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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[cat_name] => Stream Restoration [category_nicename] => stream_restoration [category_parent] => 0 ) [queried_object_id] => 41 [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 (41) AND tt1.term_taxonomy_id IN (36) ) 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] => 18009 [post_author] => 1 [post_date] => 2025-08-07 19:26:22 [post_date_gmt] => 2025-08-07 19:26:22 [post_content] => We're pleased to announce the release of the "New Jersey Nature-Based Solutions: Planning, Implementation, and Monitoring Reference Guide," a free resource that provides a comprehensive roadmap to incorporating nature-based solutions (NBS) into infrastructure, construction, restoration, and resilience projects across the state. Created by the Rutgers University New Jersey Climate Change Resource Center with support from The Nature Conservancy in New Jersey, the guide compiles current research, case studies, best practices, practical tools, science-based strategies, and funding resources to "inform and empower readers to implement and seek funding for NBS." Click here to view and download the guide now. Inside the Guide As the guide states, "nature-based solutions (NBS) are defined as actions to protect, sustainably manage, and restore natural and modified ecosystems that address societal challenges effectively and adaptively, simultaneously benefiting people and nature." (IUCN 2024) Whether you're a municipal planner, community leader, contractor, public- or private-sector professional, or an academic, new to NBS or experienced in large-scale restoration projects, the guide offers value at every level with practical instruction that spans the full project lifecycle, from planning and permitting to funding and long-term monitoring. While the content is tailored to New Jersey's diverse landscapes, the guide's insights and approaches are broadly applicable to regions with similar ecosystems, from Massachusetts to Virginia. The guide equips readers with:
We're pleased to announce the release of the "New Jersey Nature-Based Solutions: Planning, Implementation, and Monitoring Reference Guide," a free resource that provides a comprehensive roadmap to incorporating nature-based solutions (NBS) into infrastructure, construction, restoration, and resilience projects across the state.
Created by the Rutgers University New Jersey Climate Change Resource Center with support from The Nature Conservancy in New Jersey, the guide compiles current research, case studies, best practices, practical tools, science-based strategies, and funding resources to "inform and empower readers to implement and seek funding for NBS."
Click here to view and download the guide now.
As the guide states, "nature-based solutions (NBS) are defined as actions to protect, sustainably manage, and restore natural and modified ecosystems that address societal challenges effectively and adaptively, simultaneously benefiting people and nature." (IUCN 2024)
Whether you're a municipal planner, community leader, contractor, public- or private-sector professional, or an academic, new to NBS or experienced in large-scale restoration projects, the guide offers value at every level with practical instruction that spans the full project lifecycle, from planning and permitting to funding and long-term monitoring. While the content is tailored to New Jersey's diverse landscapes, the guide's insights and approaches are broadly applicable to regions with similar ecosystems, from Massachusetts to Virginia.
The guide also includes insights on how to address equity considerations and foster meaningful community engagement, helping users implement NBS that are both impactful and inclusive.
Princeton Hydro was proud to contribute technical expertise to this important effort. Our Director of Restoration & Resilience, Christiana L. Pollack, CERP, CFM, GISP, participated on the guide's steering committee, and our team provided informational resources, including content and case studies on invasive species management, wetland and floodplain enhancement, and dam and culvert removal to restore rivers and improve fish passage. These contributions along with those from many other participants, reflect the collaborative nature of the guide and the collective commitment to advancing NBS across the state.
The guide's easy-to-follow format includes four key sections:
Whether you're just beginning to conceptualize a project or deep into project implementation, this guide is an invaluable addition to your toolbox. We encourage you to explore, download, and share it widely! Click here to access the guide now.
In the late 1920s, the U.S. government began allocating funds for road construction in U.S. national forests. This led to hundreds of thousands of culverts being built and installed across the country for the purpose of moving water quickly and efficiently underneath the roadways to prevent flooding, minimize erosion, and provide pathways for stormwater.
However, culverts have had an unintended and significant consequence: they block the migration routes of some fish and aquatic organisms.
Culverts that are undersized, improperly placed, or designed with smooth featureless surfaces can impede or totally block fish and aquatic species from passing. Culverts with extremely high velocity flows make it incredibly difficult for aquatic organisms to navigate upstream, and extremely low velocity flows make it hard for fish to pass in either direction. The high-velocity flows can erode the stream channel immediately downstream of the culvert, which can leave the culvert pipe perched. This elevation above the water channel makes it impossible for organisms to pass through. Debris can also collect in the culvert, not only blocking fish passage, but water as well.
In addition to blocking the upstream passage of fish and other aquatic species, some culverts disrupt the normal stream movements of some macroinvertebrates, which are key components of these stream ecosystems, an important food source to countless species, and play a critical role in the cycling of energy and nutrients throughout stream ecosystems. Disruptions to the movement and dispersal of stream macroinvertebrates can reduce available habitat, lead to genetic isolation of some populations, and cause extirpation of critical species. When populations splinter, it causes a reduction in genetic diversity, which can lead to the spread of more invasive species and many other ecological issues.
While culverts serve an important function in road construction and flood prevention, their impact on aquatic organisms must be taken into consideration. Finding solutions that both allow for efficient water flow and enable safe aquatic migration is crucial in preserving the health of our waterways and their ecosystems.
A shift in the 1980s recognized the importance of redesigning road-stream crossings for several reasons, including restoring aquatic organism passage and maintaining flood resilience. Between 2008 and 2015, U.S. Forest Service (USFS) partnered with more than 200 organizations in the Legacy Roads and Trails Program to replace 1,000+ culverts across the country. The aim of the program was to upgrade culverts to emulate natural streams and to allow fish and wildlife to pass more naturally both upstream and downstream.
Replacing culverts with structures that better facilitate the movement of both water and aquatic organisms has benefits beyond restoring critical ecosystems and improving biodiversity. Ecological restoration creates jobs, stimulates outdoor recreation and local economic activity, and generates long-term economic value.
Princeton Hydro has a strong history in designing connectivity-friendly road-stream crossings and restoring/replacing outdated culverts. Our team of engineers and scientists has been directly involved with hundreds of stream and ecosystem restoration projects throughout the Northeast.
For several years, Princeton Hydro has partnered with NY-NJ Harbor & Estuary Program (HEP) to plan and design for aquatic connectivity through climate-ready infrastructure. Created by the U.S. Environmental Protection Agency (USEPA) at the request of the governors of New York and New Jersey, HEP develops and implements plans that protect, conserve and restore the estuary, and aquatic connectivity is a key focus area for HEP and its partners.
Most recently, HEP partnered with Princeton Hydro to address hydraulic capacity issues at priority road-stream crossings in New Jersey’s South River and Lower Raritan River watersheds. The Princeton Hydro team developed a 30% engineering plan for a priority road-stream crossing – the Birch Street crossing over the Iresick Brook in Old Bridge, NJ.
Iresick Brook is upstream from Duhernal Lake, located at the end of the free-flowing South River, which feeds into the Raritan River, and ultimately flows into Raritan Bay. Duhernal Lake is dammed at the outlet so there is little to no connectivity downstream from the Iresick Brook sub-watershed. The watershed is highly dendritic (meaning the drainage pattern follows a tree-like shape) with many small streams running through it, some of them ephemeral.
The Iresick Brook 5 (IB5) culvert, located in Old Bridge Township, New Jersey, is an undersized double culvert in poor condition with an eroding streambank. This culvert was chosen as a restoration priority primarily due its inadequate sizing (both pipes are only 3-feet in diameter). The outdated infrastructure blocks the passage of fish and other aquatic organisms, and it can only accommodate a 50-year storm event.
Once the IB5 culvert was identified as the priority site, Princeton Hydro completed a site investigation, which included a geomorphic assessment, site observations, and simplified site survey of the channel alignment, profile, and cross sections both upstream and downstream of the culvert.
At the time of the survey, flow was only a couple inches deep in the channel and incredibly slow-moving, especially in the upstream reach. Despite the low flow at the time of the survey, during storm events, the stream experiences extremely high velocities. The undersized culvert creates hydraulic constriction and subsequently a velocity barrier that prevents passage. Additionally, when the high-flow stream water is forced through the small pipes, it creates a firehose effect, which has led to the formation of a 60-foot-long scour hole at the culvert outlet. Substrate from the scour hole has been washed downstream, forming an island of large sand and small gravel.
Approximately 155 feet upstream of the culvert is a channel-spanning v-notch weir comprised of a combination of sheet pile and timber. The weir appears to be a historical stream gauge that is highly degraded and creates an artificially perched channel. The upstream channel also contains woody debris, which gets caught at the culvert, blocking water flow and organism passage.
For the design process, Princeton Hydro used the USFS Stream Simulation Design, an gold-standard ecosystem-based approach for designing and constructing road-stream crossings that provide unimpeded fish and other aquatic organism passage through the structure. The Stream Simulation, a required standard on USFS road projects, integrates fluvial geomorphology concepts and methods with engineering principles to design a road-stream crossing that contains a natural and dynamic channel through the structure so that fish and other aquatic organisms will experience no greater difficulty moving through the structure than if the crossing did not exist.
The design also incorporated utility constraints (gas line, sewer line, drinking water main, and stormwater outlet), a longitudinal profile assessment, channel capacity and slope analysis, and a simplified hydrologic & hydraulic assessment.
Ultimately, Princeton Hydro recommended that HEP replace the existing culvert with a Contech Precast O-321 culvert, or similar alternative. The proposed design increases the culvert opening area and allows for significant increases in flow capacity. This culvert replacement project has the potential to reduce local flood risk and restore aquatic organism passage to the reach of Iresick Brook.
Aquatic connectivity is crucial for improving healthy aquatic ecosystems and managing severe storms and flooding. Increases in rainfall due to climate change makes investing in these improvements even more of a growing priority. With so many culverts in place, it can be difficult to know which culvert restoration projects to prioritize.
We worked with HEP to create a toolkit for addressing problematic road-stream crossings. The easy-to-use matrix helps to prioritize potential projects and identify solutions for problem culverts and relative cost solutions.
The toolkit was just recently released to the public with the hope that it will be used as a template to promote the development of more resilient and environmentally-friendly infrastructure.
Click here to get more info and download.
In October 2021, the largest stream restoration in Maryland was completed. Over 7 miles (41,000 linear feet) of Tinkers Creek and its tributaries were stabilized and restored.
The project was designed by Princeton Hydro for GV-Petro, a partnership between GreenVest and Petro Design Build Group. Working with Prince George’s County Department of the Environment and coordinating with the Maryland-National Capital Parks and Planning Commission, this full-delivery project was designed to meet the County’s Watershed Implementation Plan total maximum daily load (TMDL) requirements and its National Pollutant Discharge Elimination System Municipal Separate Storm Sewer System (MS4) Discharge Permit conditions.
Today, we are thrilled to report that the once highly urbanized watershed is flourishing and teeming with life:
We used nature-based design and bioengineering techniques like riparian zone planting and live staking to prevent erosion and restore wildlife habitat.
10,985 native trees and shrubs were planted in the riparian area, and 10,910 trees were planted as live stakes along the streambank.
For more information about the project visit GreenVest's website and check out our blog:
The Aquetong Creek Restoration Project is situated within the former basin of Aquetong Lake, which was a 15- acre impoundment formed in 1870 by the construction of an earthen dam on Aquetong Creek. The cold-water limestone spring, which flows at a rate of about 2,000 gallons per minute at approximately 53ºf, is known to be the largest of its kind in the 5-county Philadelphia region, and one of the largest in the state of Pennsylvania.
In 2015, the Township of Solebury commenced the restoration of Aquetong Spring Park, first with a dam breach followed by a large stream restoration, reforestation, and invasive species removal. In September, the park was officially reopened to the public following a ribbon cutting ceremony. The event featured a blessing from the Lenni-Lenape Turtle Clan, the original inhabitants of the land.
Prior to European settlement, the Lenni-Lenape Tribe inhabited a village close to the spring and designated the spring “Aquetong”, meaning “at the spring among the bushes." After an outbreak of smallpox, however, the tribe abandoned the village. William Penn acquired Aquetong Spring in the early 1680’s as part of his peaceful treaty with Lenni-Lenape. The park land transferred hands many times before it was owned by Aquetong Township.
The dependability of the water flow made the Aquetong Creek an ideal location for mills. As of the early 1800’s, Aquetong Spring is known to have supplied enough water to turn two grist mills regularly throughout the year, and to have concurrently powered numerous mills including a paper mill, a fulling mill, two merchant mills, four sawmills, and an oil mill.
Around 1870, the 15-acre Aquetong Lake was created by constructing a dam at the east end of the property. This provided additional power for the local mills and a recreation area for the public. A fish hatchery was constructed at the base of the spring outfall, portions of which can still be viewed today. Shad, brook trout, and terrapin turtles were raised in the hatchery, which was available for public viewing at a cost of 25 cents per person.
Then, in 1993, the Pennsylvania Fish and Boat Commission acquired the property. A few years later, with the support of Bucks County Trout Unlimited, Solebury Township began negotiating to obtain ownership of the site. Around 1996, the State performed emergency repairs on the dam; a six-foot section of the outlet structure was removed in order to take pressure off the aging barrier. This lowered the level of the lake and added about 80 feet of wetlands to the western shoreline. However, it was recognized that a complete repair of the dam could cost over $1 million and might not be the best choice for the environment.
In 2009, after almost 15 years of negotiations, Solebury Township gained control of the property, with the goal of preserving this important natural resource. It purchased the lake and surrounding properties from the state and obtained a 25-year lease. The Township’s total costs were substantially reduced because it received a large credit in exchange for its commitment to repair the dam in the future, as well as funding from the Bucks County Natural Areas Program toward the purchase.
Following the purchase, the Township engaged in a five-year process of community outreach and consultation with environmental experts in which it considered alternatives for the Aquetong Lake dam. Choices included rebuilding the dam in its then-current form, creating a smaller lake with a cold-water bypass into Aquetong Creek, or breaching the dam and restoring a free-flowing stream. Ultimately, recognizing that the lake was a thermal reservoir which introduced warm water into Aquetong Creek and eventually into the streams and river, the Township decided to breach rather than restore the dam, and return the site to its natural state.
The Aquetong Restoration Project got underway in 2015, and Solebury Township breached the historic mill dam in Aquetong Spring Park to convert the former lake into a natural area with a free-flowing, cold water stream capable of supporting native brook trout.
After the dam breach, areas of active erosion were observed along the mainstem and a major tributary of Aquetong Creek. The steep, eroding banks, increased the sediment load to the Creek's sensitive aquatic habitat.
As with most dam removal projects, a degree of stewardship is necessary to enhance the establishment of desirable, beneficial vegetation. Additionally, Solebury Township wanted to control invasive species in Aquetong Spring Park and replant the project area with native species.
The Township secured funding to construct riparian buffers, implement streambank stabilization measures, establish trout habitat structures within the mainstem and its tributary, control invasive species, and implement a woodland restoration plan. The project was funded by a $250,000 grant from the PA Department of Conservation and Natural Resources, with an equal match from the Township. Additional grants for the project were provided by the PA Department of Community and Economic Development and the National Fish and Wildlife Foundation.
Solebury Township contracted Princeton Hydro to design the stabilization of the stream channel and floodplains within the former impoundment, monitor the stream and wetlands before and after implementation, and obtain the permits for the restoration of the former impoundment. Princeton Hydro team members designed the restoration of the main channel and tributary to reduce channel and bank erosion while supporting the brook trout habitat.
After gathering and reviewing the existing data for the site, Princeton Hydro conducted field investigations to inform and guide the final design including surveying cross sections and performing fluvial geomorphological assessments of the existing channel. Pebble counts were performed, cross sections were analyzed, and existing hydrological data was reviewed to inform the design. Simultaneously, an invasive species control and woodland restoration plan was developed for the park.
Data collected from the site was used to develop a geomorphically-appropriate, dynamically-stable design. The proposed channel design included excavation of impounded sediment to create stable channel dimensions, the addition of gravel, cobble, and boulder substrate where original/existing channel substrates were absent or insufficient, and the installation of large wood features to create aquatic habitat and enhance stability of channel bed and banks.
The banks and riparian corridor were vegetated with native seed, shrubs and trees to ultimately create a wooded, shaded riparian buffer. The design ultimately stabilized the streambanks with features that double as trout habitat and replanted the surrounding park with native vegetation.
The project was replanted with an incredibly diverse set of native species that included:
In addition to restoring the stream in the former impoundment, as a part of its Strategic Master Plan for Aquetong Spring Park, Solebury Township expanded its focus of the restoration project to include another 20 acres of forested land.
For this, Solebury developed a Woodland Restoration Plan which identified over 1,000 diseased forest trees, composed mostly of ash (Fraxinus sp.) and black walnut (Juglans nigra). It was the Township’s objective to remove the hazardous trees, re-establish a native woodland community, and establish an invasive species management program.
The trees removed as a part of this effort were repurposed for the stream restoration project and used for habitat features, stream stabilization measures, and park features (i.e. benches).
Princeton Hydro also provided stormwater design support for adjacent areas in Aquetong Spring Park, including multiple stormwater connections to the main tributary. After completion, Princeton Hydro provided bid assistance, developed a probable cost, drafted technical specifications, and produced a bid package to assist Aquetong Township in bringing the project to construction.
This restoration success could not have been possible without the hard work of so many dedicated project partners: Aquetong Spring Advisory Council, Bucks County Trout Unlimited, Solebury Township, Aquetong Township, Simone Collins Landscape Architects, PA Department of Conservation and Natural Resources, PA Department of Community and Economic Development, the National Fish and Wildlife Foundation, Lenni-Lenape Turtle Clan, and Princeton Hydro.
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Princeton Hydro specializes in the planning, design, permitting, implementing, and maintenance of ecological rehabilitation projects. To learn more about our watershed restoration services, click here. To learn about some of our award-winning restoration projects check out our blogs about the Pin Oak Forest Conservation Area freshwater wetland restoration project:
Freshwater mussels are among the oldest living and second most diverse organisms on Earth with over 1,000 recognized species. Here in the eastern part of the U.S., we have more species of freshwater mussels than anywhere in the world. Unfortunately, freshwater mussels are one of the most rapidly declining animal groups in North America. Out of the 300 species and subspecies found on the continent, 70 (23%) have been federally listed as "Threatened" or "Endangered" under the Endangered Species Act. And, in the last century, over 30 species have become permanently extinct. So, why are populations declining so fast?
Freshwater mussels are filter feeders and process large volumes of the water they live in to obtain food. This means of survival also makes them highly susceptible to industrial and agricultural water pollution. Because they are constantly filtering water, the contaminants and pathogens that are present are absorbed into the mussel’s tissues. As such, mussels are good indicators of water quality and can greatly contribute to improving water quality by filtering algae, bacteria and organic matter from the water column.
Not only do freshwater mussels rely on water quality, they are dependent on fish and other aquatic organisms for reproductive success. In order for a freshwater mussel to complete the reproduction process, it must “infect” a host fish with its larvae. The method depends on the specie of mussel. Some species lure fish using highly modified and evolved appendages that mimic prey. When a fish goes into investigate the lures, the female mussel releases fertilized eggs that attach to the fish, becoming temporarily parasitic. Once the host fish is infected, it can transfer the mussel larvae upstream and into new areas of the river.
Both habitat loss from dam construction and the introduction of pesticides into the water supply has contributed to the decline of freshwater mussels. With approximately 300 mussel species in the U.S. alone, a critical component of restoring and revitalizing mussel populations is truly understanding their biology, which begins with the ability to properly differentiate each species and properly identify and catalog them. Princeton Hydro’s Senior Scientist Evan Kwityn, CLP and Aquatic Ecologist Jesse Smith recently completed the U.S. Fish and Wildlife Service's Fresh Water Mussel Identification Training at the National Conservation Training Center in West Virginia.
Through hands-on laboratory training, Evan and Jesse developed their freshwater mussel identification skills and their knowledge of freshwater mussel species biology. Course participants were tasked with mastering approximately 100 of the most common freshwater mussel species in the United States. They also learned about proper freshwater mussel collection labeling, the internal and external anatomy and meristics of a freshwater mussel, and distributional maps as an aid to freshwater mussel identification.
In a recently published press release, Tierra Curry, a senior scientist with the Center for Biological Diversity was quoted as saying, “The health of freshwater mussels directly reflects river health, so protecting the places where these mussels live will help all of us who rely on clean water. This is especially important now, when we see growing threats to clean water from climate change, agriculture and other sources.”
Princeton Hydro is committed to protecting water quality, restoring habitats, and managing natural resources. Read about some of our recent projects and contact us to discuss how we can help you.
To learn more about freshwater mussels, check out this video from U.S. Fish and Wildlife Service:
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