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In urban areas, streams have often been buried beneath streets, buildings, and infrastructure, cutting them off from the natural ecosystem. However, a growing movement towards "daylighting" streams—uncovering and restoring these buried watercourses—has proven to be an innovative solution for improving water quality, reducing flood risks, restoring fish passage, and creating healthier habitats. Princeton Hydro has been at the forefront of these efforts, bringing expertise in ecological restoration and water resource management to daylighting projects across New Jersey.
Daylighting is the process of removing obstructions and impervious surfaces from a buried stream or river, restoring it to a more natural state. Often, streams were diverted underground to make way for urban development. Daylighting involves reversing this process, bringing the water flow back above ground where it can interact with the natural environment. The result is a newly visible, revitalized waterway that reconnects the stream to its surrounding ecosystem. This process not only improves stormwater management but also enhances urban spaces and promotes healthier habitats.
Daylighting streams offers numerous advantages to both the environment and local communities. Some key benefits include:
Princeton Hydro has successfully completed numerous daylighting projects that demonstrate the transformative power of restoring natural waterways. By leveraging innovative engineering and ecological practices, these projects restored the natural flow of waterways and enhanced the surrounding landscape. Let’s take a closer look at two examples:
In the heart of Trenton, NJ, Princeton Hydro undertook a comprehensive stream restoration. The City of Trenton, as part of a larger urban revitalization and brownfield redevelopment project, sought to restore the stream, Petty’s Run, which had long suffered from typical urban afflictions: pollution, flooding, and heavy debris accumulation.
Princeton Hydro developed a green infrastructure design that addressed these challenges holistically. The design included removing from the stream channel heavy debris, contaminated soils, and the concrete remains of previous development. The team also replaced the restrictive upstream road crossing with a pedestrian bridge, enhancing both the stream’s flow and the community’s connectivity. A significant aspect of the project involved daylighting the 250-foot underground portion of Petty’s Run, restoring it to a natural, open flow while creating an adjacent floodplain meadow to manage stormwater and provide habitat.
The project improved stormwater management, enhanced the landscape’s biodiversity, added habitat value, and established a new public green space with walking trails, which now serves as both an ecological asset and a recreational area for the community. This project earned both the Phoenix Award for Brownfield Redevelopment and the Bowman’s Hill Land Ethics Award.
Thompson Park, a sprawling 675-acre recreational area in Middlesex County, NJ, boasts a variety of amenities, including hiking trails, ballfields, and a zoo that is home to over 50 geese and fowl, goats, and approximately 90 deer. The streams within the park faced challenges, particularly in the areas surrounding the zoo’s enclosures, including erosion and compromised water quality.
In order to increase channel stability, decrease erosion, improve water quality and ecological function, and reduce the pollutants originating from the zoo, a stormwater management treatment train was designed and constructed.
Middlesex County Office of Parks and Recreation and Office of Planning, New Jersey Department of Environmental Protection, South Jersey Resource Conservation and Development Council, Middlesex County Mosquito Extermination Commission, Freehold Soil Conservation District, Rutgers Cooperative Extension, Enviroscapes and Princeton Hydro worked together to fund, design, permit, and construct numerous stormwater management measures within Thompson Park.
One of the key project initiatives involved daylighting a section of a 24-inch reinforced concrete pipe (RCP) that had previously conveyed stormwater underground. Daylighting the stream, widen the stream channel, improved stormwater absorption, reduced erosion, helped restore the stream’s natural gradient, and improved aquatic habitat.
This multi-faceted restoration project improved stream function and created a more sustainable environment for both zoo inhabitants, the park’s visitors, and the watershed.
Princeton Hydro’s President and Founding Principal, Geoffrey M. Goll, PE, recently shared his expertise in stream restoration during a "Daylighting Streams: Design & Engineering" webinar hosted by The Watershed Institute. The webinar explored the process of uncovering and restoring buried watercourses. Moderated by Susan Bristol, The Watershed Institute Municipal Policy Specialist, the webinar featured experts Vince Sortman, Biohabitats Senior Fluvial Geomorphologist; Warren T. Byrd, Jr., FASLA, Founding Partner of Nelson Byrd Woltz Landscape Architects & Professor Emeritus, University of Virginia; and Geoffrey. The webinar provided valuable insights into the challenges and benefits of these projects, highlighting the importance of hazard mitigation, maintenance, and community involvement in successful daylighting initiatives. The event underscored the significance of daylighting in enhancing both urban infrastructure and natural ecosystems.
Daylighting streams is a forward-thinking approach to urban water management that brings immense benefits to the environment and local communities. As daylighting continues to gain recognition as an essential tool for watershed restoration, Princeton Hydro remains a trusted leader in the field, combining innovative design with environmental stewardship.
For the first time in over 200 years, the lower Bushkill Creek is now free-flowing and fully reconnected with the Delaware River and, ultimately, the Atlantic Ocean. This tremendous achievement signals a turning point for the ecological health of the Bushkill Creek watershed, supporting the passage of migratory fish species, bolstering ecologically beneficial freshwater mussel populations, reconnecting river habitats that benefit fish and wildlife, and enhancing water quality across the Delaware River Basin, which provides drinking water to millions of people.
"This significant, yearslong restoration effort exemplifies the power of conservation partnerships to achieve profound ecological impact,” said Princeton Hydro President and Founding Principal Geoffrey M. Goll, PE “The restored Bushkill Creek is more than a reconnected waterway—it is a revitalized natural resource that enhances biodiversity, supports community recreation, and contributes to the local economy in sustainable ways.”
Bushkill Creek begins at the foot of Blue Mountain in Bushkill Township, Pennsylvania, and flows for 22 miles through agricultural and suburban areas, including Easton. The limestone stream supports a thriving wild brown trout population and is designated as a “high-quality, cold-water fishery” cherished by anglers and the local community.
Since 2021, Wildlands Conservancy has led the charge to remove five aging dams along Bushkill Creek. While these structures once served industrial and community functions, they had become barriers to fish migration, disrupted the creek’s natural flow, and contributed to localized flooding and water quality issues. Now, with these obstacles cleared, Bushkill Creek flows freely from its headwaters to its confluence with the Delaware River.
Along the creek, the removal of Dam #2 signifies a momentous occasion in its restoration journey, representing the most recent advancement in dam removal efforts.
Led by the Wildlands Conservancy, the restoration of Bushkill Creek involved more than 20 stakeholders, including the Delaware River Basin Commission, Lafayette College, Pennsylvania Department of Environmental Protection, National Fish and Wildlife Foundation, Pennsylvania Department of Conservation and Natural Resources, and Princeton Hydro.
In a press release from the Wildlands Conservancy, President Christopher Kocher, praised the collaborative effort, stating, “This yearslong effort is a win for clean water for all the communities living in connection with the Bushkill Creek. It’s a wonderful example of the power of partnerships, and what community can do for community when nonprofits, local government, and state and federal agencies pool ideas and resources to invest in our treasured natural areas.”
To celebrate this tremendous accomplishment, Wildlands Conservancy, project partners, funders, and community volunteers gathered on October 15, 2024, at Lafayette College’s Karl Stirner Arts Trail.
The event included a volunteer-powered wildflower planting to complete the restoration work at this site, where Dam #1, formerly owned by Lafayette College, had been removed in 2023 with the support of Princeton Hydro. Spanning 90 feet in length and standing 4 feet high, the dam had severely obstructed fish passage, contributed to local flooding, and impaired water quality over time. The college enthusiastically supported the dam's removal, dedicating substantial resources to see the project to completion.
Wildlands Conservancy, a non-profit land trust based in eastern Pennsylvania, is dedicated to the restoration of degraded stream and wildlife habitats, with a primary focus on the Lehigh Valley and the extensive Lehigh River watershed, which spans 1,345 square miles, eventually merging with the Delaware River. For over a decade, Princeton Hydro has been a steadfast partner to Wildlands Conservancy in their mission, collaborating on multiple dam removal projects in the Delaware River Watershed.
The removal of Bushkill Creek Dam #2 is now underway, marking yet another remarkable milestone in the rejuvenation of this treasured limestone stream. This achievement comes on the heels of four successfully completed dam removals since 2021, highlighting the swift progress in the revitalization efforts for Bushkill Creek.
This latest endeavor holds immense significance in facilitating the passage of migratory fish species, such as alewife and American shad, to vital upstream spawning grounds. It contributes to the recovery of ecologically-beneficial freshwater mussels and the bolstering of populations of trout and other resident fish species. And, it marks another important step in returning Bushkill Creek to its natural, free-flowing state.
During a recent site visit, Princeton Hydro President and Founding Principal Geoffrey M. Goll, P.E. took a moment to reflect on the years of hard work that have culminated in this significant milestone. Watch now:
In 2022, Wildlands Conservancy enlisted the expertise of Princeton Hydro to embark on a mission to remove four dams along Bushkill Creek. The successful removal of the Crayola Dam, also known as Dam #4, marked the beginning of this transformative journey. Subsequently, in 2023, Dams #1 and #3 were dismantled. Now, we celebrate the commencement of the removal of Dam #2.
Bushkill Creek flows 22-miles through agricultural and suburban landscape before converging with the Delaware River. Dam #2, situated upstream from the Creek’s confluence with the Delaware River, obstructed fish passage, exacerbated local flooding, and degraded water quality, much like its counterparts. Its removal represents a significant leap forward in the restoration of Bushkill Creek's ecological health.
The ongoing restoration of Bushkill Creek is a testament to the dedication of over 20 stakeholders, including, but not limited to, Wildlands Conservancy, the Delaware River Basin Commission, Lafayette College, Pennsylvania Department of Environmental Protection, National Fish and Wildlife Foundation, Pennsylvania Department of Conservation and Natural Resources, and Princeton Hydro.
Funding for the projects has stemmed from various sources, including a settlement following a fly ash spill from the Martins Creek Power Plant in 2005. This settlement, coupled with contributions from organizations like NFWF’s Delaware Watershed Conservation Fund and Northampton County’s Livable Landscapes program, propelled the initiative forward.
As we celebrate the start of removing Bushkill Creek Dam #2, we anticipate continued progress in the revitalization of this vital waterway. Each dam removed brings us closer to realizing the vision of a thriving, free-flowing Bushkill Creek, benefitting both the environment and local communities.
Wildlands Conservancy, a non-profit land trust based in eastern Pennsylvania, is dedicated to the restoration of degraded stream and wildlife habitats, with a primary focus on the Lehigh Valley and the extensive Lehigh River watershed. Spanning 1,345 square miles, this watershed eventually merges with the Delaware River.
For over a decade, Princeton Hydro has been a steadfast partner to Wildlands Conservancy in their mission, collaborating on multiple dam removal projects in the Lehigh River Valley. With expertise in design, permitting, and oversight, Princeton Hydro has played a pivotal role in the removal of over 80 small and large dams/barriers across the Northeast.
To explore Princeton Hydro's comprehensive fish passage and dam removal engineering services, click here. For more information about Wildlands Conservancy and their conservation efforts, click here.
An extraordinary effort is underway in the Hudson River Valley—the removal of the Maiden Lane Dam. The towering 25-foot concrete structure, originally built for aesthetic purposes on a tributary to the Hudson River, has been impairing aquatic life and causing an array of negative environmental impacts since its construction in the early 1900s. Now, it is the focus of a project that promises to restore vital aquatic habitats.
Join us as we take a deeper look at the Maiden Lane Dam Removal project, an initiative that has been in the planning phase for nearly five years.
Located in the Town of Cortlandt on Furnace Brook, a tributary of the Hudson River, the Maiden Lane Dam was originally built by the former owners of McAndrews Estate. Unlike many dams throughout the country constructed with the primary goals of flood control, hydroelectric power, agricultural irrigation, or navigation of boats, the Maiden Lane Dam was built for aesthetic purposes. Yet the dam's impact extended well beyond its appearance.
The Maiden Lane Dam is the very first dam that fish and aquatic species encounter on Furnance Brook while attempting to travel up the Hudson River to reach foraging habitats and ancestral spawning grounds. The antiquated, unused dam poses a variety of risks to the wildlife restricted by the dam, people who live and recreate near the dam, and the environment surrounding the dam.
McAndrews Estate, along with the dam, was abandoned in the 1960s, and subsequently, Westchester County Parks assumed control of it. Shortly afterwards, the property was condemned.
In 2021, Princeton Hydro secured a contract with Westchester County to develop and finalize the dam removal engineering plans, secure permitting, and facilitate construction bid procurement. The project work also entailed collecting and analyzing sediment samples, conducting geomorphic assessments, and completing an in-depth hydraulic and hydrologic analysis focusing on potential flooding impacts. The collaboration with key stakeholders, including NYSDEC, Westchester County, and the Town of Cortlandt, ensured the feasibility of this ambitious dam removal endeavor.
The collaboration and careful planning set the stage for the much-anticipated removal of the Maiden Lane Dam.
The significance of this project cannot be overstated. Beyond its historical and ecological significance, the Maiden Lane Dam removal will reconnect approximately 1.5 miles of habitat for fish and other aquatic species. It represents a promising chapter in the ongoing efforts to revitalize Hudson River Valley streams and conserve the region's diverse fish and wildlife.
As we eagerly await the completion of the Maiden Lane Dam removal, the vision of restored aquatic habitats and thriving ecosystems shines brightly on the horizon. The journey of the Maiden Lane Dam Removal project is a testament to dedication, collaboration, and the unwavering commitment to the preservation of our natural environment.
Princeton Hydro team members Jake Dittes, PE and Duncan Simpson, PWS presented on Hudson Valley Dam removal during the 2023 National Stream Restoration Conference, hosted by the Resource Institute, a nonprofit organization dedicated to the restoration of America's precious waterways. The event, themed "Stream Restoration 2023: Finding Common Ground,” served as an inspiring backdrop for the broader narrative of stream restoration, showcasing the importance of projects like the Maiden Lane Dam removal in preserving our natural treasures.
The Maiden Lane Dam Removal is part of a larger effort, led by Riverkeeper, to restore migratory fish pathways and fisheries in the Hudson River Watershed.
Princeton Hydro has designed, permitted, and/or overseen the removal of 80+ small and large dams in the Northeast. To learn more about fish passage and dam removal efforts in the Hudson River Valley, click here. To learn more about our engineering services, click here.
In a momentous occasion for environmental conservation, a dam removal on Bushkill Creek is underway, building upon a new era for this cherished limestone stream.
This dam removal marks another important milestone in restoring Bushkill Creek back to its natural, free-flowing state; connecting migratory fish species like alewife and American shad with upstream spawning grounds; and helping to revitalize ecologically-beneficial freshwater mussels colonies and populations of trout and other residential fish species.
Bushkill Creek begins at the foot of Blue Mountain in Bushkill Township, Pennsylvania and flows 22 miles before its confluence with the Delaware River. The limestone stream flows through agricultural and suburban areas, as well as Easton, and supports a large wild brown trout population. It is designated as a “high quality, cold-water fishery” and treasured by anglers and the surrounding community as an important resource in an urban environment.
In 2022, Wildlands Conservancy contracted Princeton Hydro to design, permit, and oversee construction for the removal of four dams along Bushkill Creek. The Crayola Dam, also called Dam #4, was the first of the four dam removal projects to be completed.
The map below shows the location of the next three Bushkill Creek dams being removed:
The demolition and removal of Dam #1 commenced on July 7, 2023 and is scheduled for completion in August. The site labeled as Dam #3 is scheduled for demolition and removal later this year. And, the site labeled as Dam #2, is scheduled for removal in the summer of 2024.
Removing nonfunctional, outdated dams from the Bushkill and allowing the creek to return to a natural, free-flowing state will have myriad ecological benefits.
Dam #1, the first barrier on the Bushkill, is located directly upstream from the Creek’s confluence with the Delaware River. Previous to this removal process, Dam #1 was the upstream limit for migratory fish like alewife, striped bass, and shad.
Dam #1 is owned by Lafayette College in Easton, Pennsylvania. It spans an impressive length of 90 feet, width of 14 feet, and stands 4-feet high. Having been constructed in 1793, the dam had fallen into a state of disrepair, with crumbling concrete impacting the integrity of the streambank retaining wall. Consequently, the dam and associated impoundment have had detrimental effects on the creek's ecosystem, obstructing fish passage, exacerbating local flooding, and degrading water quality. Professors and students of the College have tried for years to effectuate Bushkill Creek dam removals to improve the aquatic environment.
By removing the dam, the project team aims to improve water quality, restore the creek back to its natural flowing state, reconnect river habitats that benefit fish and wildlife, and significantly increase biodiversity for the surrounding watershed. The project work also includes stabilizing the streambank, expanding riparian buffers, planting native trees and shrubs to filter runoff, and installing in-stream structures to restore fish habitat, which has numerous and far-reaching ecological benefits. It is important to note that the project's scope involves minimal disturbance, impacting less than one acre of land surrounding the dam.
The continued effort to restore Bushkill Creek with the removal of Barrier #1, which has been 10-years in the making, serves as a testament to the unwavering dedication displayed by a diverse array of 20+ stakeholders, including Delaware River Basin Commission, Lafayette College, Pennsylvania Department of Environmental Protection, National Fish and Wildlife Foundation (NFWF), Pennsylvania Department of Conservation and Natural Resources, and Princeton Hydro.
According to the Wildlands Conservancy, the initial natural resource damage assessment funding came following a fly ash spill from the Martins Creek Power Plant in 2005. The settlement, which was reached in 2016, totaled $1.3 million, with $902,150 going to the Delaware River Basin Commission for dam removal projects and $50,000 going to the Commission to manage mussel restoration. Additional funding for the overall project came from NFWF's Delaware Watershed Conservation Fund ($2,049,200), and Northampton County's Livable Landscapes program ($100,000).
Princeton Hydro has designed, permitted, and overseen the reconstruction, repair, and removal of 80+ small and large dams in the Northeast. For over a decade, Princeton Hydro has partnered with Wildlands Conservancy to remove dams in the Lehigh River Valley. To learn more about our fish passage and dam removal engineering services, click here. To learn more about Wildlands Conservancy, click here.
The Horseshoe Mill Dam, built in 1827, served as the first barrier to fish passage on the Weweantic River in Wareham, Massachusetts. For over 150 years, migratory fish were unable to reach their breeding grounds upstream due to this structure. However, thanks to the efforts of the Buzzards Bay Coalition and its project partners, the dam was successfully removed between December 2019 and February 2021. As early as April 2021, migratory fish were seen swimming unimpeded from Buzzards Bay to lay their eggs in freshwater upstream. A true success story!
This blog explores the Horseshoe Mill Dam removal project and celebrates the significant milestone in the recovery of fish populations and the restoration of ecological processes in the Weweantic River.
The Weweantic River winds its way through the picturesque landscapes of southeastern Massachusetts, spanning a length of 17.0 miles. This land is the traditional territory of the Wampanoag/Wôpanâak tribes. Derived from the Wampanoag language, Weweantic means "crooked" or "wandering stream."
Originating from the wetlands in Carver, the river flows in a southerly direction meandering through swampy birch and maple forests in Middleborough and Rochester. Eventually, it empties into a Buzzards Bay estuary near the mouth of the Sippican River in Wareham. The river's watershed covers approximately 18,000 acres, with numerous cranberry bogs situated in its upper sections.
Although the Weweantic River historically teemed with fish, the presence of the Horseshoe Mill Dam posed an obstacle to fish passage. The dam, spanning the Weweantic River at the head-of-tide, was built in 1827 to support a metal forge mill. Although it was once part of the infrastructure that supported Wareham’s economy, it had been decommissioned and left crumbling for decades. The defunct dam restricted to tidal inundation, hindered the migration of important fish species, and impacted riverine ecological processes.
The Weweantic River is the largest tributary to Buzzards Bay and provides 20 percent of all freshwater flow into Buzzards Bay. The meeting of salinity and nutrients through the tidal flow creates a vibrant ecosystem. It supports diverse communities of wetland species and a variety of non-migratory and migratory fish species, including river herring, white perch, and American eel. It is also home to the southernmost population of rainbow smelt in the United States, marking a significant change from a century ago when rainbow smelt were found as far south as the Chesapeake Bay. In the 1960s, smelt populations were even present in the Hudson River in New York.
Further highlighting the ecological significance of the Weweantic River and its surrounding watershed are the unique tidal freshwater wetland plant communities. The wetland areas surrounding the Horseshoe Mill Dam site contained two rare wetland plants, Parker's Pipewort (Eriocaulon parkeri) and Pygmyweed (Crassula aquatica), both of which are designated as priority habitats for rare species.
Additionally, situated along the shore of Buzzards Bay and the Weweantic River is the Cromeset Neck & Mark's Cove Marsh Wildlife Sanctuary. The 47-acre wildlife sanctuary consists of three separate parcels within one mile of each other. Salt marsh comprises most of the wildlife sanctuary, and the property also contains approximately six contiguous acres of coastal woodland.
The Horseshoe Mill Dam removal project involved several phases to achieve its restoration goals.
An inspection of the dam, conducted in 2009, rated its condition as unsatisfactory and noted significant concrete deterioration and erosion. The dam also included a former concrete-walled mill race that was in a state of disrepair, with collapsed walls and obstructed channels. The Buzzards Bay Coalition acquired the 10-acre Horseshoe Mill Dam property in 2012 to preserve it, provide public access, and pursue river restoration.
In 2016, the Buzzards Bay Coalition contracted Princeton Hydro to provide an Alternatives Analysis for the Weweantic River restoration project and a Fish Passage Feasibility Study for the dam. The analysis included a thorough site investigation, historical data review, sediment evaluation, hydrologic and hydraulic analysis, and ecological assessment. The five options considered in the analysis were:
The analysis ultimately helped the Buzzards Bay Coalition determine that a complete dam removal offered the most favorable ecological and economic outcomes.
Princeton Hydro, contracted by the Buzzards Bay Coalition, provided site investigation, engineering design, permitting, and construction oversight services for the dam removal. With funding from the Bouchard 120 Natural Resource Damage Trustee Council and collaboration with various agencies, including the U.S. Fish and Wildlife Service and NOAA, the dam removal commenced in December 2019 and was successfully completed in early 2021. Just months later in April 2021, for the first time in 150+ years, migratory fish were once again spotted swimming unimpeded from Buzzards Bay to lay their eggs in freshwater upstream.
Since the completion of the dam removal, Buzzards Bay Coalition Restoration Ecologist Sara da Silva Quintal has been consistently visiting the site and monitoring the positive changes taking place. Her observations include vegetation changes, signs of migratory fish spawning, and the geomorphic evolution of the landscape. She shared a series of Nearmap images that demonstrate how the landscape is positively adjusting to the barrier removal:
The completion of the Horseshoe Mill Dam removal project marks a significant achievement in the restoration of fish passage and the preservation of ecological function in the Weweantic River. Through the collaborative efforts of the Buzzards Bay Coalition, government agencies, and project partners, migratory fish can now freely swim upstream to their breeding grounds.
The restoration effort rejuvenated more than three miles of the Weweantic River and restored migratory fish passage. The dam removal enhanced riverine, wetland, and tidal habitat critical to a diverse group of aquatic, wildlife and plant species. It allowed for the natural extension of upriver habitat for two rare tidal plant species, ensuring their long-term survival. The restoration work also enhanced public access to the area by increasing walking trails and constructing canoe/kayak launches, promoting recreational opportunities, and fostering a deeper connection between people and the river.
In an article written by Kasey Silvia in November 2021, the Vice President for Watershed Protection at Buzzards Bay Coalition, Brendan Annett, was quoted as saying, “Removing this dam has immediately improved the natural functions of the Weweantic, undoing many years of environmental damage and it has already begun to bring the river back to life.”
The success of this project serves as a testament to the importance of collaborative conservation efforts in safeguarding and restoring our natural resources.
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.
According to American Rivers, “more than 90,000 dams in the country are no longer serving the purpose that they were built to provide decades or centuries ago.” As these dams age and decay, they can become public safety hazards, presenting a failure risk and flooding danger. Dams can also be environmental hazards, blocking the movement of fish and other aquatic species, inundating river habitat, impairing water quality, and altering the flow necessary to sustain river life.
Removing nonfunctional, outdated dams has myriad ecological benefits. Dam removal can improve water quality, restore a river back to its natural flowing state, reconnect river habitats that benefit fish and wildlife, and significantly increase biodiversity for the surrounding watershed.
For over a decade, Princeton Hydro has partnered with Wildlands Conservancy to remove dams in the Lehigh River Valley. Wildlands Conservancy, a nonprofit land trust in eastern Pennsylvania, works to restore degraded stream and wildlife habitat with a primary focus on Lehigh Valley and the Lehigh River watershed, which is a 1,345 square mile drainage area that eventually flows into the Delaware River.
Wildlands Conservancy contracted Princeton Hydro to design and permit the removal of two dams on the Little Lehigh Creek. Although it is referred to as the “Little Lehigh,” the 24-mile creek is the largest tributary of the Lehigh River. The dam removals restored the natural stream system, which hadn’t flowed freely in over a century.
Princeton Hydro also worked with Wildlands Conservancy to remove several barriers and three consecutive low-head dams on Jordan Creek, a tributary of the Little Lehigh Creek. Jordan Creek arises from a natural spring on Blue Mountain, and eventually joins the Little Lehigh in Allentown before flowing into the Lehigh River. It drains an area of 75.8 square miles.
Collectively, these dam and barrier removal projects on the Little Lehigh and Jordan Creek reconnected 15+ miles of river; restored fish passage; improved aquatic connectivity, fisheries, and benthic macroinvertebrate and wildlife habitats; reduced nonpoint source stormwater pollution; improved water quality; addressed vulnerable infrastructure; enhanced climate resiliency; and stabilized and restored the creeks’ channels and banks.
Building upon the successes of the Little Lehigh and Jordan Creek barrier removals, Princeton Hydro is again partnering with Wildlands Conservancy to remove three consecutive dams on Bushkill Creek in Easton, PA. The dam removal projects, which are slated for 2023, are part of a large-scale effort, involving a significant number of community and municipal partners, focused on restoring Bushkill Creek and the surrounding watershed.
The Bushkill Creek is a 22-mile long limestone stream that is designated as a “high quality, cold-water fishery.” It supports healthy populations of trout, and is treasured by anglers and the surrounding community as an important resource in an urban environment, spanning several boroughs and townships, eventually flowing into the Delaware River at Easton.
Environmental protection and restoration is a key goal of removing the dams. Removing these barriers will allow important migratory fish species to reach their spawning grounds once again, which has numerous and far-reaching ecological benefits. The project work also includes stabilizing the streambank, planting, and expanding riparian buffers, planting native trees and shrubs to filter runoff, and installing in-stream structures to restore fish habitat.
Princeton Hydro has designed, permitted, and overseen the reconstruction, repair, and removal of over 60 of small and large dams in the Northeast. To learn more about our fish passage and dam removal engineering services, click here. To learn more about Wildlands Conservancy, click here.
This month, we’re celebrating the sixth anniversary of the Hughesville Dam Removal. The removal of the 18-foot-high, 150-foot-long dam not only marked a major milestone in restoring the Musconetcong River, it also led to the speedy return of the American shad (Alosa sapidissima), a species that had been absent from the area for 200+ years.
The Hughesville Dam was constructed by John L. Riegel and the Warren Manufacturing Company in the late-1800s to provide water to power the former paper mill located in Hughesville. The dam, a 12-foot-high timber crib and rock fill dam, spanned the Musconetcong River from Holland Township, Hunterdon County to Pohatcong Township, Warren County. The structure was not in compliance with NJDEP Dam Safety Standards and was creating a blockage to catadromous and local fish passage.
Musconetcong Watershed Association hired Princeton Hydro to investigate, design, permit, and oversee the decommissioning of the Hughesville Dam, and conduct related river restoration work within the Musconetcong River. The Hughesville Dam was the fifth dam on the Musconetcong River designed for removal by Princeton Hydro.
As part of the dam removal project, Princeton Hydro completed a feasibility study in 2012 and initiated designs in 2014 to decommission the spillway and restore the impoundment. To assess potential sediment impacts, vibracoring was conducted and sediment analysis and quantification of the volume of impounded material was completed. Princeton Hydro worked with the NJDEP to assess the quality of sediment and determine its ultimate disposal.
As part of the design, the 21,000 cubic yards was proposed to be hydraulically dredged to adjacent existing on-site lagoons at this now defunct paper mill plant. The pre-existing and proposed hydraulics were assessed to understand impacts to an upstream bridge and downstream flood water surfaces following removal. Geomorphic assessments and utilization of nature-based restoration techniques were utilized to design a new river channel within the former impoundment.
Following the completion of design, applications were prepared for submission to NJDEP’s Land Use Regulation Program and Dam Safety Section, as well as the Hunterdon County Soil Conservation District (Warren County ceded jurisdiction to Hunterdon County). Princeton Hydro also applied for right-of-way permits to reinforce the foundation of an upstream county bridge as well as construct project access from a county road. Following the receipt of permits, Princeton Hydro assisted in the procurement of a contractor and provided construction administration services.
On Thursday, Sept 8 2016, the project team made the first notches in the Dam. Sally Jewell, Secretary of the Interior during that time, toured the project site and held a press conference to commemorate the initial dam breach and celebrate the exciting news. Jewell called the project a “model for collaborative conservation.”
In addition to the Honorable Sally Jewell, NJDEP Commissioner Bob Martin, and U.S. Army Corp of Engineers, Philadelphia District Commander Lt. Colonel Michael Bliss, also participated in the press conference to discuss the importance of the Hughesville Dam removal and dam removal in general.
The entire dam removal took nearly three months, but you can watch the sped-up version here:
The project was supported by many partners and funded largely by the USFWS through the Department of the Interior (DOI) under the Hurricane Sandy Disaster Relief Appropriations Act of 2013.
The removal of the obsolete Hughesville Dam marked another major milestone of restoring the Musconetcong River. The removal is part of a larger partner-based effort led by the Musconetcong Watershed Association to restore the 42-mile Musconetcong - a designated “Wild and Scenic River” – to a free-flowing state.
Removing the dam opened nearly six miles of the Musconetcong to migratory fish, such as American shad, that spend much of their lives in the ocean but return to rivers and their tributaries to spawn. The removal was completed in November 2016 and in the Spring of 2017, schools of American shad were observed above the dam, after 200+ years of absence. Shad are a benchmark species indicative of the overall ecological health and diversity of the waterway.
Other benefits of the dam removal include eliminating a public hazard due to the deteriorating nature of the dam; restoring the natural of floodplain functions and values of the area; restoring native stream substrate and habitat; and increasing river fishing and recreation opportunities.
River herring are diadromous fish, which means they migrate between fresh and salt water. On Long Island in Nassau, New York, they migrate between Mill Pond Creek and the ocean, using Bellmore Creek as a highway. The river herring live much of their adult life in the ocean and travel to the freshwaters of Mill Pond Creek in order to spawn.
There is a dam located at the point where Bellmore Creek meets Mill Pond. When the water level isn’t high enough, the river herring can be blocked from swimming upstream to reach their spawning habitat. This not only has negative implications for river herring species, it also negatively impacts the entire ecosystem. The herring are a vital food source for countless other fish, birds and animals, and play a critical role in transferring marine derived nutrients into surrounding estuarine, freshwater and upland habitats.
River Herring have been documented at the base of the dam at Mill Pond for the past several migration seasons. Bellmore Creek is one of only two-dozen streams on Long Island where remnant runs of this ecologically valuable, diadromous fish still exist.
The project goals not only include increasing river herring spawning habitat, but also are focused on improving the ecological condition of Bellmore Creek, maintaining and enhancing recreational values, and improving site resiliency to climate change and sea level rise.
To provide guidance on the project, Seatuck assembled an advisory committee with representation from Nassau County (dam owner), New York State Office of Parks, NYS Department of Environmental Conservation, Nassau County Soil and Water District, Town of Hempstead, the South Shore Estuary Reserve, Trout Unlimited, The Nature Conservancy, South Shore Audubon, and the Bellmore Civic Association.
On June 8 2021, Seatuck, Nassau County and Princeton Hydro held a virtual meeting to get the public’s input on each of the fish passage designs. Emily Hall, Conservation Policy Advocate for Seatuck, also put together an informative presentation in which she provides a synopsis of Bellmore Creek's history, describes the project goals, and discusses the community engagement process and the results of the public opinion survey. Watch it now:
Additionally, Princeton Hydro completed a site investigation including topographic survey, sediment probing and sampling, and assessment of structures to identify project opportunities and site constraints. Sediment sampling and analysis indicated no major concerns with contamination. By performing analysis of the longitudinal profile, Princeton Hydro determined that the full dam removal (option 3 listed above) was not recommended due to the potential for initiating uncontrolled channel incision below the original river grade into Mill Pond and upstream reaches.
Ultimately, the technical fish ladder (option 2 listed above) was chosen as the most appropriate solution for restoring fish passage to Mill Pond and maintaining existing recreational values. Princeton Hydro is currently developing preliminary engineering design plans for this selected alternative as part of this phase of the project.
The focus on Bellmore Creek is just one of many projects included in Seatuck’s River Revival program, which has sought to clear similarly blocked waterways across Long Island. If you’re interested in learning more about Seatuck’s conservation work and getting involved, click here.
Princeton Hydro has designed, permitted, and overseen solutions for fish passage including the installation of technical and nature-like fishways and the removal of dozens of small and large dams throughout the Northeast. To learn more about our fish passage and dam removal engineering services, click here and check out our blog: Conservation Spotlight: Restoring Fish Passage on the Noroton River.
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