“2018 Land Ethics Award of Merit” awarded to Mullica River Wetland Mitigation Project

At the 18th Annual Land Ethics Symposium, which is presented by Bowman’s Hill Wildflower Preserve, Princeton Hydro and GreenVest, LLC were honored with the “2018 Land Ethics Award of Merit” for our restoration work at the Mullica River Wetland Mitigation Site.

We teamed up to restore the natural wetland hydrology on a 34-acre parcel of land which was heavily impaired and intensely manipulated for cranberry production over the last century. The area was home to a network of earthen berms surrounding cranberry cultivating bogs, where water onsite was managed through a series of ditches and water control structures set into the berms. The cranberry operation was bordered mostly by an Atlantic white cedar dominated swamp.

“Thank you to Bowman’s Hill for honoring this successful wetland restoration project,” said Mark Gallagher, Vice President of Princeton Hydro. “Through our partnership with GreenVest, we transformed a degraded cranberry bog into thriving emergent and forested wetlands, and restored historic headwater stream channels. These restored wetlands are providing invaluable habitat to a variety of threatened and endangered species in New Jersey, including the Pine Barrens Treefrog and Barred Owl.” 


While this site was degraded, it still contained four state listed species, including the state-endangered Timber Rattlesnake and the Pine Barrens Tree Frog, making it a priority site for restoration. The presence of these species influenced the design as it included provisions to incorporate habitat elements for these species.

Through the implementation of restoration activities focused on removing the site’s agricultural infrastructure, Princeton Hydro and GreenVest were able to restore a natural wetland system on the site. In addition, the restoration project reconnected the site to its floodplain and re-established a natural stream channel. The expansive, flat and wide floodplain wetland complex of the Alquatka Branch of the Mullica RIver provides floodplain connectivity for relatively frequent storm events and allows for a sustainable floodplain wetland complex in the former cranberry bog cells.

The completed project incorporated a balance of both ecological and human health and safety benefits. Additionally, the project involved innovative restoration techniques that required building consensus among local watershed protection groups and state and regional regulators, including New Jersey Department of Environmental Protection and the New Jersey Pinelands Commission. In the end, the project restored 34 acres of a highly functioning forested wetland/upland complex and reestablished 1,600+ linear feet of historic headwater stream channels.

Princeton Hydro would like to thank Bowman’s Hill Wildflower Preserve for both the award and for a organizing another successful Land Ethics Symposium. The conference focused on ways to create low-maintenance, economical and ecologically balanced landscapes using native plants and restoration techniques. Princeton Hydro was a proud “Friends Sponsor” of the event.


This Month’s Events: March Update from Princeton Hydro

Princeton Hydro is proud to participate in a number of exciting conferences throughout March. The conferences, which take place in Pennsylvania, New Jersey and Virginia, cover a wide variety of topics centered around protecting water resources.

March 2: New Jersey Conservation Rally

The 22nd Annual NJ Land Conservation Rally is a one-day educational conference about preserving open space and farmland in New Jersey. The event consists of training workshops, roundtable discussions, a keynote speech from David Case, author of “Nature of Americans,” exhibitors, and a farmers market.

Princeton Hydro, a proud sponsor of the rally, is giving two presentations:
  • “Recognizing The Power of Dam Removal To Reconnect & Restore Our Ecosystem”
    The Nature Conservancy ’s River Restoration Manager Beth Styler Barry and Princeton Hydro’sDirector of Engineering Services Mary Paist-Goldman , P.E. will present the most effective ways to approach a comprehensive, all-inclusive dam removal in New Jersey, with particular emphasis on the Musconetcong Watershed.
  • “Nonprofit Social Media Hacks”
    Rally Planning Committee member Lindsay McNamara and Communication Strategist for Princeton Hydro Dana Patterson present ways to punch up your social media presence. The course is designed for social media beginners and experts alike, and will cover cross-channel techniques to help increase engagement, event attendance, and social buzz around your organization.



March 4 – 6: Virginia Water Conference

Held by the Virginia Lakes and Watershed Associationand the Virginia Floodplain Management Association, the Virginia Water Conference will host 400 participants, and will include exhibits and breakout sessions on topics ranging from floodplain management to dam safety to water resource engineering.

Princeton Hydro’s Dr. Fred Lubnow, Director of Aquatic Programs, and Michael Hartshorne, Senior Limnologist, are conducting a Water Quality and Quantity breakout session titled,  “A Limnological Assessment of a 250-Acre Impoundment in Virginia for the Consideration of Nutrient Inactivation.”



March 7 – 8: PA Lake Management Society Conference

The Pennsylvania Lake Management Society is hosting its 28th annual conference during which lake professionals, students, recreation enthusiasts, lakeside residents and community members will come together to explore a variety of topics related to managing lakes and reservoirs. Visit the Princeton Hydro booth to discuss the latest advancements in pond, lake and watershed management.

The conference offers a collection of professional presentations, workshops and panel discussions. Princeton Hydro is giving two presentations during the conference:

  • “Continued Management of Hydrilla in Harveys Lake, Luzerne County, Pennsylvania”
    Lead by Michael Hartshorne, Senior Limnologist, and Scott Churm, Associate: Director of Aquatic Operations
  • “Conducting a Nutrient Inactivation Treatment for Internal Phosphorus Load Control for a Small Glacial Lake in Northern Pennsylvania”
    Lead by Dr. Fred Lubnow, Director of Aquatics Programs



March 10: Schuylkill Watershed Congress

The Watershed Congress is an annual event that seeks to advance the best available information and techniques for protecting and restoring watersheds by combining science, policy, and practical applications into one program.

The one-day conference offers a keynote discussion on Landscape-Scale Forest Loss in the Delaware Basin, 21 concurrent sessions covering a broad range of watershed topics, poster sessions and exhibits. Dr. Fred Lubnow‘s breakout session, titled “Ecology/Management of Cyanotoxin Producing Blue-Green Algae in the Schuylkill River,” reviews the basic ecology of nuisance blue-green algae and how to monitor, manage and prevent cyanotoxins particularly in potable water supplies.



March 15: Land Ethics Symposium

The theme for this year’s 18th Annual Land Ethics Symposium, which is presented by Bowman’s Hill Wildflower Preserve, is “Creative Approaches for Ecological Landscaping.” The conference will focus on ways to create low-maintenance, economical and ecologically balanced landscapes using native plants and restoration techniques.

Participants can take part in presentations, for which continuing education credits are available, on topics, including Installation and Management of Stormwater Basins, Landscaping for Carbon Storage and Resilience, and Watershed Restoration. The conference also offers a variety of networking events and an exhibitor hall. Princeton Hydro, a “Friends Sponsor” of the event, will have an exhibitor table. We hope to see you there!



March 19: SAME Philadelphia Post Small Business Conference

The Philadelphia Post is hosting its 12th Annual Small Business Conference and Industry Day, which aims to promote engagement between agency, industry, and small businesses. The program consists of networking events, small business exhibits, a variety of speakers and much more.

The Society of American Military Engineers (SAME) gives leaders from the A/E/C, environmental, and facility management industries the opportunity to come together with federal agencies in order to showcase best practices and highlight future opportunities for small businesses to work in the federal market. If you’re in attendance, please stop by the Princeton Hydro booth.


Lake Mohawk Country Club Publication Features Princeton Hydro

The Lake Mohawk Country Club (LMCC) recently published an article in The Papoose, the organization’s newsletter, that featured Princeton Hydro Founder Dr. Steve Souza and announced that he received the North American Lake Management Society’s “2017 Lake Management Success Stories Award” for his work with Lake Mohawk.

The award specifically recognizes the exceptional service provided to Lake Mohawk, the New Jersey Coalition of Lake Associations (NJCOLA) and the Lake Mohawk Preservation Foundation (LMPF). The nomination for the award was submitted by Barbara Wortmann, Interim GM of the LMCC, Ernest Hofer PE, Science Advisor to LMPF and Board President of NJCOLA, and the full Board of Trustees of NJCOLA.

As the article states, Steve and the Princeton Hydro team have worked to develop and implement successful lake management strategies to restore and protect the health of the lake and its surrounding watershed. Lake Mohawk is now a role model for all of New Jersey’s lakes.

While accepting his award Dr. Souza stated, “this would not have been possible had it not been for the foresight of the Lake Mohawk Country Club and the support we have received over the years from the Lake Board, the current General Manager Barbara Wortmann, Steve Waehler and the Lake Committee, Ernie Hofer and Gene DePerz of the Lake Mohawk Preservation Foundation, and of course the late Fran Smith.” Steve went on to thank his staff at Princeton Hydro, especially Chris Mikolajczyk, CLM and Dr. Fred Lubnow, for their efforts over the years.

More About Lake Mohawk Lake Restoration:

Nutrient pollution is one of the main problems affecting lakes throughout the United States. In small amounts, nitrates and phosphates can be beneficial to many ecosystems. However, in excessive amounts, nutrients cause eutrophication. Eutrophication stimulates an explosive growth of algae (algal blooms) that depletes the water of oxygen and cause serious water quality issues. Lake Mohawk was suffering from eutrophication issues.

In the early 1990’s, Princeton Hydro was contracted by the LMCC to conduct a detailed water quality and trophic state assessment of the lake. The data was used to prepare a comprehensive lake management master plan.

A unique element of the plan was the design and installation of a “one-of-a-kind” continual, dosing alum pumping system, which reduced and controlled the lake’s sizable internal total phosphorus load and the phosphorus originating from stormwater and other external sources. This innovative nutrient control program was the first of its kind in New Jersey, and, to this day, remains in operation and is the foundation of the lake’s restoration. Following suit from Lake Mohawk’s success, a similar system was also designed and installed in White Meadow Lake and that system is also largely responsible for its restoration.

The success of this program was recognized by the USEPA through an Environmental Excellence Award, by the NJDEP through an Environmental Initiative Award, by the NALMS through a Technical Merit Award, and now by NALMS with the 2017 Lake Management Success Stories Award.

Read more about the accomplishments at Lake Mohawk in the LMCC’s recent Papoose newsletter.




New Jersey, like other coastal states, has been losing coastal wetland habitats to a combination of subsidence, erosion and sea level rise. The New Jersey Department of Environmental Protection received a grant from the National Fish and Wildlife Federation to address this issue and rejuvenate these critical habitats. Grantees were charged with providing increased resilience to natural infrastructure that will in turn increase the resiliency of coastal communities in the face of future storms like Hurricane Sandy.

As a consultant for GreenTrust Alliance, a land conservancy holding company, Princeton Hydro worked with several project partners, including NJDEP, the US Army Corps of Engineers, NJDOT, The Wetlands Institute, and The Nature Conservancy, to increase the marsh elevation to an optimal range where vegetation, and the wildlife that depends on it, can flourish. One of the techniques used for this project included the use of dredged material disposal placement, which involves using recycled sand and salt dredged from navigation channels to boost the elevation of the degraded marsh.

A media statement from NJDEP further explained the process, “sediments dredged from navigation channels and other areas are pumped onto eroding wetlands to raise their elevations enough to allow native marsh grasses to flourish or to create nesting habitats needed by some rare wildlife species. Healthy marshes with thick mats of native grasses can cushion the impact of storm surges, thereby reducing property damage.”


The salt marsh at the Fortescue project site is part of the Fortescue Wildlife Management Area. The specific goal of the project was to restore and enhance the interior high and low marsh, coastal dune and beach habitats.

To achieve these habitat enhancements, the Princeton Hydro project team first established biological benchmarks of each targeted habitat type and evaluated them to determine the upper and lower elevational tolerances for target communities and plant species. Approximately 33,300 cubic yards of dredged materials were used to restore a degraded salt marsh, restore an eroded dune, and replenish Fortescue Beach. The eroded dune was replaced with a dune designed to meet target flood elevations and protect the marsh behind it against future damage. The dune was constructed using dredged sand, and, to prevent sediment from entering the waterways, a Filtrexx containment material was used.


This project site is a tidal marsh complex located within a back-bay estuary proximal to Stone Harbor and Avalon. Princeton Hydro and project partners aimed to enhance the marsh in order to achieve the primary goal of restoring the natural function of the tidal marsh complex.

Two main activities were conducted in order to apply the dredged material to the impaired marsh plain: 1.) the placement of a thin layer of material over targeted areas of existing salt marsh to increase marsh elevations, 2.) the concentrated placement of material to fill expanding pools by elevating the substrate to the same elevation as the adjacent marsh. In total, dredged material was distributed among eight distinct placement areas throughout the property’s 51.2 acres.

These coastal wetland restoration activities will help to prevent the subsidence-based marsh loss by filling isolated pockets of open water and increasing marsh platform elevation. In addition, the beneficial reuse of dredged material facilitates routine and post-storm dredging and improves the navigability of waterways throughout the U.S.


Welcome to the second installment of Princeton Hydro’s multi-part blog series about aquatic organism passage.

What you’ll learn:

  • How does promoting aquatic organism passage benefit ecosystems as a whole?
  • How can others, including people, benefit from aquatic organism passage?
  • How has Princeton Hydro supported it?

Photo by Princeton Hydro Founder Steve Souza

Fostering Ecological Balance in Food Webs

A major consequence of poorly designed culverts published in the NRCS' "Federal Stream Corridor Restoration Handbook"is the destabilization of food webs. Sufficient predators and prey must exist to maintain a balanced food web. For example, freshwater mussels (Unionidae) are a common snack among fish. A mussel’s life cycle involves using certain fish as a host for their larvae until these microscopic juveniles mature into their adult forms and drop off. During this period, the host fish will travel, effectively transporting a future food source with it.

In the presence of habitat fragmentation, the isolation of these symbiotic relationships can be devastating. Some mussel species rely on a small circle of fish species as their hosts, and conversely, some fish species rely on specific mussel species as their food. If a fish species is separated from its mussel partner, food shortages owing to a declining adult mussel population can occur.

Widespread Benefits to Flora, Fauna, and People

A shift in the 1980s recognized the importance of redesigning road-stream crossings for several reasons, including restoring aquatic organism passage and maintaining flood resiliency. Replacing culverts with larger structures that better facilitate the movement of both water and aquatic organisms benefit all species. Roads constructed over streams allow people to travel across natural landscapes while culverts that are fish-friendly convey water at a rate similar to the surrounding landscape, reducing scour in stream beds.

A man fly fishes as his dog sits by his side at Ken Lockwood Gorge, Hunterdon County. Photo from State of New Jersey website.

Fish, as well as semi-terrestrial organisms like crabs and salamanders, can take advantage of more natural stream environments and complete their migrations. Anglers appreciate healthy, plentiful fish populations nearly as much as the fish themselves. Recreation and economic growth also improve when streams regain the aquatic biological communities once lost through habitat fragmentation. According to USFWS, for every dollar spent on restoration through the Partners for Fish and Wildlife Program and Coastal Program Restoration Project, states gain $1.90 of economic activity. Stream restoration improves fish and wildlife habitat, which directly supports and enhances recreation opportunities for outdoor enthusiasts thus resulting in increased tourism-related spending and job growth.

Aquatic Organism Passage in Action at Princeton Hydro

Princeton Hydro recently completed a project to facilitate aquatic organism passage for river herring in Red Brook in Plymouth, Massachusetts. Read all about it here!

For an introduction to aquatic organism passage, be sure to check out the first post in this multipart-series.


“Aquatic Organism Passage through Bridges and Culverts.” Flow. Vermont Department of Environmental Conservation’s Watershed Management Division, 31 Jan. 2014. Web. 14 Mar. 2017.

Hoffman, R.L., Dunham, J.B., and Hansen, B.P., eds., 2012, Aquatic organism passage at road-stream crossings— Synthesis and guidelines for effectiveness monitoring: U.S. Geological Survey Open-File Report 2012-1090, 64 p.

Jackson, S., 2003. “Design and Construction of Aquatic Organism Passage at Road-Stream Crossings: Ecological Considerations in the Design of River and Stream Crossings.” 20-29 International Conference of Ecology and Transportation, Lake Placid, New York.

Kilgore, Roger T., Bergendahl, Bart S., and Hotchkiss, Rollin H. Publication No. FHWAHIF-11-008 HEC-26. Culvert Design for Aquatic Organism Passage Hydraulic Engineering Circular Number 26. October 2010.

Michigan Natural Features Inventory. Freshwater Mussels of Michigan. Michigan State University, 2005.


Employee Spotlight: Meet Our New Team Members

Princeton Hydro is thrilled to announce the expansion of our growing business with the addition of 10 team members who possess a wealth of experience and qualifications in a variety of fields related to water resource management.

“The addition of these professionals is attributable to the successful teaming relationships we have developed and grown with our clients, and is our commitment to investing in meeting their respective missions,” said Princeton Hydro President Geoff Goll.  “We’re proud have such talented experts in their fields join our team, who also share our ideals of creativity, ingenuity, quality, and teamwork.”


Meet Our New Team Members:


Emily Bjorhus, Environmental Scientist

Emily is an Environmental Scientist with expertise in environmental permitting and compliance, wetland and stream ecology, and stormwater management. She coordinates, leads and assists with state environmental permitting programs and NEPA compliance and documentation, including preparation of Federal and state permit applications, Endangered Species Act 7 consultations, and Federal Energy Regulatory Commission environmental review processes. She also conducts a variety of environmental field investigations such as wetland and waterbody delineations.  Read more.


Stephen Duda, EIT, Project Engineer

Stephen is a civil engineer with expertise in grading and stormwater design, drafting, permitting, soil testing and construction inspection.  He has experience working on multiple aspects of land development projects, construction management and  municipal engineering.  He holds an an Associate degree in General Engineering and a second in Engineering Technologies/CAD, as well as a B.S. in Civil Engineering from Rowan University. Read more. 



Shaun Flite, EIT, Civil Engineer

Shaun is a Civil Engineer who has provided over 5 years of consulting services to assist with planning, design, and permitting of projects involving land development, stormwater management, water & wastewater utility systems, and pollution control. He is a graduate of Penn State where he earned his Bachelor of Science in Environmental Engineering, with an emphasis in hydrology, hydraulics, and water quality/treatment. Read more.



George Fowler, PE,  Water Resource Engineer

George is a Water Resource Engineer with an expertise in natural system’s features and functions, river engineering designs and geomorphic investigations.  Well versed in U.S. Army Corps of Engineers and NRCS engineering manuals, he seeks to work with people who desire river engineering solutions that follow sound engineering practices, improve the aquatic environment and have low to no maintenance costs.  His designs have ranged from traditional flood protection features (earthen berms and dams) to fish habitat enhancement (engineered log jams and roughened log stream bank toes).  Read more.


Casey Hurt, PE, Geotechnical Project Manager

Casey is a licensed Professional Engineer with over 6 years of experience working in Geotechnical Engineering. He maintains a wide range of professional responsibilities for the firm including subsurface explorations, development of geotechnical laboratory testing programs, shallow and deep foundation analysis and design, settlement evaluation, earth retaining system design, slope stability analyses, and management of geotechnical field operations. He has extensive experience with stormwater infiltration and dam safety compliance. Read more.


Elizabeth Kowalsky, Assistant Coordinator

Liz earned her B.A. in Communications with a concentration in Public Relations from Stockton University. She has a background in working with public relations firms in the areas of technology, pharmaceuticals, outdoor products/safety and family wellness. Read more.




Dana Patterson, Communications Strategist

Dana is a passionate environmental communicator who brings a strong mix of diverse stakeholder engagement experience, coupled with values-based communication strategy. She specializes branding, marketing, and digital media strategy, and strives to enhance the mission and values of Princeton Hydro. She earned her Master of Environmental Management from Yale University’s School of Forestry and Environmental Studies where she focused on strategies for climate change and wildlife conservation communication.  Read more.



Natalie Rodrigues, EIT, CPESC-IT, Staff Engineer

Natalie is a staff engineer with a focus in water resources engineering. She assists with various projects that span several topics, including stormwater management, ecosystem restoration, and dam safety. Natalie is a recent graduate from SUNY College of Environmental Science and Forestry where she earned her Bachelor of Science in Environmental Resources Engineering with a focus in water resources.  Read more.



Jack Szczepanski, PhD, Senior Aquatics Scientist

Jack has a range of experience from establishing baseline assessment for fish populations to managing coastal wetland resilience projects to developing ecosystem-wide monitoring plans. Jack earned his PhD from URI by studying fish feeding ecology and trophic dynamics across marine ecosystems. He also has academic background in biomechanics, wetland and estuarine ecology, and natural resource applications of conservation biology.  Read more.



Thomas Wilkes, PE, Senior Project Manager

Tom is a Professional Civil Engineer specializing in municipal, civil, and environmental engineering consulting services primarily in Pennsylvania and Delaware. He is an accomplished and multi-talented Municipal Engineer with more than 10 years of significant experience in planning, scheduling, managing and administration of public works projects, and providing maintenance support for municipal utility systems (stormwater, sanitary, sewer, and water). Read more.




Stay tuned for more!

Improving Water Quality & Reducing Habitat Loss with Floating Wetland Islands

Floating Wetland Islands (FWI), also known as floating treatment wetlands, are an effective alternative to large, watershed-based, natural wetlands. Often described as self-sustaining, FWIs provide numerous ecological benefits. They assimilate and remove excess nutrients that could fuel algae growth; provide habitat for fish and other aquatic organisms; help mitigate wave and wind erosion impacts; provide an aesthetic element; and can be part of a holistic lake/pond management strategy. FWIs are also highly adaptable and can be sized, configured and planted to fit the needs of nearly any lakepond or reservoir.

Princeton Hydro Senior Scientist Katie Walston recently completed the Floating Island International (FII) Floating Wetland Master Seminar. The seminar provided participants with an in-depth look at the various technologies and products FII offers. Through hands-on examples, course participants learned how to utilize wetland islands for fisheries enhancement, stormwater management, shoreline preservation, wastewater treatment and more.

“The Master Seminar was truly valuable both personally and professionally,” said Katie. “I learned a tremendous amount and thoroughly enjoyed the experience. It’s very fulfilling knowing that I can take the knowledge I’ve learned back to Princeton Hydro and make positive impacts for our clients.”

FII was launched by inventor and outdoorsman Bruce Kania who was driven by the desire to reverse the decline of wetland habitats by developing a new and natural stewardship tool that could clean water and, in the process, improve life for all living creatures. He found that the answer lies in Biomimicry: duplicating nature’s processes in a sustainable, efficient and powerful way to achieve impeccable environmental stewardship for the benefit of all life.

Bruce brought together a team of engineers and plant specialists and created BioHaven® floating islands. These islands biomimic natural floating islands to create a “concentrated” wetland effect. Independent laboratory tests show removal rates far in excess of previously published data: 20 times more nitrate, 10 times more phosphate and 11 times more ammonia, using unplanted islands. They are also extremely effective at reducing total suspended solids and dissolved organic carbon in waterways.

Due to population growth, industrialization and climate change, wetlands are at risk of rapidly declining in quantity and quality due. However, every floating wetland island launched by FII provides an effective strategy for mitigating and adapting to the impacts of over development and climate change.

The unique design of BioHaven® floating islands means that 250 square feet of island translates to an acre’s worth of wetland surface area. These versatile floating islands can be launched in either shallow or deep water, and can be securely anchored or tethered to ensure that they remain in a specific location. They are almost infinitely customizable, and can be configured in a variety of ways.

In addition to ongoing prototype development, FII offers licensing opportunities to businesses and production facilities worldwide. FII continues to research and develop collaborative pilot projects to quantify BioHaven® floating islands’ efficacy.

Many thanks to Bruce and Anne Kania for hosting the Floating Wetland Master Seminar and inspiring action through their knowledge, passion and ongoing endeavors.


Princeton Hydro Founder Invited to Speak at EPA’s Harmful Algal Blooms Workshop

Princeton Hydro Founder Dr. Steve Souza was an invited speaker at the USEPA Region 2 Freshwater Harmful Algal Blooms (HABs) and Public Drinking Water Systems workshop last week in Manhattan. The objective of the workshop was to share information about the monitoring and assessment of freshwater HABs and the efforts to minimize their effect on public drinking water and the recreational uses of lakes.

Steve’s presentation focused on the proactive management of HABs, providing useful tips for and real-world examples of how to address HABs before they manifest, and, if a HAB does manifest, how to prevent it from further exacerbating water quality and cyanotoxin problems.

The workshop was well attended with 80 people on site and 40 others participating via webinar link. Steve was joined by nine other invited speakers, most of whom were representing the USEPA, NYSDEC and NJDEP, who gave presentations on a variety of HABs related topics, including the optimization of water treatment operations to minimize cyanotoxin risks surveillance and assessment of HABs, and communicating HABs risks in recreational lakes and drinking water reservoirs.

If you’re interested in learning more about HABs, you can view a complete copy of Steve’s presentation, titled Proactive Management of Harmful Algae Blooms in Drinking Water and Recreational Waterbodies, by clicking the image below. Please contact us anytime to discuss how Princeton Hydro’s Invasive Weed and Algae Management Services can be of service to you.

The USEPA Region 2 serves New Jersey, New York, Puerto Rico, the U.S. Virgin Islands, and eight tribal nations. Get more info on key issues and initiatives in USEPA Region 2.



Princeton Hydro Dam Removal Work Featured at Brazilian Workshop

As Brazil is in the midst of a dam-building boom, scientists and engineers gathered at a workshop in Brazil to discuss, “Dam Removal & Optimizing Hydro Locations to Benefit Species Diversity in Brazil.”

Laura Wildman, P.E., Water Resources and Fisheries Engineer and Director of Princeton Hydro’s New England Regional Office, was invited to speak at the workshop. Her presentation focused on why we remove dams in the U.S. (the key drivers), how we analyze them for removal, and what we are learning through a wide diversity of completed case studies.

“It was fascinating to discuss a topic, such as the removal of dams, right as Brazil is focusing on building more hydro capacity,” said Laura. “Hopefully it is a sign that the hydro industry in Brazil, along with all the great Brazilian fisheries researchers, are quite forward thinking and are determined to maintain their country’s rich species diversity while also enhancing their energy options.”

The workshop, hosted by CEMIG and held at UFMG, involved many universities, including our workshop host Paulo Pompeu from UFLA, Dr. Paul Kemp from University of Southhampton, Dr. Jesse O’Hanley of Kent Business School, and many others.

The gathering inspired a lot of interesting dialogue around dam removal, optimizing locations for new hydro facilities, and how to best sustain connectivity and species diversity. Laura’s presentation entitled “Dam removal in the United States” along with the other conference presentations will be available on the CEMIG website soon or check back here on the Princeton Hydro blog for presentation links.

Aquatic Organism Passage: A Princeton Hydro Blog Series

Introducing part one of a multi-part blog series about aquatic organism passage
What you’ll learn:
  • What is aquatic organism passage?
  • Why is it important?
  • How does Princeton Hydro support it?

This photo from NYS DEC demonstrates a well-designed stream crossing.

Since the US government began allotting funds for building roads in U.S. national forests in the late 1920s, hundreds of thousands of culverts were built across the country. Culverts, or drainage structures that convey water underneath a barrier such as a road or railroad, were originally built with the intention of moving water quickly and efficiently. While this goal was met, many migratory fish and other aquatic organisms could not overcome the culverts’ high-velocity flows, sending them away from their migratory destinations. If the culvert was perched, or elevated above the water surface, it would require the migratory aquatic animals to both leap upwards and fight the unnaturally fast stream current to continue their journeys. Additionally, turbulence, low flows, and debris challenged the movement of aquatic organisms.

Thus, the goal of aquatic organism passage (AOP) is to maintain connectivity by allowing aquatic organisms to migrate upstream or downstream under roads. AOP “has a profound influence on the movement, distribution and abundance of populations of aquatic species in rivers and streams”. These aforementioned species include “fish, aquatic reptiles and amphibians, and the insects that live in the stream bed and are the food source for fish”.

This photo from NYS DEC demonstrates a poorly-designed stream crossing.

A poorly designed culvert can harm fish populations in multiple ways. If sturgeon aren’t able to surpass it, habitat fragmentation prevails. And so, a once-connected habitat for thousands of sturgeon breaks into isolated areas where a few hundred now live. When the population was in the thousands, a disease that wiped out 80% of the population would still leave a viable number of individuals left to survive and mate; a population of a few hundred will be severely hurt by such an event. In sum, habitat fragmentation raises the risk of local extinction (extirpation) as well as extinction in general.

The splintering of a large population into several smaller ones can also leave species more vulnerable to invasive species. Generally, the greater the biodiversity harbored in a population, the stronger its response will be against a disturbance. A dwindling community of a few hundred herring will likely succumb to an invasive who preys on it while a larger, more robust community of a few thousand herring has a greater chance of containing some individuals who can outcompete the invasive.

Aquatic Organism Passage in Action at Princeton Hydro

Princeton Hydro recently teamed up with Trout Unlimited to reconnect streams within a prized central-Pennsylvanian trout fishery.  Our team enabled aquatic organism passage by replacing two culverts in Pennsylvania’s Cross Fork Creek. Read about it here!


“Aquatic Organism Passage through Bridges and Culverts.” Flow. Vermont Department of Environmental Conservation’s Watershed Management Division, 31 Jan. 2014. Web. 14 Mar. 2017.

Hoffman, R.L., Dunham, J.B., and Hansen, B.P., eds., 2012, Aquatic organism passage at road-stream crossings— Synthesis and guidelines for effectiveness monitoring: US Geological Survey Open-File Report 2012-1090, 64p.

Jackson, S., 2003. “Design and Construction of Aquatic Organism Passage at Road-Stream Crossings: Ecological Considerations in the Design of River and Stream Crossings.” 20-29 International Conference of Ecology and Transportation, Lake Placid, New York.

Kilgore, Roger T., Bergendahl, Bart S., and Hotchkiss, Rollin H. Publication No. FHWAHIF-11-008 HEC-26. Culvert Design for Aquatic Organism Passage Hydraulic Engineering Circular Number 26. October 2010.