Self-Sustaining Culverts

Resilience for streams, habitats, and communities.

Ausable Freshwater Center

It's simple. When roads cross rivers or streams, a bridge or culvert is inevitable. In the Adirondacks, road stream crossings are ubiquitous—numbering in the hundreds in most towns. Town roads, county roads, and state roads cross streams large and small. Historically, building these stream crossings prioritized road safety and cost efficiency. Little thought was given to stream health, aquatic wildlife passage, or the potential for complications in large storms and resulting flood events.

Undersized, collapsed, or poorly designed stream crossings disrupt natural stream function, fragment ecosystems, exacerbate erosion, and make roads vulnerable during floods. High flows during intense rainstorms increase stream channel water volume and velocity. Undersized or poorly designed culvert pipes concentrate those flows, creating a firehose effect and eroding the bed and banks at pipe outlets, creating large drop-offs to the streams below. Such "perched" culverts make it difficult or impossible for fish to migrate upstream to forage, breed, or seek cooler waters. On the upstream end, debris builds up quickly above undersized culvert pipes, backing up natural flows, undermining roads, flooding homes and businesses, compromising public safety, increasing emergency costs, and requiring ongoing maintenance by local road crews.

Fortunately, there's a solution. Since 2009, the Ausable Freshwater Center (AFC) has been working with communities and partners to address this challenge. We've developed and tested a cost-effective culvert model to manage flood flows, protect stream health, ensure wildlife passage, reduce emergency costs and damage to public and private infrastructure. Our self-sustaining culverts are sized at 125% of bankfull width to carry a 100-year flood at 80% of their capacity. They improve public safety by allowing high flows to pass freely, reducing damage to roads and property as well as emergency response costs. Appropriately sized culverts and healthy restored streams shrink municipal maintenance costs in the long-term. A self-sustaining culvert is expected to last at least 70 years, and a road crew doesn’t need to worry about it in a storm.

It's a win for our communities, a win for aquatic wildlife, and a win for the streams we cherish. See the arc of our project efforts in the map below.

Our Projects

Click on a photo or point in the map below to learn more about our self-sustaining culvert projects – 12 so far, including five that use our self-sustaining model, and more to come. We're tackling the highest priority culverts, working side-by-side with town and county road crews. Once completed, these culverts are more resilient to increased storm/flood frequency and intensity as well as increased periods of drought. Our self-sustaining culvert model was built in the Ausable River watershed but we've exported it to Lake George and to the Boquet watershed.

The map below shows the location of the projects within the Ausable watershed (dark blue line) and where along a stream they are (light blue lines).

Lewis Brook, Jay - 2012

Palmer Brook (Dry Bridge Road), Black Brook - 2014

Palmer Brook (Separator Rd), Black Brook - 2014

Holcomb Brook, North Elba - 2015

Roaring Brook, North Elba - 2015

Courtney Brook, Wilmington - 2015

Otis 1, Jay - 2016

New Bridge Brook, Wilmington - 2016

Rocky Branch Tributary, Jay - 2017

Otis 3 Retrofit, Jay - 2019

Potash, Jay - 2020

Otis 2, Jay - 2020

Lewis Brook, Jay - 2012

This undersized crossing on Bartlett Road at Lewis Brook, a tributary of the East Branch Ausable River, was compromised during Hurricane Irene flooding. The crossing was replaced by the Town of Jay with support from Essex County DPW and input from the US Fish and Wildlife Service. AFC coordinated the Service's involvement working in partnership with The Nature Conservancy. A 4-sided box culvert sized to appropriate width was used to replace the old, undersized metal pipes. This project, while successful in managing flows, reinforced the need for open bottom structures, native materials, and function-based restoration of the stream channel.

Palmer Brook (Dry Bridge Road), Black Brook - 2014

In 2014, AFC teamed with The Nature Conservancy and the U.S. Fish and Wildlife Service to retrofit the crossings of Palmer Brook at Dry Bridge and Separator Roads (see next project). Both bridges are undersized but the cost of replacing them was too high for the small Town of Black Brook. Instead, the town's highway department worked with the Service and AFC on a lower cost solution: restore the stream channel, recreating its native form and function through the bridge structures to enhance its capacity to move water and sediment in storms and allow fish passage for its native brook trout.

Palmer Brook (Separator Rd), Black Brook - 2014

The second of two retrofit projects over Palmer Brook rebuilt the stream above, through, and below the existing bridge. Based on geomorphic surveys by the Service and AFC, both projects used local quarry stone to reconstruct the forms that would ensure this native brook trout stream could manage flows at both intersections. The Separator Road project created a deep pool and riffle sequence while the Dry Bridge project installed a multiple step-pool system. Both projects succeeded in managing flood flows, reestablishing habitat, and allowing aquatic organism passage.

Holcomb Brook, North Elba - 2015

AFC and the U.S. Fish and Wildlife Service served as advisors for two River Road culvert replacements, Holcomb and Roaring Brooks, funded by TNC and engineered and constructed by Essex County in 2015. In each case, the width of the two streams as they crossed under River Road and entered the West Branch Ausable River required a replacement structure over 20 feet. At that size, New York State defines such culverts as bridges. These were complex projects that required exceptional patience and a great deal of problem solving by all the partners. In the photo above, the Essex County crew works to remove the undersized pipe culvert that once held Holcomb Brook. The brook is secured in another pipe flowing safely around the worksite.

Roaring Brook, North Elba - 2015

Roaring Brook is the second of the two culverts replaced by bridges thanks to a partnership between Essex County, TNC, AFC, and the US Fish and Wildlife Service. The undersized pipes of both crossings created frequent upstream flooding in storms that washed over River Road. Downstream, both culverts were perched. Both Roaring and Holcomb Brooks held small populations of brook trout. The undersized culverts with their perched outlets prevented migration upstream for these native trout. Once opened, aquatic passage from the West Branch into each stream was again possible for these native fish but also for non-native populations of brown trout.

Courtney Brook, Wilmington - 2015

The Courtney Brook crossing on Lenny Preston Road in Wilmington was the first AFC-led culvert replacement. Taking lessons from our partnership projects above and with funds from the Doris Duke Foundation via our partner TNC, we installed an open bottom culvert using an aluminum arch. The process was challenging and full of learning. We relied on the expertise of our colleagues at the USFWS Cortland Field Office, the skill of our engineering partners at Northwoods Engineering, and a smart team of DPW employees from the Towns of Wilmington and Jay.

We prioritized the use of native stone to repair the streambed instead of blasted quarry stone. We built grade controls that blended into the streambed instead of forms that looked artificial. We reseeded with regionally appropriate native grasses. These were lessons learned from prior culverts and inspired our philosophy to go beyond aquatic organism passage and prioritize restoring the stream.

Otis 1, Jay - 2016

An unassuming little stream dropping steeply out of the Jay Mountain Wilderness, Otis Brook is a haven for brook trout and a myriad of aquatic organisms. It is challenged by its road crossings. We began our work to improve the stream's health, road safety in storms, and repair the challenges to aquatic wildlife passage with this project. Once again, we teamed with the USFWS and the dedicated staff of the Town of Jay Highway Department. For years, this undersized culvert threatened the road. Its outlet was perched 7 feet above the streambed. We swapped the 4-foot diameter culvert for a 17-foot wide aluminum arch. We restored the streambed, building a series of steps and pools with native stone and set the arch at the same slope, 6.7%, as the streambed.

Within 24 hours of completing the job, brook trout were moving through the step-pool system.

New Bridge Brook, Wilmington - 2016

AFC, with input from the USFWS, provided a survey, construction advice, and permitting support to the Essex County DPW as they engineered and built a bridge replacing an undersized culvert on Haselton Road. Sitting just below a wetland, the final stage of the work involved construction of a stream channel grade control just above the bridge to hold the slope of the stream and the water level of the wetland. AFC staff teamed with US Fish and Wildlife staff to guide this work.

Rocky Branch Tributary, Jay - 2017

The AFC culvert on a Rocky Branch tributary under Nugent Road in the Town of Jay combined all our experience to create our current model. With this installation, the self-sustaining culvert reached a new standard.

Prior to our work, the deteriorating and undersized pipes under Nugent Road were overwhelmed in every storm. The dead-end road was seasonally impassable for residents, emergency services, and for access to Town of Jay water supply infrastructure. This was our first project with the team from Zielinski's Construction. For this project we changed our footer design creating greater clearance for streambed reconstruction and increasing construction efficiency.

The result combined stream restoration with road crossing replacement, creating a lasting solution for the Town of Jay and a richer ecosystem for brook trout.

Otis 3 Retrofit, Jay - 2019

Retrofits are a second-best alternative for a road-stream crossing made necessary because the cost of bridge replacement is just too high. Otis Brook is the downstream-most tributary of the East Branch Ausable River with a healthy population of brook trout and no brown trout incursion. Making this crossing fish passable was critical to freeing the upstream half of the Otis watershed.

Working with Mike Ward of Ward Logging we rebuilt the 100' of streambed immediately below the undersized, badly skewed concrete bridge under Glen Road. We raised the streambed using native material, created a pool-step system and rebuilt the banks—all to precise specifications.

Retrofits may not last as long as replacements and may be challenged by large storms. This crossing continues to allow fish passage.

Potash, Jay - 2020

Sometimes healthy populations of brook trout show up in the most amazing places. Tiny little Potash Brook runs along a busy town road, through a development and then on to the East Branch Ausable River. This culvert was identified as a priority for community resilience in the 2013 NY Rising Community Reconstruction Plan funded by the Governor’s Office of Storm Recovery. This was the second culvert we constructed in 2020 and was especially challenging because the road could not be closed during construction. The 40-inch diameter culvert pipe that had deteriorated, causing the road to buckle, was replaced with a 19-foot wide aluminum arch. Work was completed by Zielinski's Construction.

We hope to completely open this small system by replacing the farthest upstream culvert.

Otis 2, Jay - 2020

In order to move this meandering section of Otis brook under the road, decades ago, a road crew decided to shift the path of the brook. They blocked its flow with large boulders and earth where it met the road, forcing the brook to turn 90 degrees into a roadside ditch. The brook ran in the ditch for 100 feet before making a 90 degree turn into a 4-foot diameter pipe. In storms, the ditch couldn't manage the water flows. The result was frequent flooding and gradual undermining of the road along the ditch.

To do this replacement correctly, we decided the brook must be returned to its original path. The challenge was to define that path using the evidence the current stream could give us, engineering the new path and culvert, and reconnecting the stream. The resulting culvert, running diagonally under the road was 63 feet long and 16 feet wide. As we built the new streambed, we found evidence of the former streambed, confirming our design. Within hours of restoring flows, the resident brook trout agreed by swimming upstream to the delight of our construction crew.

What's Next?

Our self-sustaining culvert work is just getting started. We've learned so much from each of these projects, our partners and construction teams, and we look forward to putting these experiences to use in watersheds throughout the Adirondack Park.

We are currently focused on projects in the Ausable, Boquet, and Saranac watersheds:

  • Identifying the next priority culverts for survey and design in the Ausable watershed.
  • Assisting partners in the Boquet watershed to advance two priority culvert replacements in the Town of Lewis and two private stream crossing replacements in the Town of Willsboro.
  • Working with partners to review and address culvert needs in the Saranac watershed.

Thank You

These projects would not be possible without the support of our partners and funders.

Thank you to our community partners: the towns of Wilmington, North Elba, Jay, and Black Brook, Essex County, Lake George Association, and the Essex County Soil and Water Conservation District.

Thank you to our agency partners: the U.S. Fish and Wildlife Service, Cortland Field Office and the U.S. Fish and Wildlife Service, Lake Champlain Field Office.

Thank you to our funders: Lake Champlain Basin Program, NEIWPCC, The Nature Conservancy, Patagonia, US Fish and Wildlife Service, New York State Department of State, New York State Department of Environmental Conservation.