoring stations were established at locations where biochar or EutroSORB® were deployed within NSBBs or stream inlets. Each site included paired upstream (pre-treatment) and downstream (post-treatment) sampling points to capture the nutrient concentrations entering and exiting the filtration media.
Stormwater sampling was conducted during six separate rainfall events between March and April 2025. At each location, during storm flow conditions, discrete grab samples were collected via a portable polyethylene sampling pole and analyzed for key water quality parameters.
Beyond concentration-based comparisons, Princeton Hydro used empirical monitoring data to model pollutant loads upgradient and downgradient of the filtration media. These load estimates provide insights into pollutant removal effectiveness on a mass basis, with a focus on:
Emphasis was placed on SRP—the biologically available form of phosphorus most readily assimilated by algae and a key driver of harmful algal blooms and eutrophication. Because phosphorus is the target pollutant in Harveys Lake’s TMDL, SRP reduction serves as a critical indicator of the filtration media’s performance and its potential role in long-term water quality management strategies.
Overall, the study revealed variable but promising results across media types and installation locations:
These early findings suggest that both EutroSORB® and biochar hold promise as cost-effective tools for reducing soluble phosphorus in stormwater runoff. Additionally, observed differences in removal efficiency, based on installation context (NSBB vs. stream), filter media volume, and site-specific hydrologic conditions, underscore the importance of continued monitoring and system refinement.
As part of the project’s commitment to long-term sustainability and public education, a native pollinator garden was established near the Harveys Lake Department of Public Works garage, adjacent to the Little League fields.
After the final sampling in April 2025, the nutrient-saturated biochar and EutroSORB® socks were removed from the stormwater treatment systems. The spent biochar, having captured phosphorus and nitrogen from runoff, was repurposed as a soil amendment to enrich a 500-square-foot planting area. 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.
The Harveys Lake Environmental Advisory Council volunteered to help plant the garden, installing 450 native plant plugs across nine species including Foxglove Beardtongue, Clustered Mountain Mint, Blue Wild Indigo, and Common Yarrow to attract pollinators such as butterflies, bees, and songbirds.
Designed by Princeton Hydro, the pollinator garden serves as both an ecological asset and an educational tool. Its prominent location next to the ballfields encourages community engagement, and an interpretive sign on-site helps visitors understand the garden’s purpose and its connection to local water quality initiatives. The sign features a QR code linking to an interactive ArcGIS StoryMap, developed by Princeton Hydro, which explores the broader context of the project. It draws connections between nutrient management efforts in Harveys Lake and similar challenges facing the entire Chesapeake Bay watershed, emphasizing how local actions contribute to regional water quality improvements. To support public outreach, the StoryMap was also shared on the Borough’s website, making this educational resource widely accessible to the community.
It is important to note that while this project illustrates a successful example of biochar reuse, all reuse applications must be assessed on a case-by-case basis. For example, biochar exposed to hazardous pollutants is not suitable for soil use. In this case, the biochar had only been used to absorb excess nutrients, making it appropriate for the garden setting.
Supported by the U.S. Environmental Protection Agency and the NFWF’s Chesapeake Bay Stewardship Fund, which promotes community-based conservation strategies to protect and restore Chesapeake Bay’s natural resources, this project was designed with scalability in mind. A core objective was to evaluate whether these filtration media could be more broadly implemented throughout the Chesapeake Bay watershed as a low-cost, community-integrated strategy for achieving water quality goals.
Through continued innovation and shared learning, small-scale efforts like this can drive large-scale impact, proving that effective water quality solutions don’t have to be costly or complex. The Harveys Lake model offers a replicable framework that communities across the region can adopt and adapt, empowering local action that contributes meaningfully to the restoration and resilience of Chesapeake Bay.
The Borough of Harveys Lake, in partnership with Princeton Hydro, launched a new interactive ArcGIS StoryMap that chronicles the community’s long-standing commitment to water quality and showcases a recently completed pilot project aimed at reducing stormwater nutrient pollution.
This engaging digital resource combines maps, multimedia, charts, diagrams, and narrative storytelling to bring the science and history of Harveys Lake’s multi-year environmental restoration efforts to life. It explores both the local impact and the broader significance of these initiatives, drawing connections to similar water quality challenges throughout the Chesapeake Bay Watershed.
Designed with accessibility in mind, the StoryMap invites users to explore project sites, restoration progress, and technical details without the need for specialized GIS training or software. Interactive features, such as zoomable maps, clickable pins, and site-specific details, offer an intuitive, user-friendly experience.
More than just a visualization tool, the StoryMap serves as a community-education and engagement platform. It highlights how local stormwater management strategies, like those implemented at Harveys Lake, can drive positive, region-wide change, underscoring the vital role of place-based solutions in improving watershed health across the Chesapeake Bay region.
The StoryMap begins with an exploration of the Chesapeake Bay Watershed—one of the most ecologically and economically significant estuaries in the United States. This region faces complex environmental challenges, including nutrient pollution, habitat loss, and climate change impacts. Over the past several decades, a wide range of stakeholders have engaged in coordinated restoration efforts to protect and improve water quality across the watershed.
Using interactive maps, expandable sections, and rich visuals, this introductory portion of the StoryMap places Harveys Lake in a broader regional context. It sets the stage for understanding how local action, such as nutrient reduction at Harveys Lake, plays a critical role in supporting the health of the entire Chesapeake Bay ecosystem.
The next section, “Harveys Lake: A Case Study,” highlights the Borough's ongoing dedication to protecting the lake and improving water quality through science-based solutions and collaborative efforts. The StoryMap provides:
The final section of the StoryMap dives into a 2025 pilot initiative that used biochar and EutroSORB® filter media to reduce dissolved phosphorus and total nitrogen from stormwater runoff. Organized into subsections—Project Information, Methodology, Results and Discussion, Pollinator Garden, and Future Implications—the StoryMap offers a detailed look at this innovative nutrient-reduction strategy and its potential for replication across the Chesapeake Bay watershed.
In addition to detailing the pilot project, this section also spotlights the creation of a native pollinator garden, planted using the spent biochar as fertilizer. This closed-loop approach not only reinforces the project’s long-term ecological value but also demonstrates how thoughtful design can deliver multiple environmental benefits while cultivating a vibrant community-oriented space that supports local biodiversity.
To extend the impact of this initiative, the StoryMap was provided to the Harveys Lake Borough Environmental Advisory Council (EAC) and is publicly accessible via the Borough’s website. A QR code linking to the StoryMap is also featured on the new pollinator garden sign at the project site, allowing visitors to engage with the digital experience in real time.
By blending maps, visuals, and interactive storytelling, this StoryMap serves as both an educational tool and a digital archive of the latest Harveys Lake water quality project and its long history of stewardship. We invite you to explore this engaging platform and see firsthand how thoughtful, science-based restoration is shaping a healthier future for Harveys Lake, and the entire Chesapeake Bay watershed.
This material is based on work supported by the U.S. Environmental Protection Agency (Assistance Agreement No. CB96358101) and the National Fish and Wildlife Foundation’s Chesapeake Bay Stewardship Fund, which supports community-based strategies to conserve and restore the Chesapeake Bay’s natural resources. Click here to learn more information about the grant program.
Click here to learn more about Harveys Lake or how to get involved in a Harveys Lake Borough Environmental Advisory Council stewardship program.
Lake Hopatcong, New Jersey's largest freshwater lake, spans 2,600 acres and stretches over six miles, forming part of the border between Sussex and Morris counties in the state’s northern Highlands region. Just 40 miles from Manhattan, its proximity to the city, combined with its scenic beauty, recreational appeal, and rich biodiversity, has long made it a desirable destination for visitors, residents, and businesses alike. The lake’s waters and surrounding habitats support diverse wildlife, including aquatic plants, animals, birds, and other terrestrial species.
Increased residential and commercial development, along with the impacts of climate change, have placed growing pressures on the lake’s ecosystem. Managing these pressures is vital to preserving water quality and protecting the biodiversity of both the lake and its watershed.
The Lake Hopatcong Foundation (LHF) and Lake Hopatcong Commission (LHC) are dedicated to protecting the lake and balancing development with environmental stewardship. Through thoughtful planning, long-term sustainability initiatives, and strategic partnerships, they have worked to safeguard the lake’s ecological, economic, and recreational value.
Princeton Hydro, a long-standing partner in this effort, has been involved in restoring the lake and managing its watershed for over 30 years. Our work has focused on reducing pollutant loads, managing stormwater runoff, addressing invasive aquatic plants and nuisance algal blooms, and enhancing habitat quality. Together with LHF, LHC, and funding partners, we have implemented a variety of projects designed to protect the lake and the communities that rely on it.
As a key partner, the New Jersey Highlands Council (Highlands Council) has provided essential funding for many of these critical projects, ensuring they come to fruition. These efforts reflect the Council’s commitment to safeguarding Lake Hopatcong’s future while upholding the Highlands Act’s mission to protect natural resources and foster sustainable community growth. These collaborations are vital to the initiatives that preserve the lake’s water quality, restore habitats, and promote the long-term health of the region.
In celebration of its 20th anniversary, the Highlands Council hosted a special event, which featured a “Lake Hopatcong Exhibit,” highlighting many of the successful projects that it funded. Representatives from LHC, LHF, Highlands Council, and Princeton Hydro, were on hand to discuss the significance of these projects and their contributions to the long-term health of the lake and surrounding communities.
The exhibit included a variety of interactive experiences, including informative posters and maps detailing project efforts. Participants were able to examine Lake Hopatcong water samples under microscopes with guidance from Dr. Fred S. Lubnow, Princeton Hydro Senior Technical Director of Ecological Services.
By highlighting both the challenges faced and the progress made, the exhibit offered attendees a deeper understanding of the lake’s critical role in the region’s environmental and economic sustainability as well as the ongoing efforts to maintain the lake's water quality and protect its ecological health.
Through funding from the Council, a variety of partners including LHF, LHC, Princeton Hydro, and local government agencies have been able to implement a myriad of projects. From stormwater management systems to watershed restoration efforts, these initiatives are designed to address issues like nutrient pollution, invasive species, and habitat degradation. These projects are helping to protect the lake’s water quality and ensure its healthy future:
In 2021, the Upper Musconetcong River Watershed Restoration Plan was updated to a 9-element WIP. This revision re-evaluated existing conditions, integrated green infrastructure, and incorporated emerging technologies. The WIP has since facilitated funding for projects such as biochar installation, alum treatments to reduce phosphorus, and stormwater management improvements. 25% of the WIP ($27,250) was used as match toward a National Fish and Wildlife Foundation (NFWF) grant ($485,650). This effort led to NJDEP 319 (h) Stormwater Grant for Biofiltration at Lakeside Fields ($239,000).
A restoration plan was developed for the watershed that directly flows to Memorial Beach through the park. A series of stormwater management measures were recommended and subsequent funding was secured. This effort led to community-funded project for the dredging of Memorial Pond ($277,000) and a slope stabilization with native plantings at Memorial Pond via a NJ Department of Environmental Protection 319(h) grant. $70,500 was also used as match for NFWF Glen Brook Project (Total Project - Glen, Muscy, Witten - $485,650)
Erosion of Floating Island, which located in Lake Hopatcong’s Landing Channel, contributed to significant sediment accumulation. A preliminary feasibility study conducted by Princeton Hydro explored dredging and habitat restoration options. The proposed beneficial reuse/dredging project would rehabilitate the island and lead to reduced phosphorus in the lake, increased beneficial wetland habitat, and improved water quality. The next phase of the project includes engineering design, permitting, and implementation.
A 25+ year-old feasibility study was updated to lay the groundwork for the the installation of sanitary sewers along the lakefront area of Jefferson Township, which is currently using septic systems. This marked the first step in addressing one of largest sources of phosphorus entering Lake Hopatcong and a pivotal milestone in the ongoing efforts to safeguard water quality and mitigate the risk of harmful algal blooms (HABs) on Lake Hopatcong. These efforts led to a Community Funded Project from Congresswoman Sherill’s Office ($750,000).
A bank stabilization design and planting plan was completed for a popular fishing location along the Musconetcong River between Lakes Hopatcong and Musconetcong. The project, led by the LHC with technical assistance from Princeton Hydro, aims to reduce sediment and nutrient levels in Lake Musconetcong by improving the condition of a key section of the Musconetcong River. The Highlands Council grant to Roxbury Township provided the critical first step in this long-term, multifaceted project.
Princeton Hydro completed a feasibility study for the design of an oxygenation system for Lake Hopatcong. It aimed to address the lake’s internal phosphorus load that contributes toward the nuisance HABs over the summer months. Since the widespread occurrence of HABs in 2019, the LHF and the LHC have been actively exploring solutions to reduce their frequency. Oxygenation systems help prevent stagnation of water, increasing circulation, disrupting thermal stratification which provides “through-column” mixing, and minimizes the occurrence of HABs. The results of this study will be used to move the project forward into the permitting and implementation phases.
A planting plan and regenerative stormwater conveyance system design was completed to aid in the mitigation of stormwater in Witten Park. A new system will help to manage and treat stormwater within the park, reducing erosion and sediment that flows into Lake Hopatcong. The system will also restore the floodplain, wetlands, and streams, and improve the ecological health of the area. The funding from the Council was also used by LHC as in-kind match for a NFWF grant award ($353,000) for the permitting & implementation phases.
One of the most significant recreational draws to Lake Hopatcong is its trout fishery, recognized regionally by anglers and established as an important component of the local economy. Data collected over the past 30 years at the lake was analyzed and showed increasing surface water temperatures, a trend that may suggest that the trout carryover habitat is being negatively impacted. The LHC, in cooperation with the LHF and the Knee-Deep Club, initiated a three-year trout tagging study. The study focused on the introduction of larger trout to assess the long-term population dynamics of those stocked fish and the general health of the fishery.
Planning documents, a hydraulic & hydrologic analysis, and an engineering report were prepared for the construction of two stormwater basin retrofits. The stormwater basin retrofit project aims to minimize runoff and reduce pollutants flowing into Lake Hopatcong, thus protecting water quality. The reconstruction of the basins is critical in managing stormwater effectively, preventing erosion, and reducing nutrient loads that contribute to harmful algal blooms. By improving these basins, the project plays a key role in safeguarding the lake's ecosystem and ensuring the long-term health of its water resources.
A field assessment, survey, and engineering design was completed for the installation of stormwater treatment devices at each of the outfall systems at the Shore Hills Beach Club property, which is located at the southern most tip of Lake Hopatcong. The primary goal of the project is to reduce phosphorus loads entering the lake, which can lead to nuisance weed growth, reduced water quality, and the proliferation of HABs. This funding from the Council enabled the project's next phase: construction.
As we celebrate the 20th anniversary of the New Jersey Highlands Council and its vital contributions to Lake Hopatcong, it’s clear that the future of this treasured resource relies on ongoing collaboration among stakeholders, local communities, and environmental organizations. By implementing innovative solutions and promoting sustainable practices, we can ensure that Lake Hopatcong continues to thrive as both an ecological haven and a recreational hub. This collective effort not only enhances the lake’s water quality and biodiversity but also strengthens the economic vitality of the surrounding communities, fostering a legacy of environmental stewardship for generations to come.
Mercer County Park, spanning over 2,500 acres across the Townships of West Windsor, Hamilton, and Lawrence, is a treasured natural resource. Like many waterbodies throughout New Jersey, some of the lakes within Mercer County Park have been increasingly affected by harmful algal blooms (HABs) in recent years. In response to the growing frequency, duration, and severity of these blooms, the Mercer County Park Commission (MCPC) has intensified its efforts to enhance the overall health of its lakes.
To address these challenges, the County of Mercer tasked the MCPC with developing a comprehensive Lake and Watershed Management Plan. The ultimate goal is to ensure the health, stability, and sustainability of the park's aquatic ecosystems, thereby enhancing the recreational experience for park users. In this endeavor, the MCPC has partnered with Princeton Hydro to bridge gaps in the existing data and create a thorough management plan.
The plan documents the current conditions of waterbodies within the park, including Mercer Lake, which is the largest, and its surrounding watershed; identifies and prioritizes existing and potential water quality challenges; and provides targeted recommendations for treatment and restoration.
Princeton Hydro conducted a detailed analysis of the lakes' ecological health, including water quality monitoring, bathymetric mapping, and assessment of hydrologic and pollutant budgets. These comprehensive efforts have culminated in a robust management plan designed to protect and improve the lakes' ecological balance and recreational value.
While Mercer Lake is a key focus, Princeton Hydro's commitment extends beyond this single waterbody. Recognizing the interconnected nature of the county's aquatic ecosystems, the team conducted similar analysis and developed Lake and Watershed Management Plans for three additional lakes in other parks within Mercer County.
Each of these lakes, like Mercer Lake, faces unique challenges related to maintaining water quality, protecting ecological balance, and mitigating HABs. By applying a comprehensive approach tailored to the specific conditions and needs of each lake, Princeton Hydro aims to enhance the overall health of these vital resources.
Let's dive into the details of Mercer Lake's plan!
The first crucial step in developing Mercer County Park's comprehensive lake management plan involved a thorough review of historical data obtained from various sources, including the County, New Jersey Department of Environmental Protection (NJDEP), New Jersey Department of Transportation (NJDOT), and U.S. Geological Survey (USGS). This review was essential for capitalizing on established water quality trends, identifying recurring problems, and evaluating the success of previous restoration efforts.
The historical data review spanned an impressive range of years from 1963 to 2016, though it did contain some significant gaps. Despite these gaps, the long-term data provided invaluable insights into the lake's ecological history. By integrating reliable data from past studies, the team could complement their field efforts with supplemental information.
Princeton Hydro examined data on Mercer Lake, a key focus of the management plan initiative, and on all streams within each watershed that feed into the lake. This included any available surface water data from the USGS, a standard approach in aquatic system studies. By analyzing these data, the team identified trends in water quality, highlighted persistent issues, and assessed the effectiveness of past restoration efforts.
This comprehensive historical data review set the stage for a robust watershed assessment, ensuring that the management plan would be informed by a solid foundation of past knowledge.
A bathymetric survey is a scientific method used to map the depths and topography of waterbodies, providing detailed information about the underwater terrain and the distribution of sediments. This survey is crucial for understanding various aspects of a lake's ecosystem, including sediment thickness, water volume, and potential areas for dredging. The data gathered from a bathymetric survey helps in making informed decisions regarding the restoration and protection of lakes.
Princeton Hydro conducted the bathymetric survey using a calibrated sounding rod for shallow areas and a dual-frequency echo sounder with GPS for deeper regions. The sounding rod was employed in areas with water depths of 12 inches or less and where sediment composition hindered echo sounding. The echo sounder, a Knudsen Engineering model 1612, used high and low frequencies to distinguish the top and bottom of sediment layers. Data points were collected along predetermined transects spaced 150 feet apart, running from shoreline to shoreline in a north-south direction.
Once fieldwork was completed, the collected data was processed using Hypack Max software. This involved editing the raw sounder data to correct errors such as double reflections and interference from aquatic vegetation. The cleaned data was exported to ArcGIS for further analysis and mapping.
The results of the bathymetric survey revealed that Mercer Lake, a key focus of the lake management plan, covers a surface area of approximately 287 acres and is primarily an oval-shaped impoundment. The lake receives inflow from Assunpink Creek and its tributaries and discharges water westward, eventually reaching the Delaware River, Delaware Bay, and the Atlantic Ocean.
Mercer Lake was found to be relatively shallow, with a mean depth of 8.9 feet and a maximum depth of 18.5 feet. The total volume of water in the lake was estimated at around 2,560 acre-feet, or 834.2 million gallons. The survey also indicated significant sediment deposition in the eastern portion of the lake, with a total sediment volume of approximately 855,325 cubic yards. This pattern is likely due to the lake's role as a settling area for sediment carried by tributary inflows and stormwater discharges, which transport debris, leaf litter, and other materials into the lake.
Below is an image of the Bathymetric Survey that provides a detailed view of the sediment thickness contours measured in feet throughout Mercer Lake:
By establishing a detailed understanding of Mercer Lake's depth and sediment distribution, the bathymetric survey provides a robust foundation for the comprehensive lake management plan, informing long-term management decisions. The bathymetric data collected is also essential for evaluating the need for dredging, understanding aquatic plant colonization patterns, and predicting the lake's response to incoming nutrients, helping to guide restoration and protection efforts.
Hydrologic and Pollutant Loading Analysis is crucial for identifying the sources and impacts of pollutants entering a waterbody. It involves delineating watersheds, assessing hydrologic data, and evaluating nutrient loads.
For Mercer Lake, Princeton Hydro conducted an extensive analysis using tools such as USGS StreamStats and Stroud Research Center’s Model My Watershed®. This study provided a detailed understanding of the water and pollutant dynamics within the Mercer Lake watershed. The map below offers an aerial view of the watershed, illustrating the various types of land cover present within the area:
Runoff varied considerably between different sub-watersheds due to factors like land cover types, land-use consumption, impervious surfaces, and topography. Variations in elevation change also determine the impact runoff has on soil erosion, with steeper slopes causing higher erosion rates, especially if little vegetation is present. The chart below shows the various types of soil coverage in areas throughout the Mercer Lake watershed:
Princeton Hydro also assessed other pollutant sources, including groundwater seepage, streambank erosion, and contributions from residential septic systems. Additionally, the impact of waterfowl, particularly Canada Goose, was evaluated using nutrient loading coefficients. The presence of these birds significantly contributes to phosphorus and nitrogen levels.
The hydrologic budget, representing the water balance of the lake, was calculated by considering inputs such as direct precipitation, overland runoff, tributary inflow, and groundwater seepage. This data is vital for conducting trophic state analyses and determining the feasibility of various in-lake restoration techniques. Internal loading of phosphorus, which occurs when anoxic conditions in the lake's bottom sediments release bound phosphorus into the water, was also analyzed.
Results of the analysis revealed that Mercer Lake, covering 287.1 acres, is influenced by a watershed area of 20,551.4 acres, predominantly consisting of cropland and forested areas. The lake's shallow nature coupled with significant sediment deposition in the eastern portion, underscores the importance of managing both external and internal nutrient loads.
Understanding the hydrologic and pollutant dynamics through this detailed analysis allows for the development of a lake management plan that helps to prioritize management efforts, target the primary sources of pollution, and effectively address HABs.
Monitoring water quality is essential for understanding the existing chemistry of a lake, identifying trends, pinpointing problems, and assessing nutrient levels. It provides critical data that informs management decisions and helps maintain the health and stability of aquatic ecosystems.
For Mercer Lake, Princeton Hydro conducted thorough water quality monitoring from 2021 to 2023. This involved analyzing in-situ, discrete, and plankton data collected over three growing seasons. The monitoring focused on various parameters, including hypolimnetic anoxia and associated phosphorus dynamics, which are key contributors to HABs. The data collected offered a current assessment of the lake’s trophic state and plankton community, providing a baseline to document shifts in water quality in response to future management measures.
The Princeton Hydro team performed 13 sampling events at two consistent stations in Mercer Lake: a deep water station near the dam (ML-1) and a mid-lake station (ML-2). Various parameters were monitored, including water temperature, dissolved oxygen (DO), pH, specific conductivity, chlorophyll a, and phycocyanin, using an In-Situ AquaTROLL 500 meter.
Water samples were collected at both in-lake stations at the surface (0.5 meters) and near the bottom (0.5 meters above the sediment) using a Van Dorn water sampler. Samples were preserved appropriately and transported to the NJDEP-certified laboratory Environmental Compliance Monitoring (ECM) for analysis. The samples were analyzed for total phosphorus (TP), soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP), nitrate-N, nitrite-N, ammonia-N, total suspended solids (TSS), and turbidity. Surface samples were also analyzed for alkalinity, chloride, and hardness.
Additionally, samples were collected for zooplankton and phytoplankton analysis, including species composition, dominant organisms, and relative density. Cyanobacteria (blue-green algae) genera were quantified to estimate cell counts, providing an approximate concentration of cyanobacteria cells per milliliter of water. Samples were also analyzed for the cyanotoxin microcystins using the Abraxis field testing methodology.
The team also evaluated local climatic conditions during the 2021 - 2023 seasons compared to the long-term average. These conditions, including temperature and precipitation, can have significant effects on water quality. The combination of increased precipitation and an increase in temperatures sets the stage for HABs proliferation. The charts below the monthly mean temperatures and monthly precipitation from 2021 – 2023 and the 30-year average; ‘normal’ refers to the monthly average over the 30-year period from 1991 – 2020.
The Water Quality Monitoring analysis revealed several key insights about Mercer Lake's water quality, and indicated that cropland runoff was the most significant source of phosphorus, a key driver of HABs. Hypolimnetic anoxia (the bottom layer of the lake becomes devoid of oxygen) was observed during all three field sampling seasons, contributing to internal phosphorus loading. The water quality monitoring also provided valuable information on the lake’s trophic state and plankton community.
Trophic State Modeling is a method used to assess the productivity of a lake by measuring the levels of nutrients, such as phosphorus, and the resulting biological activity. This assessment helps determine the lake's overall health and informs management strategies. The Trophic State Index (TSI) is a common tool used in this process, calculating index values based on phosphorus concentrations, chlorophyll a levels, and Secchi depths.
For MCPC, Princeton Hydro, utilizing data collected in the field and through lake and watershed modeling, estimated the nutrient status and biological activity of Mercer Lake. Here are a few examples of the models the team utilized:
By leveraging these sophisticated models, Princeton Hydro was able to gain a detailed understanding of Mercer Lake's nutrient dynamics and productivity. Many models were run twice: once for the watershed-based phosphorus load and once for the total combined load. This allowed for a comprehensive assessment of both external and internal nutrient contributions.
To mitigate pollutant loading issues, the Lake and Watershed Management plan outlines a series of Best Management Practices (BMPs) recommendations for implementation throughout the watershed, which include bioretention systems, wetland buffers, riparian buffers, and lakefront aquascaping. Such measures are designed to reduce nutrient loads, improve water quality, and enhance the overall ecological health of the lake and its watershed. By addressing the root causes of nutrient loading and implementing targeted management strategies, the MCPC is continuing their commitment to providing a sustainable and enjoyable recreational experience for park users while safeguarding the lake's ecological integrity.
Stay tuned for more updates as we continue to work with the MCPC on implementing the Mercer Lake and Watershed Management Plan, ensuring the watershed remains a vibrant and healthy resource for generations to come.
Regional watershed planning is crucial for maintaining the health and sustainability of interconnected waterbodies. By considering entire watersheds rather than individual lakes, we can develop more effective and comprehensive strategies to manage water quality, control pollution, and enhance ecological resilience. This holistic approach ensures that all elements within the watershed are addressed, leading to more long-lasting improvements.
Princeton Hydro’s efforts in developing and implementing management plans for Mercer Lake, Curlis Lake, Rosedale Lake, and Spring Lake demonstrate the power of coordinated, science-based planning. By leveraging detailed data and advanced modeling techniques, our team is able to create tailored solutions that meet the specific needs of each lake while contributing to the overall health of the region's aquatic ecosystems.
To read about another project we’re working on in Mercer County, check out our blog about Miry Run Dam Site 21. Through a blend of engineering and ecological enhancements, we are working with MCPC to revitalize 279 acres. With each phase, we edge closer to a vibrant, inclusive space that harmonizes nature and community.
Did you know that New York State is home to a rich tapestry of natural waterbodies, including over 7,600 freshwater lakes, ponds, and reservoirs? Our team recently journeyed to Lake George, New York, to participate in the 41st annual conference of the New York State Federation of Lake Associations (NYSFOLA).
This year’s conference, themed “It Takes a Community to Protect a Watershed,” brought together environmental experts, lake management professionals, students, recreation enthusiasts, watershed advocates, and lake community members to advance the best available information and techniques for protecting and restoring New York’s watersheds. The two-day program featured a diverse exhibitor hall, networking events, a silent auction, a student poster session and a variety of presentations and workshops that combined science, policy, practical applications, and tangible resources.
Princeton Hydro, a proud sponsor of the conference, led two presentations during the “Climate Resilience and Your Lake" segment of the educational program:
Michael Hartshorne, Director of Aquatics, delivered an insightful presentation titled "Impacts of Climate Change on Lake Ecology," which delved into the significant role of climate change in shaping lake ecosystems. During the session, Michael highlighted key factors such as rising water temperatures, heightened frequency and severity of rainfall, depletion of dissolved oxygen, fluctuating patterns of algal blooms, and the migration of invasive species due to changing latitudinal conditions. His presentation underscored the necessity for evolving approaches to lake management in response to these profound ecological shifts.
Dr. Fred Lubnow, Senior Technical Director of Ecological Services, presented "A Survey of the Ecology of Select Lakes and Ponds in Central Park, NYC," which provided an insightful overview of Princeton Hydro's water quality and ecological monitoring efforts conducted across lakes and ponds of Central Park from 2020 to 2023 for the Central Park Conservancy. These assessments revealed elevated nutrient levels driving planktonic algae, filamentous mat algae and in some cases high densities of aquatic plants, prompting the Central Park Conservancy and Princeton Hydro to collaborate on a tailored Management Plan. Fred’s presentation spotlighted the distinct ecological profiles of key sites, addressed the impact of cyanobacteria on both ecological dynamics and recreational usage, and provided practical management methods and techniques.
Additional educational session topics included, Environmental Justice and New York Lakes, Community Leadership for Healthy Lakes in New York State, and iMap Invasive Species Workshop. Click here to view the complete agenda.
Founded in 1983, NYSFOLA is a not-for-profit coalition of lake associations, individuals, and corporate members dedicated to the protection and restoration of New York lakes. Princeton Hydro is the industry leader in lake restoration and watershed management. We have conducted diagnostic studies and have developed management and restoration plans for over 300+ lakes and watersheds throughout the country. Our long-standing partnership with NYSFOLA as a corporate member, annual conference sponsor, and active participant highlights our unwavering commitment to collaborative initiatives aimed at safeguarding our water resources. To learn more about our lake and natural resource management services and how we're contributing to a healthier environment, click here.
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