Dam Removal on the Moosup River

Moosup River

The Moosup River is a beautiful 30-mile-long, trout river flowing through Connecticut and Rhode Island, eventually emptying into the Quinebaug River.

Several dams, most originally built in the 1800s or early 1900s, impeded the river’s natural flow, impaired habitat, fragmented the river system, and prevented fish from swimming upstream to their native spawning grounds.

In 2013, American Rivers, CTDEEP Fisheries, and Natural Resources Conservation Service began collaborating on the removal of multiple dams and remnant dams as part of a larger project to restore connectivity to the Moosup River in the Town of Plainfield. Princeton Hydro and RiverLogic Solutions were contracted to provide design-build and permitting services.

As part of this larger multi-year effort, five dams are planned for removal from the Moosup River. The most downstream barrier, the Hale Factory Dam was removed in 2014. The remnants of the toppled Griswold Rubber Dam were removed in 2015. In 2017, the removal of Brunswick Mill Dam #1 was completed. And, two more dams, downstream of New Brunswick Mill Dam #1, are currently under consideration for removal. When fully completed, the Moosup River Dam Removal Project will reconnect fish habitats along 6.9 miles of the Moosup River.

 

Hale Factory Dam

The Hale Factory Dam was constructed of a boulder core capped in a one-foot-thick concrete layer. The dam was partially breached as the concrete cap had deteriorated severely over the years, allowing flow to pass between boulders and allowing the normal pool elevation to drop substantially from its former design height.

The resource delineation conducted on site identified a vernal pool with an 18 inch culvert outlet that discharged 90 feet upstream of the dam. To preserve this ecological resource on the site, the vernal pool was not disturbed during the dam removal.

Princeton Hydro provided a field assessment, sediment characterization and analysis, final design and permit application package for the full removal of the Hale Factory Dam. Full removal of the dam entailed demolition and removal of the concrete, and re-use of the natural cobbles and boulders from the dam to create in-stream habitat features. Once completed, the river and its boulders appeared as if placed by nature itself, with the former dam’s presence indicated only by the age-old lichen covered field stone walls leading up to the banks.

 

Griswold Rubber Dam

The Griswold Rubber Dam was in a gravel-cobble reach of the river approximately 80 feet wide in the Village of Moosup and was adjacent to the 1992 expansion of the Griswold Rubber factory.  At one time, the dam stood approximately 10 feet high and 150 feet long. The dam was constructed of a large segmented concrete slab that had since toppled over and was lying nearly flat on the river bed in multiple sections. The dam structure, having failed, served no useful purpose. Despite being toppled, the dam still presented a deterrent to the effective movement of aquatic organisms at normal to low flows and was therefore worthy of complete removal to restore river connectivity.

Princeton Hydro conducted an initial field investigation with RiverLogic Solutions to gain insights regarding the construction approach. Princeton Hydro then followed-up with a more detailed assessment of river bed sediment, geomorphic conditions, the likely riverine response, construction access, and other design related issues that were incorporated into design plans and permit applications. The restoration design Princeton Hydro developed aimed to remove the partial barrier to fish passage with as little disturbance to surrounding infrastructure and resources as possible.

 

Brunswick Mill Dam #1

This dilapidated timber crib dam stood approximately 4-feet high and spanned the channel at approximately 130 feet. The timbers ranged from 1.5 to 2.5 feet in diameter and over 20 feet in length; 50 were integrated into the dam. The timber crib was filled with gravel and other debris, and the gravel substrate extended 50 feet upstream. The original dam was significantly higher, but the timber crib spillway deteriorated and gradually collapsed over time and only a portion of the structure remained.

For this project, Princeton Hydro completed sediment investigation, sampling and analysis; hydrologic and hydraulic analysis; and provided design and engineering for full removal of the dam. Princeton Hydro contracted with an archeologist / industrial historian, and together closely observed the dam deconstruction to observe and record how the timber crib had been assembled. Multiple types of iron pins and wooden pegs revealed how the dam had been repaired over the years – findings, old maps, and photos were incorporated into a historical report filed with the state historic preservation office. Princeton Hydro coordinated to have the old timbers salvaged for eventual re-use. Removing the Brunswick Mill Dam #1 was a continuation of the large scale Moosup River restoration effort and paved the way for the potential removal of two more dams downstream in the coming years.

“When a dam is breached and taken out, the tangible results are very quickly noticeable,” said Paul Woodworth, Princeton Hydro Fluvial Geomorphologist. “The return of migratory fish is a very strong indicator of the ecological benefits of dam removal – sometimes after a removal you can see fish immediately swimming upstream. Removing dams also improves safety in nearby communities, reestablishes the natural flow of sediment, improves water quality, provides new recreation opportunities, and restores habitats for fish and wildlife.”

Click here to read more about Princeton Hydro’s engineering services for the restoration and removal of dams.

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.

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.