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.

6 Tips to Prepare Your Pond for Spring

It’s officially time to say good-bye to winter and “spring” your pond out of hibernation mode. We’ve put together six tips for getting your pond ready for Spring and ensuring it remains healthy all year long.

1. Spring Cleaning Your Pond

The first step in preparing your pond for Spring is to give it a thorough cleaning. Remove leaves, debris and any surface algae that may have accumulated over the winter. For shallow ponds, you may be able to use a net or pond rake to remove debris and sediment from the bottom and along the perimeter of the pond.

2. Inspect Your Pond for Damage

Inspect your pond, including berms, outlet structures and trash racks for any damage that may have occurred over winter due to ice. If you observe any damage, contact Princeton Hydro immediately. One of our engineers can determine if the damage is superficial or requires more significant repairs. Also, if your pond is equipped with an aeration system, before starting it up, contact us to schedule a system inspection. A thorough inspection and proper start-up procedure will ensure the system remains fully and effectively operational for the entire summer.

3. Put Your Pond to the Test

The routine testing of your pond’s water quality is an important part of preventing harmful algae growth, fish kills and other problems. Princeton Hydro professionals can conduct a “Spring start up” water quality analysis of your pond. The resulting data will enable us to develop pro-active, eco-friendly approaches to control nuisance aquatic species and promote environmental conditions supportive of a healthy and productive fishery.

4. Recognize and Reduce Erosion by Aquascaping the Shoreline

It’s important to check the pond’s shoreline for any signs of erosion, which can be easily stabilized by planting native, riparian plants. This is called “aquascaping”. Aquascaping is a great way to beautify the shoreline, stabilize erosion problems, create fish and amphibian habitat, attract pollinating species and song birds, and decrease mosquito breeding.

Our pond and wetland scientists can design and construct a beautiful, highly functional aquascaped shoreline for your pond.

5. Consider Installing an Aeration System

Sub-surface aeration systems eliminate stagnant water and keep your pond thoroughly mixed and properly circulated. Sub-surface aeration systems are the most cost-effective and energy-efficient way to maintain proper pond circulation. Proper aeration enhances fish habitat, minimizes the occurrence of algae blooms, and prevents mosquito breeding. Contact us to discuss if aeration is the right solution for you. If it is, we can design and install the appropriate system for your pond.

6. Have an Ecologically Balanced Pond Management Plan

There is more to pond management than weed and algae treatments alone. There is also a big difference between simple pond maintenance and ecologically-based pond management. A customized pond management plan developed by a Princeton Hydro professional is the “blueprint” you need to proactively care for your pond in a very environmentally responsible manner.

Our Certified Lake and Pond Managers will assess the status of your pond and provide you with an environmentally holistic management plan that is based on the unique physical, hydrologic, chemical and biological attributes of your pond. The plan will identify the causes of your pond’s problems and provide you with the guidance needed to correct these problems. The results are far more environmentally sustainable than simple (and often unnecessary) reactive weed and algae treatments.

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These are just a few tips to get your pond ready for a new season of enjoyment. Princeton Hydro can help you every step of the way. Our success in caring for ponds, lakes and reservoirs is the result of starting with the right plan and applying customized, environmentally-sound management techniques. Please contact us to discuss your pond management needs and to schedule an assessment.