New Book Aims to Protect and Restore Fish Migrations

Rivers are a critical natural resource and an essential element for the health and survival of billions of people and countless species. Flourishing populations of migratory fish are an important indicator of a healthy, coastally connected river and a robust aquatic ecosystem as a whole. Migratory fish help to maintain a balanced food web, support productive river systems, and provide income for people around the world.

Yet many migratory fish species are severely threatened primarily due to man-made obstacles like dams and weirs, which disrupt the natural flow of rivers and prevent fish migration. When fish can’t reach their habitat, they can’t reproduce and maintain their populations.

Photo Credit: “From Sea to Source 2.0”

A new book, titled From Sea to Source 2.0, explores the challenges that lie behind restoration of fish migration in rivers around the world and provides a practical guide to promoting the protection and restoration of fish migration. The book is a unique collaboration of over 100 international fisheries professionals and supported by river managers, governments, research institutes and NGOs including World Wildlife Fund and The Nature Conservancy. Geared toward practitioners, but also a wonderful resource for the general public, the book is comprised of inspiring stories from nearly every continent on the planet. Click here to download it for free.

“Ultimately our ambition is to contribute in a positive way to making a better world and a positive difference for migratory fish, nature and humans on local and global levels by inspiring new initiatives for and with people all around the world,” as stated on www.fromseatosource.com. “Whether the challenge is simply to increase access to spawning habitats through connectivity improvements for salmon, or to maintain the livelihoods for hundreds of millions of people dependent upon fish and fisheries in the great rivers of Asia, Africa and South America, we hoped our book would help to achieve these goals.”

Princeton Hydro’s Dam Removal Expert Laura Wildman, P.E. and Fluvial Geomorphologist Paul Woodworth are proud contributors to the book, helping to write the dam removal chapter, creating a dam removal flow chart for the book, and providing multiple photos utilized in the book. Princeton Hydro is also listed as a contributing sponsor.

“We’re so proud to be part of this incredible project with so many partners globally,” said Wildman. “We envision that this book will provide a valuable resource and inspiration for those in countries and regions where the importance of restoring riverine connectivity is newly gaining momentum. We hope it will help emphasize the importance of finding balanced and environmentally informed solutions when proposing additional utilization of public trust resources such as rivers.”

Approximately 40% of all fish species in the world reside in freshwater ecosystems, contributing economic and ecological benefits and value. It’s critical that we support efforts that aim to protect migratory fish species, reconnect rivers, sustain fish passage, and preserve free-flowing rivers through removing unnecessary dams, reconnecting floodplains, managing our water use, and managing hydropower for sustainable rivers.

Education and awareness building are key first steps in protecting rivers. From Sea to Source 2.0 seeks to inform, educate and inspire those who want to know more about how to meet the challenges of restoring fish migration in rivers around the world.  The book is regarded as a crucial resource in the ongoing fight to protect and preserve the enormous value of our waterways.

Get your free copy here.

Princeton Hydro has designed, permitted, and overseen the reconstruction, repair, and removal of a dozens of small and large dams in the Northeast. To learn more about our fish passage and dam removal engineering services, visit: bit.ly/DamBarrier.

Conservation Spotlight: Restoring Fish Passage on the Noroton River

For thousands of years, river herring swam from the Atlantic Ocean through the Long Island Sound and up the Noroton River to spawn each spring. Then, they returned to the ocean until the next spawning season.

Back in the 1920s, President Dwight D. Eisenhower’s administration began connecting the country through a massive interstate highway system. As part of the infrastructure plan, hundreds of thousands of culverts were built across the U.S. with the intention of moving water quickly and efficiently. While that goal was met, many migratory fish and other aquatic organisms could not overcome the culverts’ high-velocity flows, shallow water depths, and perched outlets. This infrastructure prevented them from reaching their native migratory destinations.

By the late 1950s, Interstate 95 cut through Connecticut’s coastal rivers, and culverts were installed to convey river flows. Alewives, American Shad, Blueback Herring, and other native fish species were unable to navigate the culverts. Their populations dwindled to the point where Connecticut, along with Rhode Island, Massachusetts, and North Carolina, instituted moratoriums on catching and keeping the valued forage fish.

Along the Noroton River, three parallel concrete culverts, each 300-feet long, 13-feet wide and 7-feet in height were installed, completely blocking upstream fish passage.  In order to restore important fish populations and revitalize the Noroton River, Save the Sound launched a project that reopened approximately seven miles of the river, allowing migratory fish populations to safely and easily travel through the culverts to reach their original spawning habitat upstream.

The project is a collaboration among Save the Sound, Darien Land Trust, Connecticut Department of Energy and Environmental Protection (CTDEEP), Connecticut Department of Transportation, Princeton Hydro, and other partners. For the project, Princeton Hydro lead design engineering and guided the construction of the following elements to restore upstream fish passage:

  • The installation of a concrete weir at the upstream end of the culvert to increase water depths in one culvert during low-flow periods;
  • The installation of concrete baffles to reduce flow velocities and create resting places for fish, and;
  • The installation of a naturalized, step-pool, rock ramp at the downstream end of the project to allow fish to ascend into the culvert gradually, overcoming the two-foot vertical drop present under existing conditions. The rock ramp consists of a grouted riverstone base with large grouted boulders arranged to make steps, with low-flow passage channels, between a series of pools approximately 1-foot deep that create resting places for upstream migrating fish.

Reopening river passage for migratory species will improve not only the health of the Noroton River itself, but will also benefit the overall ecosystem of Long Island Sound. Over the last decade, fish passage projects around the sound’s Connecticut and New York shores have dramatically increased freshwater spawning habitat for the foundational species whose return is restoring a more vibrant food web to the Long Island Sound.

Construction of the baffles and rock ramp were completed in time for the 2018 migratory season. Construction of the concrete weir is on temporary hold for low-flow conditions. On April 26, 2018, project partners gathered for a project celebration and the release of migratory fish by CTDEEP at an upstream location.

“It’s fascinating to feel the change in the flow patterns against your legs as you walk through the baffled culvert knowing that it will now facilitate fish passage through this restored reach,” said Princeton Hydro’s New England Regional Office Director and Water Resources and Fisheries Engineer Laura Wildman, P.E. “It is a very attractive and natural-looking fishway, and we’re proud to have created a design that fits so well into the surrounding landscape.”

Princeton Hydro has designed, permitted, and overseen the reconstruction, repair, and removal of a dozens of small and large dams in the Northeast.  To learn more about our fish passage and dam removal engineering services, visit: bit.ly/DamBarrier.

New Video Celebrates 50th Anniversary of Wild & Scenic Rivers Act

Credit: NPS.gov

Communities across the nation are preparing to celebrate the 50th anniversary of the Wild and Scenic Rivers Act. This landmark legislation passed by Congress in October 1968 safeguards the free-flowing character of rivers by precluding them from being dammed, while allowing the public to enjoy them. It encourages river management and promotes public participation in protecting streams.

As part of the celebration, the National Park Service released a new video highlighting a handful of ‘Wild and Scenic’ designated rivers in the Northeast – the Farmington, Sudbury, Assabet, Concord, and Musconetcong Rivers – along with the organizations and community volunteers who work together to protect and care for these rivers.

Princeton Hydro is proud to work with two of the river stewards featured in the video: Musconetcong Watershed Association (MWA) and Farmington River Watershed Association (FRWA).

The Musconetcong River:

Designated ‘Wild and Scenic’ in 2006, the Musconetcong River is a 45.7-mile-long tributary of the Delaware River in northwestern New Jersey.

Princeton Hydro has been working with MWA in the areas of river restoration, dam removal, and engineering consulting since 2003 when the efforts to remove the Gruendyke Mill Dam in Hackettstown, NJ began. To date, Princeton Hydro has worked with MWA to remove five dams on the Musconetcong River, the most recent being the Hughesville Dam.

As noted in the video, the removal of these dams, especially the Hughesville dam, was a major milestone in restoring migratory fish passage along the Musconetcong. Only a year after the completion of the dam removal, American shad returned to the “Musky” for the first time in 250 years.

“The direction the river is moving bodes well for its recovery,” said Princeton Hydro President Geoff Goll, P.E., who was interviewed in the 50th anniversary video. “This multidisciplinary approach using ecology and engineering, paired with a dynamic stakeholder partnership, lead to a successful river restoration, where native fish populations returned within a year. ”

The Farmington River:

The Upper Farmington River, designated as ‘Wild and Scenic’ in 1994, stretches 14-miles through Connecticut starting above Riverton through the New Hardford/Canton town line. The river is important for outdoor recreation and provides critical habitat for countless wildlife.

Credit: FWRA.orgBack in 2012, Princeton Hydro worked with the FRWA and its project partners to remove the Spoonville Dam. Built in 1899 on the site of a natural 25-foot drop in the riverbed, the dam was originally a hydropower facility. The hurricanes and flood of 1955 breached the dam, opening a 45-foot gap and scattering massive dam fragments in the riverbed downstream. The remnant of the main dam persisted for decades as a 128-foot long, 25-foot high obstacle in the channel. The river poured through the breach in a steep chute that stopped American shad from proceeding further upstream to spawn.

The project was completed, from initial site investigation through engineering assessment and final design, in just six months. The dam removal helped to restore historic fish migrations in the Farmington River (including the American shad) and increase recreation opportunities.

Wild & Scenic Rivers Act:

Credit: NPS.govAs of December 2014 (the last designation), the National ‘Wild and Scenic’ System protects 12,734 miles of 208 rivers in 40 states and the Commonwealth of Puerto Rico; this is a little more than one-quarter of 1% of the nation’s rivers. By comparison, more than 75,000 large dams across the country have modified at least 600,000 miles, or about 17%, of American rivers.

In honor of the 50th anniversary of the Act and in an effort to designate many more miles of river as ‘Wild and Scenic,’ four federal agencies and four nonprofit groups are coordinating nationwide events and outreach. Managing agencies are the Bureau of Land ManagementFish and Wildlife ServiceForest Service, and National Park Service, along with American RiversAmerican WhitewaterRiver Network and River Management Society. Go here for more info: www.wildandscenicrivers50.us.

AQUATIC ORGANISM PASSAGE: A PRINCETON HYDRO BLOG SERIES

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.

Sources:

“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.

 

Musconetcong Watershed Association Presents Princeton Hydro President with Prestigious “Friend of the River” Award

 

Musconetcong Watershed Association (MWA) held a dinner to celebrate its 25th anniversary as well as the 150th anniversary of the Asbury Grist Mill, which the MWA is working to restore. The evening included a cocktail hour, a buffet dinner, silent auction, remarks by the MWA President Tish Lascelle and Executive Director Alan Hunt, and a presentation of awards.

The MWA presented Princeton Hydro PresiPhoto by Tish Lascelle, President, Musconetcong Watershed Associationdent Geoff Goll, PE with the “Friend of the River” Award. This award, which has only been given seven times in MWA’s 25 years of service, recognizes individuals who have made a significant and sustainable difference in the Watershed and helped to advance its mission. Recipients of the Award have also demonstrated outstanding leadership through their volunteer efforts or partnerships with MWA.

Geoff was honored to receive the award alongside Paul Kenney of the National Park Service and Richard C. Cotton, a Managing Partner of the Hawk Pointe Golf Club and Asbury Farms Real Estate. Paul was assigned the Musconetcong River in late 2003 and was instrumental in obtaining the Musconetcong River’s Wild and Scenic Designation in 2006. He has continued to be an excellent resource of the National Park Service.  Richard is a founding member of the MWA’s Board of Trustee’s and continues to serve on the Board. He has dedicated his professional life to striking a balance between economic growth with environmental protection.

Geoff has been working with MWA in the areas of river restoration, dam removal, and engineering consulting since 2003, when the efforts to remove the Gruendyke Mill Dam in Hackettstown, NJ began. He has since worked with the Princeton Hydro team to remove five dams on the Musconetcong River, the most recent being the Hughesville Dam

MWA is an independent, non-profit organization dedicated to protecting and improving the quality of the Musconetcong River and its Watershed, including its natural and cultural resources. Members of the organization are part of a network of individuals, families and companies that care about the Musconetcong River and its watershed, and are dedicated to improving the watershed resources through public education and awareness programs, river water quality monitoring, promotion of sustainable land management practices and community involvement.

During the anniversary dinner, participants also got a sneak peek of a new video from the National Park Service that is set for public release in 2018. The video celebrates the upcoming 50th anniversary of the Federal Wild and Scenic Rivers Act, under which the Musconetcong River is protected, and explores the importance of free-flowing rivers and why Americans treasure them. Representing Princeton Hydro at the awards dinner were Vice President Mark Gallagher, his wife Jennifer, Geoff and his wife Amy, and Director of Engineering Services Mary Paist-Goldman, PE.

 

 

 

 

 

 

 

 

 

 

 

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!

Sources:

“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.

The Restoration of Bound Brook

To the delight of fish and environmentalists alike, an important step has been made in the removal of the aging spillway of Hunters Pond Dam in Scituate and Cohasset, Massachusetts. The spillway was notched to ensure a gradual release of water from the impoundment, letting Bound Brook flow free again after being dammed for centuries.

As the first barrier upstream from the Atlantic Ocean, the dam’s removal restores 5-miles of river spawning ground and habitat for alewife, blueback herring, American eel, rainbow smelt, sea lamprey and other important species. The removal of Hunters Pond Dam also reduces the threat of dam failure.

Princeton Hydro is proud to be working on this project with T Ford Company, U.S. Fish and Wildlife Service, and many other great partners. The project is funded by grants from the Massachusetts Department of Ecological Restoration and the NOAA.

The project also includes rebuilding a culvert, removing a concrete spillway, and replacing a water main. Stay tuned for more!

Habitat Fragmentation – Culvert Blockages and Solutions

Capture

Culvert that is “perched” due to scour by high velocity flows through the pipe. ©Princeton Hydro.

The Bucks County Chapter of Trout Unlimited (Pennsylvania) and the Cooks Creek Watershed Association were featured in the Summer 2013 edition of Trout magazine, TU’s national publication, for their culvert inventory work in the Cooks Creek watershed.  Princeton Hydro was glad to assist via directly investigating and training of volunteers to inspect and document potential culverts in need of retrofit.  Princeton Hydro also completed design concepts and opinion of costs for two example culverts.  Identified culverts in need of retrofit will help the creek’s wild brown and brook trout.  Princeton Hydro based the training on the Vermont guidelines for rating culverts for pass-ability.  In this small watershed a total of 97 culverts were identified with 32 of them as potential barriers, and 11 identified as “high priority” in need of retrofit.

Why worry about culverts, you say?

One of the most unforeseen danger to the biodiversity in our river networks is habitat fragmentation through un-passable culverts throughout the United States.  While blockages via dams number upward of 100,000 or so, the blockages created by ecologically and biologically inefficient culverts is likely to number in the millions.   The majority of these culverts are located in headwater areas of rivers, which entail greater than 50% of most river miles in a watershed; a large cumulative impact.  As a result, native key headwater species such as brook trout (Salvelinus fontinalis) in the East and cutthroat trout (Oncorhynchus clarkii) in the West have had their historic ranges reduced to a fraction of their former extent.

Historically, culverts were designed by civil engineers to maximize flow capacity and minimize pipe size in order to create the most economical structure for developers, transportation authorities, and municipalities.  The unfortunate by-product of such a design approach is that water velocity through culverts is extremely high, often running in supercritical flow, even during base flow conditions, and the smooth and featureless surfaces in the structure make it extremely difficult to navigate.  To add insult to injury, the high velocity flows also scour and erode the stream channel immediately downstream of the culvert, leaving the pipe too high out of the new channel (“perched pipes”) for organisms to pass.  Downstream water dependent organisms cannot pass upstream to new habitat, and those populations upstream become extirpated due to downstream migration and mortality, and the lack of an ability to return or be replaced.  A study of impacts of fragmentation on brook trout is ongoing by the USGS Conte Anadromous Fish Research Center (USGS CAFRC) and others, and a study recently completed documented the impacts of fragmentation of local populations provides an informative view of the blockage potential of culverted streams.

There is hope in the re-connection of stream habitat through new research and initiatives developed since 1999.  One such approach is through the Stream Simulation design originally developed in its present form at the Washington State Department of Fish & Wildlife and adopted by the US Forest Service, US Fish and Wildlife Service, as well as others, and was also adopted shortly thereafter and refined by the University of Massachusetts, Amherst Extension (Stream Continuity model) for use in Northeastern States (initially in the Massachusetts River and Stream Crossing Standards, and then adopted in similar form by surrounding states).  Through the Stream Simulation/Continuity method, a culvert is not simply measured in terms of hydraulic efficiency, but also in terms of ecological and biological efficiency.

In the most basic terms, Stream Simulation (Continuity) requires a crossing that has a minimum width of the bankfull flow of the natural channel upstream and downstream, plus more width to allow passage of terrestrial organism passage such as reptiles and amphibians (in the UMASS model the increase in width is 20% wider than bankfull, but in the current Washington State model they use 20% plus 2 feet).  The other part of the design requirement is an opening area to length ratio to allow the maximum amount of natural light penetration into the culvert (openess ratio), as many organisms, such as fish, are too intimidated to travel through dark culverts.  Other design requirements include the use of slopes and velocities that allow for fish passage, and roughness (i.e. placement of natural substrate) to also slow down the flow.

The key challenge for the retrofitting of culverts to be more passable is cost.  As with any civil engineering project, the larger it is, the more expensive.  To replace a 36 inch diameter culvert with a 10-14 foot wide structure could increase the cost by 10-fold.  However, there are ways in completing an economic analysis to justify the costs.  For example, most culverts were historically only designed to pass storms up to the 25-year event, but in even more cases, never were sized by engineers.  A larger culvert will increase its capacity and reduce overtopping events that would require road closings and worse, cause the roadway to collapse.  Road closings require emergency management and road crews to set up detours and slowing down commerce, or worse require repetitive reconstruction efforts that, over time, may exceed the cost of installing a Stream Simulation designed culvert.

DSCN2588

Same culvert as in photograph above, after the retrofit using Culvert Simulation. ©Princeton Hydro.

Other ways of encouraging installation of these larger and passable culverts is through the permitting process.  In New England, the US Army Corps of Engineers, allows for a by-pass of a formal review for their approval if the Stream Simulation guidelines are followed. This approach can save a significant amount of time to fast-track a retrofit.  To complement the Corps’ permit facilitation process, the states of Connecticut, Massachusetts, New Hampshire, and Vermont, have developed stream crossing guidelines to meet the Corps’ permit by rule compliance.  These states have even instituted state level regulations requiring aquatic organism passage via the Stream Simulation model.

Princeton Hydro was contracted to design a culvert retrofit to replace a 36 inch diameter culvert with a 12 foot wide arch culvert on a tributary of West Brook which is being monitored as part of the USGS CAFRC research project in Massachusetts.  This retrofit will be used to assess the increase in efficiency of headwater stream accessibility by local brook trout populations.

It would appear that the Stream Simulation or Continuity model is catching on, however, there needs to be more outreach and changes to existing rules in other regions of the US.  Further studies, such as that being conducted by USGS and their partners, will determine the true benefits of increasing culvert fish passage efficiency and bolster the economics of protecting fish populations for future generations.
——-
Geoffrey M. Goll, P.E.
Vice President and Founding Partner

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