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[cat_name] => Lake and Pond Management [category_nicename] => lake-and-pond-management [category_parent] => 0 ) [queried_object_id] => 37 [request] => SELECT SQL_CALC_FOUND_ROWS ph_posts.ID FROM ph_posts LEFT JOIN ph_term_relationships ON (ph_posts.ID = ph_term_relationships.object_id) LEFT JOIN ph_term_relationships AS tt1 ON (ph_posts.ID = tt1.object_id) WHERE 1=1 AND ( ph_term_relationships.term_taxonomy_id IN (37) AND tt1.term_taxonomy_id IN (40) ) AND ((ph_posts.post_type = 'post' AND (ph_posts.post_status = 'publish' OR ph_posts.post_status = 'acf-disabled'))) GROUP BY ph_posts.ID ORDER BY ph_posts.menu_order, ph_posts.post_date DESC LIMIT 0, 10 [posts] => Array ( [0] => WP_Post Object ( [ID] => 19087 [post_author] => 1 [post_date] => 2026-03-13 14:32:04 [post_date_gmt] => 2026-03-13 14:32:04 [post_content] => 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. [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.
The Lake Hopatcong Commission, in partnership with Roxbury Township and Princeton Hydro, and with support from the Lake Hopatcong Foundation, has been awarded a $367,000 Water Quality Restoration Grant from the New Jersey Department of Environmental Protection (NJDEP) for the Lake Hopatcong Watershed Basin Enhancement Project.
The project will retrofit an existing stormwater detention basin with a series of green stormwater infrastructure improvements designed to slow, capture, and naturally treat stormwater runoff. The basin project, located between King Road and Mount Arlington Boulevard in Roxbury Township, was identified in the 2021 Upper Musconetcong River Implementation Plan (WIP) as a priority project to reduce non-point source pollution and improve water quality before stormwater enters the lake at King Cove.
"Roxbury is truly thankful for the Lake Hopatcong Commission. Lake Hopatcong is such a valuable resource and the commission’s work alongside Princeton Hydro has preserved a natural treasure," said Shawn Potillo, Mayor of Roxbury. "We are grateful to the NJDEP for their support and award of this grant. This water basin project in Roxbury will help continue the commission’s purpose of keeping the lake a beautiful place to swim, boat, relax, and call home."
A range of improvements will be incorporated including planting native vegetation and managing invasive species to stabilize soils, support wildlife, and naturally filter pollutants before they reach the lake. Erosion and sediment control measures will further protect the area by reducing stormwater scouring and preventing bank degradation.
In addition to on-the-ground restoration, the project emphasizes public education and outreach to promote best management practices and ongoing watershed stewardship among residents and local partners. Project success will be evaluated through water quality monitoring conducted before and after construction, providing measurable data on the project’s effectiveness in improving water quality.
“Lake Hopatcong’s fight against harmful algal blooms requires a united front, where many projects, like retrofitting stormwater basins to capture nutrients before they go into the lake, collectively make a big impact,” said Dr. Fred Lubnow, Senior Technical Director of Ecological Services at Princeton Hydro. “Thanks to the leadership of the Lake Hopatcong Commission and the Lake Hopatcong Foundation, this collaborative approach is driving real progress toward cleaner water, healthier ecosystems, and a more resilient future for New Jersey’s largest lake.”
The basin enhancement project is funded through NJDEP’s Water Quality Restoration Grant Program, which is supported by the U.S. Environmental Protection Agency under Clean Water Act Section 319(h). Along with the state grant, the project includes a $200,000 local match from the Commission, Roxbury Township, and the Lake Hopatcong Foundation, and builds on a $98,000 planning grant awarded by the New Jersey Highlands Council in 2024 that helped prepare the project for implementation and future grant opportunities.
“This project represents an important step forward in improving Lake Hopatcong’s water quality and reducing pollutants that contribute to harmful algal blooms,” said Ron Smith, Chairman of the Lake Hopatcong Commission. “We’re grateful to NJDEP, Roxbury Township, Princeton Hydro, the Foundation and the Highlands Council for their continued partnership in protecting this vital resource.”
The Lake Hopatcong Commission is an independent state agency created in, but not of, the New Jersey Department of Environmental Protection. LHC is recognized as a steward of the lake and watershed. The 11-member Board of State and local appointees include representatives of the four municipalities and two counties surrounding Lake Hopatcong. LHC is responsible for fulfilling the obligations of the Lake Hopatcong Protection Act, to safeguard Lake Hopatcong as a natural, scenic, and recreational resource. To learn more, click here to visit lakehopatcongcommission.org.
For over 30 years, Princeton Hydro has been proud to work alongside the Lake Hopatcong Commission and Lake Hopatcong Foundation in support of the lake’s health and resilience. Through these partnerships, and with the support of numerous funding agencies, a wide range of projects have been implemented to reduce pollutant loads, manage stormwater runoff, address invasive species and harmful algal blooms, and enhance habitat quality—helping to protect both the lake and the communities that depend on it. To learn more about our collaborative efforts, click here.
The Borough of Mountain Lakes has received grant funding from the New Jersey Highlands Council to develop a comprehensive Lake and Watershed Management Plan for nine lakes within the Borough. To lead this effort, the Borough engaged Princeton Hydro, a leader in ecological and engineering consulting. The initiative will focus on characterizing hydrologic and nutrient dynamics within the Borough’s lake systems and watersheds to guide targeted water quality improvement and management strategies.
“Mountain Lakes takes great pride in our lakes, which play an important role in defining our community. Through our partnership with the Highlands Council and Princeton Hydro, we’re taking a proactive, data-driven approach to protecting both the environmental and recreational value of our lakes and waterways, with the goal of preserving these vital natural resources for generations to come,” said Borough of Mountain Lakes Manager Mitchell Stern.
A selection process was undertaken by the Borough of Mountain Lakes, Princeton Hydro, and the New Jersey Highlands Council to define the scope of this Lake and Watershed Management Program. In accordance with Policy 1L2 and Objective 1L2a of the NJHC Regional Master Plan, which establish lake management tiers and prioritize lakes greater than 10 acres for protection and management, nine lakes were selected for the study: Birchwood Lake, Crystal Lake, Wildwood Lake, Sunset Lake, Mountain Lake, Shadow Pond, Olive Pond, Grundens Pond, and Cove Pond. These lakes represent the waterbodies in the Borough and were chosen to ensure the program focuses on areas with the greatest potential impact on water quality, watershed function, and community value.
Princeton Hydro’s work will include watershed modeling, hydrologic and pollutant load analyses, and in-lake and watershed-based water quality monitoring. Once the data is analyzed, Princeton Hydro will develop a General Assessment Report that identifies the primary drivers of eutrophication and outlines a prioritized set of management strategies to effectively reduce nutrient loading and enhance long-term lake health.
“The regional, science-based approach to lake and watershed management has proven to be a powerful tool for municipalities in the Highlands Region,” said Christopher Mikolajczyk, CLM, Senior Manager of Aquatics at Princeton Hydro, Certified Lake Manager, and lead designer for this initiative. “We’re excited to collaborate with Mountain Lakes to help identify cost-effective, data-driven strategies that will enhance water quality throughout the watershed and help safeguard these treasured natural resources.”
The New Jersey Highlands Water Protection and Planning Council (Highlands Council) is a regional planning agency that partners with municipalities and counties in the Highlands Region to promote proactive watershed protection. Established under the New Jersey Highlands Water Protection and Planning Act of 2004, the Council has funded numerous water-quality-related planning initiatives.
Historically, municipalities and private lake associations have managed water quality issues independently. However, taking a coordinated, watershed-based approach enables communities to more effectively address pollution sources, improve water quality, and prevent the spread of invasive species and harmful algal blooms.
Mountain Lakes joins several other Highlands region municipalities that have received Highlands council funding to implement similar lake and watershed management initiatives. In 2019, the Borough of Ringwood became the first municipality in New Jerey to adopt a regional, public-private approach to lake management, partnering with four lake associations across six lakes. Since the completion of the Ringwood plan, NJDEP has funded recommendations from the plan. This model has since inspired additional projects, including watershed assessments for West Milford Township, Rockaway Township, Byram Township, Vernon Township, and Somerset County Parks Commission. Princeton Hydro worked with each agency to develop the respective scope of work to secure grant funding from the Highlands Council.
The New Jersey Department of Environmental Protection (NJDEP) recently announced $8 million in Water Quality Restoration Grants to support projects that reduce nonpoint source pollution, mitigate harmful algal blooms, restore riparian areas, and enhance watershed and climate resilience. Funded through Section 319(h) of the federal Clean Water Act and administered by the DEP's Watershed and Land Management Program, these grants were awarded to municipalities, nonprofit organizations, and academic institutions across the state.
Princeton Hydro is proud to be a partner on five of the 17 funded projects. Our contributions vary by project and encompass activities such as engineering design, water quality assessment, watershed-based planning, and technical support for implementing stormwater and habitat restoration measures. Let's take a deeper look at these collaborative efforts:
The Watershed Institute received $205K in 319(h) grant funding to develop a watershed-based plan for the Assunpink Creek watershed, located within the Raritan River Basin. This watershed spans 11 municipalities across two counties, where varied landscapes and demographics share common challenges such as localized flooding, stormwater management, and water quality degradation, highlighting the need for a coordinated, watershed-wide, science-driven approach.
The plan will evaluate pollution sources and identify large-scale restoration opportunities, including green infrastructure and riparian buffer restoration, to improve water quality and reduce flooding. It will also assess the cost, feasibility, and pollutant reduction potential of proposed measures to ensure practical implementation. Princeton Hydro supported the Institute in developing the grant proposal and planning framework, leveraging our expertise in watershed-based planning to prioritize nature-based solutions that address both water quality and climate resilience. This initiative represents a critical step toward regional collaboration, enabling upstream and downstream communities to work together on strategies that strengthen watershed health, protect public safety, and build long-term resilience.
The Lake Hopatcong Commission (LHC) was awarded $366K to retrofit an existing stormwater detention basin between King Road and Mount Arlington Boulevard in Roxbury Township. This retrofit is part of a larger Watershed Implementation Plan that Princeton Hydro developed in collaboration with LHC, which prioritizes nutrient reduction and stormwater management strategies across the Lake Hopatcong watershed. Over the past several years, LHC has actively implemented multiple elements of this plan to address harmful algal blooms (HABs) and improve water quality.
For this project, Princeton Hydro is providing engineering design and technical oversight to transform the existing basin into a green stormwater infrastructure system that slows, captures, and naturally treats runoff before it enters King Cove. The design incorporates native vegetation, invasive species management, and erosion control measures to stabilize soils and filter pollutants, reducing nutrient loading, which is one key driver of HABs. Public outreach and pre- and post-construction water quality monitoring will ensure performance tracking and measurable improvements. This basin retrofit represents a critical step in a coordinated, science-based approach to restoring ecological health and water quality in New Jersey’s largest lake.
Jefferson Township received $350K in grant funding to develop an Emerging Contaminants Management Plan for Cozy Lake, focusing on cyanotoxins and HABs. Cozy Lake is a 28-acre waterbody within a 1,152-acre sub-watershed that includes both forested (60%) and developed (29%) land. The lake is fed by the Rockaway River at its northern end and a smaller southeastern inlet, with outflow through a dam on the western edge.
The shoreline is primarily residential lawn with minimal emergent wetlands, and several inlets and rock-lined drainage ditches exhibit erosion and lack slope protection, contributing to sediment loading. Princeton Hydro provided early technical input to shape this innovative project with the creation of a comprehensive Jefferson Township Lake and Watershed Restoration and Protection Plan. As part of the plan, Princeton Hydro made recommendations for Cozy Lake, which included enhancing shoreline buffers with native vegetation and installing living shorelines at select properties to stabilize soils, filter stormwater and reduce nutrient loading, improve habitat quality, and enhance community access. These measures, combined with in-lake monitoring and proactive management strategies, will help mitigate HABs and protect ecological and public health.
Rockaway Township received $399K in grant funding to implement elements of its Watershed Implementation Plan, focusing on green infrastructure stormwater management and nutrient reduction to improve water quality. The project will retrofit the municipal complex by converting a rock-lined drainage swale into a vegetated swale with a bioretention basin, designed to filter stormwater runoff and reduce nonpoint source pollutants entering Fox’s Pond and Fox Brook.
Princeton Hydro played a key role in developing the Watershed Implementation Plan, which encompasses 11 private lakes within the Rockaway River watershed, prioritizing critical locations for intervention and designing cost-effective green infrastructure BMPs. This regional approach aligns with strategies recommended by NJDEP and the Highlands Council. The plan included a comprehensive watershed-based assessment to identify and quantify factors contributing to eutrophication, evaluate management measures, estimate costs, and establish an implementation schedule. Princeton Hydro authored the final report, which guided the Township in applying for the Section 319(h) grant and now informs the design and construction of green stormwater infrastructure that will deliver measurable water quality improvements while supporting ecological restoration goals.
Green Trust Alliance (GTA), a nationally accredited land trust and public charity dedicated to accelerating large-scale conservation, received $1.39 million in NJDEP funding to implement green infrastructure improvements at Pinelands Regional High School in Tuckerton, New Jersey. This initiative targets the Tuckerton Creek watershed, which drains into Tuckerton Creek and ultimately flows into Barnegat Bay—a critical estuary spanning 33 municipalities in Ocean County and four in Monmouth County. The retrofit will transform the school’s stormwater detention basin into a multi-functional system that mimics natural hydrology, enhances flow control, and improves water quality locally and in the larger Barnegat Bay watershed.
Working with GTA and GreenVest, Princeton Hydro is serving as the design engineer, applying nature-based engineering and ecological restoration techniques to intercept, evapotranspire, and infiltrate stormwater runoff at its source. In addition to its technical objectives, the effort includes a strong community engagement component and an educational platform for students. By bringing green infrastructure into the school environment, the initiative provides hands-on experience with water resources, stormwater management, and ecological engineering, help to build STEM skills while fostering a deeper connection to the surrounding landscape and an understanding of how natural systems work together to support environmental and community health.
Princeton Hydro also assisted several of these partners in developing successful NJDEP Section 319(h) grant applications, providing technical documentation, conceptual designs, and pollutant load reduction estimates to strengthen the proposals.
To date, the Murphy Administration has awarded more than $33M in Water Quality Restoration grants to improve the health of waterways in all corners of the state. Click here to read about all the 2025 grant funding recipients and their innovative projects.
As NJDEP Environmental Protection Commissioner Shawn M. LaTourette noted in the department's press release, “Enhancing the ecological health of our lakes, rivers, streams and coastal waters has long been a priority of the Murphy Administration. The Department of Environmental Protection is pleased to award these grants that will help our partners advance a variety of strategies to improve the health of these waterways and enhance the quality of life in our communities.”
We are proud to play a continued role in advancing that mission: helping communities implement practical, data-driven solutions that make a measurable difference for New Jersey’s waterways and the people who depend on them. Click here to learn more about our work to protect natural habitat and restore water quality throughout the New Jersey.
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.
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.
As we reflect on the winter of 2023-2024, it's evident that New Jersey experienced another unusually mild season, mirroring the winter of 2022-2023. Notably, Lake Hopatcong, located in Sussex and Morris Counties, remained virtually ice-free throughout the winter, with only a brief period of minor ice formation in early January. This pattern was not isolated to Lake Hopatcong; many lakes across the state and the broader Mid-Atlantic region exhibited similar ice-free conditions. Such conditions can lead to increased algal and plant growth earlier in the year.
Adding to this, from January to early June 2024, 15 of New Jersey's 21 counties recorded precipitation levels 26% to 50% higher than their long-term averages. The remaining six counties, predominantly in the southern part of the state, had precipitation increases of 11% to 25% above their long-term normals. This heightened precipitation is significant as it can transport nutrients, most notably phosphorus and nitrogen, into water bodies, potentially fueling the growth of algae.
Compounding these factors, long-range climate models and trends suggest that the summer of 2024 could rank among the hottest on record. The combination of a mild winter, increased precipitation, and anticipated high summer temperatures sets the stage for conditions similar to those experienced in 2019, a year marked by widespread harmful algal blooms (HABs) in numerous lakes.
HABs, characterized by rapid overgrowths of cyanobacteria, present serious challenges to water quality and aquatic ecosystems. Cyanobacteria, or blue-green algae, naturally occur in aquatic environments but can proliferate rapidly under warm, nutrient-rich conditions. These blooms pose risks to human health, wildlife, aquatic species, local economies, and the overall ecological balance. The interplay between climate change and HABs is undeniable: rising temperatures and altered precipitation patterns foster conditions that exacerbate bloom occurrences.
Given these circumstances, it is crucial for lake managers and water utilities to adopt proactive measures. Early and consistent sampling efforts can detect cyanobacteria and akinetes, dormant spores that contribute to bloom formation. Additionally, reducing nutrient inputs, particularly phosphorus, into waterways is essential to prevent HABs. Princeton Hydro strongly recommends that lake managers, water utilities, and concerned community members closely monitor their lakes, reservoirs, and riverways to stay as proactive as possible in managing these valuable resources.
By raising awareness, fostering collaboration, and implementing effective strategies, we can work towards safeguarding the health and sustainability of our freshwater ecosystems. Together, we can address the challenges posed by HABs and protect the integrity of our water bodies. For more information about HABs, click here.
Dr. Fred Lubnow, Princeton Hydro’s Senior Technical Director, Ecological Services, is an expert in aquatic and watershed management, restoration ecology, community and ecosystem ecology, and the use of benthic macroinvertebrate and fish in-stream bioassessment protocols. Dr. Lubnow has managed hundreds of lake projects and provides technical expertise for a variety of lake and watershed restoration projects.
His experience in lake and reservoir restoration includes the design and implementation of dredging, aeration, chemical control of nuisance species, nutrient inactivation (i.e. alum) and biomanipulation. His experience in watershed restoration includes the design and implementation of structural Best Management Practices (BMPs), the development of Total Maximum Daily Load (TMDL) pollutant budgets, and the design, implementation and analysis of watershed-based monitoring programs.
400 native plants were installed along the western shoreline of Memorial Pond in Mount Arlington, New Jersey. The planting was completed in one day by a team of 20+ volunteers, staff members from Mt. Arlington Department of Public Works (DPW), Lake Hopatcong Foundation, Lake Hopatcong Commission, Princeton Hydro, and a generous community member who volunteered his excavating equipment (and time).
The planting initiative aims to prevent shoreline erosion, promote the growth of native species, increase wildlife habitat, and improve the water quality of Memorial Pond and Lake Hopatcong. Funding for this project was secured through a grant from the New Jersey Department of Environmental Protection, awarded to the Lake Hopatcong Commission in partnership with the Lake Hopatcong Foundation.
Memorial Pond is a 0.3-acre stormwater runoff basin that gradually releases into Glen Brook, which then flows into Lake Hopatcong. The pond receives sheet flow of stormwater from the adjacent road, which contributes to nutrient and sediment loading, thus locally reducing water quality in Memorial Pond and ultimately the waters of Lake Hopatcong.
Memorial Park, which includes Memorial Pond and Glen Brook, was identified by Princeton Hydro and the Lake Hopatcong team as a priority site for improvement, targeting initiatives that reduce pollutants and excessive nutrients entering into Lake Hopatcong.
Additionally, the pond’s steeply-sloped shoreline was bare and only stabilized with large rocks at the base of the banks. In the absence of stabilizing vegetation, the pond’s banks were experiencing erosion, and there was some concern about a few mature trees along the shoreline potentially falling into the pond.
The photos above were taken in April 2023 before the planting initiative.
The plant selection and layout were designed taking into account the steep slope and presence of mature, existing trees as well as focusing on regionally native plant species that will thrive and help stabilize the eroding shoreline. The planting team, led by Princeton Hydro Landscape Architect Jamie Feinstein, RLA and Aquatics Project Manager Pat Rose, was given precise instructions on how to install the plants to eliminate washouts and ensure the root systems can embrace the soil and hold it in place.
A variety of native herbaceous plants and shrubs were chosen for the site, including pennsylvania sedge, slender mountain mint, blue flag iris, sweet azalea, smooth hydrangea, and maple-leaved viburnum.
The plants will help reduce stormwater flow, absorb excess nutrients, prevent erosion, and ultimately decrease sedimentation to the pond, while creating a visually pleasing addition to the park and providing a habitat for pollinators and birds. Overall, this project promotes a healthier and more balanced ecosystem in Memorial Park.
The photos above were taken in July 2023 immediately after the planting initiative.
The installation of these beneficial plants is part of a series of water quality initiatives on Lake Hopatcong funded by a NJDEP Freshwater Harmful Algal Bloom (HAB) Prevention & Management Grant and 319(h) Grant awarded to Lake Hopatcong Commission in partnership with the Lake Hopatcong Foundation.
Additional initiatives included in the watershed implementation and HABs management plan are, the installation of:
floating wetland island (FWI), which are a low-cost, effective green infrastructure solution designed to mimic natural wetlands in a sustainable, efficient, and powerful way. FWIs improve water quality by assimilating and removing excess nutrients; provide valuable ecological habitat for a variety of beneficial species; help mitigate wave and wind erosion impacts; provide an aesthetic element; and add significant biodiversity enhancement within open freshwater environments;
biochar filtration bags, which improve water quality by removing phosphorus from waterbodies. Biochar can be placed in floatation balls, cages, or sacks, which are then tethered along the shoreline and in critical locations throughout the waterbody; and
nanobubble aeration system, which increases the concentrations of dissolved oxygen in the water, prevents stagnation of water, increases circulation, disrupts thermal stratification which provides “through-column” mixing, and minimizes the occurrence of HABs.
“Paired with biochar filters attached to buoys in the pond and continued monitoring and maintenance of the plantings by the DPW, these steps will set a healthy precedent for what can be achieved through working together with funders, local partners, science, and landscape architecture,” said Feinstein, who sourced plant material, provided logistics and co-led the planning and volunteer planting event along with Rose.
Princeton Hydro's Landscape Architect, Cory Speroff PLA, ASLA, CBLP, designed the planting plan, and Will Kelleher and Jackson Tilves from the Aquatics Team participated in the plant installation event with Feinstein.
Princeton Hydro is also authoring and supplying a maintenance manual that provides guidance on seasonal care of the plantings, when to remove the herbivory protection fencing, pruning, watering, and other activities that support the long term success of the planting initiative.
“This collaborative effort to enhance water quality serves as a prime example of how seemingly simple actions can have a meaningful impact on safeguarding our water resources for the benefit of future generations,” said the Lake Hopatcong Foundation.
The photos above from left to right: June 2023 before the planting; July 2023 during the planting (photo by Lake Hopatcong Foundation Executive Director Kyle Richter); and July 2023 immediately after the planting.
Princeton Hydro has been working on Lake Hopatcong, New Jersey’s largest Lake, for 30+ years, restoring the lake, managing the watershed, reducing pollutant loading, and addressing invasive aquatic plants and nuisance algal blooms. To read about some of the other projects we’ve recently worked on at Lake Hopatcong, click here.
Our lakes in New Jersey are an invaluable resource for clean drinking water, outdoor recreation, and agriculture and provide habitat for aquatic flora and fauna. Home to about 1,700 lakes, the “Garden State” is also the most densely populated state. Excess nutrients from fertilizers, roadway pollutants, overdevelopment, and failing septic systems can end up in our lakes and impair water quality. Larger rain events can also cause erosion and instability of streams, adding to the influx of more excess nutrients to our lakes and ponds. Changes in hydrology, water chemistry, biology, and/or physical properties in these complex ecosystems can have cascading consequences that can alter water quality and the surrounding ecosystem. For example, excess nutrients can fuel algal and plant growth in lakes and lead to issues like harmful algal blooms (HABs) or fish kills.
In order to ensure that we protect the overall health of our local waterbodies, it’s important that we look beyond just the lake itself. Implementing holistic watershed-based planning is a critical step in managing stormwater runoff, preventing the spread of HABs, and maintaining water quality. A watershed management plan defines and addresses existing or future water quality problems from both point sources and nonpoint sources of pollutants*. This approach addresses all the beneficial uses of a waterbody, the criteria needed to protect the use, and the strategies required to restore water quality or prevent degradation. When developing a watershed plan, we review all the tools in the toolbox and recommend a variety of best management practices to prevent nutrients from entering lakes or streams. Options include short- and long-term solutions such as green stormwater infrastructure, stream bank stabilization, and stormwater basin retrofits.
To reduce nutrient availability in lakes, one innovative tool in our toolbox is floating wetland islands (FWIs). FWIs are a low-cost, effective green infrastructure solution that are designed to mimic natural wetlands in a sustainable, efficient, and powerful way. They improve water quality by assimilating and removing excess nutrients; provide valuable ecological habitat for a variety of beneficial species; help mitigate wave and wind erosion impacts; provide an aesthetic element; and add significant biodiversity enhancement within open freshwater environments. FWIs are also highly effective in a range of waterbodies from big to small, from deep to shallow.
Typically, FWIs consist of a constructed floating mat, usually composed of woven, recycled plastic material, with vegetation planted directly into the material. The islands are then launched into the lake and anchored in place, and, once established, require very little maintenance.
It estimated that one 250-square-foot FWI has a surface area equal to approximately one acre of natural wetland. These floating ecosystems can remove approximately 10 pounds of phosphorus each year. To put that into perspective, one pound of phosphorus can produce 1,100 pounds of algae each year, so each 250-square-feet of FWI can potentially mitigate up to 11,000 pounds of algae.
In addition to removing phosphorus that can feed nuisance aquatic plant growth and algae, FWIs also provide excellent refuge habitat for beneficial forage fish and can provide protection from shoreline erosion.
Princeton Hydro has been working with Lake Hopatcong, New Jersey’s largest Lake, for 30+ years, restoring the lake, managing the watershed, reducing pollutant loading, and addressing invasive aquatic plants and nuisance algal blooms. Back in 2012, Lake Hopatcong became the first public lake in New Jersey to install FWIs. In the summer of 2022, nine more FWIs were installed in the lake with help from staff and volunteers from the Lake Hopatcong Foundation, Lake Hopatcong Commission, and Princeton Hydro. The lake’s Landing Channel and Ashley Cove were chosen for the installations because they are both fairly shallow and prone to weed growth. The installation of these floating wetland islands is part of a series of water quality initiatives on Lake Hopatcong funded by a NJDEP Harmful Algal Bloom Grant and 319(h) Grant awarded to Lake Hopatcong Commission and Lake Hopatcong Foundation.
Princeton Hydro partnered with the Greenwood Lake Commission (GWLC) on a FWI installation in Belcher's Creek, the main tributary of Greenwood Lake. The lake, a 1,920-acre waterbody located in both New Jersey and New York, is a highly valued ecological, economical, and recreational resource. The lake also serves as a headwater supply of potable water that flows to the Monksville Reservoir and eventually into the Wanaque Reservoir, where it supplies over 3 million people with drinking water.
The goal of the FWI Installation was to help decrease total phosphorus loading, improve water quality, and create important habitat for beneficial aquatic, insect, bird, and wildlife species. The project was partially funded by the NJDEP Water Quality Restoration Grants for Nonpoint Source Pollution Program under Section 319(h) of the federal Clean Water Act. GWLC was awarded one of NJDEP’s matching grants, which provided $2 in funding for every $1 invested by the grant applicant.
Measuring 630+ acres, Harveys Lake is the largest natural lake (by volume) in Pennsylvania and is one of the most heavily used lakes in the area. It is classified as a high quality - cold water fishery habitat (HQ-CWF) and is designated for protection under the classification. Since 2002, The Borough of Harveys Lake and Harveys Lake Environmental Advisory Council has worked with Princeton Hydro on a variety of lake management efforts focused around maintaining high water quality conditions, strengthening stream banks and shorelines, and managing stormwater runoff. Five floating wetland islands were installed in Harveys Lake to assimilate and reduce nutrients already in the lake. The islands were placed in areas with high concentrations of nutrients, placed 50 feet from the shoreline and tethered in place with steel cables and anchored. The FWIs were funded by PADEP.
Working with the Deal Lake Commission (DLC), Princeton Hydro designed and installed 12 floating wetland islands at two lakes in Asbury Park, NJ. In order to complete the installation of the floating wetland islands, our team worked with the DLC to train and assist over 30 volunteers to plant plugs in the islands and launch them into the two lakes. Our experts helped disseminate knowledge to the volunteers, not only about how to install the floating wetland islands, but how they scientifically worked to remove excess nutrients from the water. With assistance from Princeton Hydro, DLC acquired the 12 floating islands – six for Wesley Lake and six for Sunset Lake – through a Clean Water Act Section 319(h) grant awarded by NJDEP.
In addition to the direct environmental benefits of FWIs, the planting events themselves, which usually involve individuals from the local lake communities, have long-lasting positive impacts. When community members come together to help plant FWIs, it gives them a deepened sense of ownership and strengthens their connection to the lake. This, in turn, encourages continued stewardship of the watershed and creates a broader awareness of how human behaviors impact the lake and its water quality. And, real water quality improvements begin at the watershed level with how people treat their land.
For more information on watershed planning or installing FWI in your community, click here to contact us. To learn more about ANJEC, go here.
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