We’re committed to improving our ecosystems, quality of life, and communities for the better.
Our passion and commitment to the integration of innovative science and engineering drive us to exceed on behalf of every client.
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[gallery link="none" columns="4" size="medium" ids="17787,17788,7339,17789"] 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. Understanding the Impacts of Invasive Species 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:
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.
In Warrington Township, Pennsylvania, an innovative ecological uplift initiative is underway at Lion's Pride Park. This project aims to transform a stagnant pond, overrun with invasive species and plagued by water quality issues, into a thriving wetland mosaic. This endeavor, a collaborative effort between Warrington Township, Princeton Hydro, and other stakeholders, promises to not only revitalize the natural environment but also enhance community access and education within the park.
Spanning 47 acres, Lion's Pride Park serves as a green oasis within the Township, offering a range of recreational and educational opportunities for visitors of all ages and abilities.
The pond within the park was in urgent need of restoration - heavy storm events caused the pond to overflow, which created flooding conditions in the park. The local native biodiversity was being threatened by nusiance and invasive species like water chestnut (Trapa natans). The photos below were taken in April 2020.
Princeton Hydro began in 2020 with site investigation and field surveys, including:
The most substantial component for the restoration project was the conversion of the existing pond to an emergent wetland complex to provide habitat for a wide variety of native species. Using the completed existing conditions reports and surveys, Princeton Hydro prepared the conceptual design plan that informed the entire restoration process.
Princeton Hydro Regulatory Compliance & Wildlife Surveys Project Manager Emily Bjorhus, PWS spearheaded the regulatory program for the project, navigating approvals from the Pennsylvania Department of Environmental Protection (PADEP), the U.S. Army Corps of Engineers (USACE), and the Bucks County Conservation District. The permitting process laid the groundwork for the smooth implementation of this design-build restoration project.
The restoration work encompassed various stages, from earthwork and vegetation planting to the installation of ADA-compliant pathways and informational signage. Some of the key project elements, include:
Channel stabilization: Stabilizing the channels within the park, addressing erosion issues, enhancing water flow dynamics, and promoting the establishment of diverse aquatic habitats.
Berm construction: Installing berms to enhance wetland habitat and promote natural floodplain connectivity, contributing to the resilience of the ecosystem to flooding events.
Native vegetation planting: Reintroducing native wetland and riparian plant species to enhance biodiversity and create habitat corridors for wildlife within the park. Planting is expected to take place in the Spring.
Boardwalk installation: Constructing a 6-foot-wide ADA-compliant boardwalk that spanned approximately 230 linear feet, providing visitors with accessible pathways to explore the restored wetland areas.
Through these strategic interventions, the Lion's Pride Park Ecological Restoration Project aims to not only rejuvenate the ecological integrity of landscape but also enrich the recreational and educational experiences of the community. The project, which is slated for 100% completion this Spring, will totally transform the landscape into a diverse wetland complex that fosters native wildlife habitat, mitigates water quality concerns, reduces nonpoint source pollutants discharged to downstream waters, and provides accessible pathways and observation platforms so all community members may enjoy and learn from this restored aquatic setting.
The reclaimed wetland provides additional bird and pollinator habitat and offer visitors a diverse ecosystem to learn from within the park. By fostering a deeper connection to nature and promoting environmental stewardship, this project exemplifies the transformative power of ecological restoration in creating vibrant, sustainable communities.
On March 23, at the 2024 Watershed Congress hosted by the Delaware Riverkeeper Network, Emily will be presenting about the Lion's Pride Park Ecological Restoration Project. Her presentation will offer insights into the regulatory approval and permitting process, takes a deeper dive into the restoration strategies, and showcases the ecological significance of the project. Click here to learn more about the 2024 Watershed Congress.
Emily, a certified Professional Wetland Scientist, is a Project Manager that specializes in environmental regulatory compliance, ecological services and wildlife surveys. She leads federal, state and local environmental permitting processes, NEPA compliance and documentation, Endangered Species Act Section 7 consultations, and Clean Water Act Section 404(b)1 analyses.
The Lion's Pride Park Ecological Restoration Project exemplifies a holistic approach to environmental conservation, community engagement, and public recreation. By repurposing a neglected pond into a vibrant wetland mosaic, this initiative embodies the principles of ecological resilience and inclusive urban planning, and celebrates the transformative potential of ecological uplift projects in fostering healthier, more vibrant communities.
Please stay tuned to our blog for more project updates once planting is completed this Spring. Click here to read more about Princeton Hydro’s robust natural resource management and restoration services.
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