How we Manage Fish Passage Barriers on a Watershed Scale

Structures in Waterways summary dashboard

Fish passage barriers are frequently managed on a case-by-case basis. Initially, barriers are identified, characterized, and then subjected to a prioritization scheme. The correction of these barriers typically occurs when funds become available. However, the sheer volume of projects renders this approach impractical. In response to this challenge, our colleagues in New Zealand have pioneered a program aimed at managing fish passage barriers at a watershed scale.

The Structures in Waterways management program, developed by ATS Environmental, integrates a field collection component with a desktop management interface, enabling users to collect and manage data on fish passage barriers. This program operates using commonly utilized GIS and database management software, facilitating seamless integration with existing culvert management programs. Furthermore, it allows users to plan, estimate costs for barrier solutions, and generate reports on the status of barriers at a watershed scale.

The initial step involves uploading existing fish passage barrier information into the database. Newly identified and characterized structures are automatically uploaded to the database through a cloud connection using a field app. Following this, algorithms are employed to prioritize and sort the barriers within the list. The desktop dashboard then provides users with four summary displays, presenting the number, location, and status of the barriers.

Finally, users have the capability to generate reports that estimate costs and schedule barrier remediation. These reports serve as valuable tools for planning future actions or reporting progress to higher levels of authority, showcasing the efforts undertaken to enhance fish passage on a watershed scale.

How We Use the Structures in Waterways Database to Manage Fish Passage Barriers in New Zealand

Here is a summary video of how the Structures in Waterways program is used in New Zealand to manage fish passage barriers on a watershed basis.

Structures in Waterways Field Application

These are three screen shots demonstrating the Structures in Waterways field app. The user collects the necessary information which is then automatically uploaded to the desktop application.

Structures in Waterways Desktop Application

This summary screen allows the user to see the number and status of all the fish passage barriers in a geographic area.

This screens allows the user to see the location and status of all the fish passage barriers in a geographic area.


This screen allows the user to graphically see the status and progression of fish passage barrier assessment and remediation.


This screens allows the user to see the particulars of fish passage barreriers on a watershed scale.


Restoring Nature’s Balance: Coho Salmon Return to Bon Accord Creek in Surrey, British Columbia

Embarking on a project that spans over three decades in my career as a fisheries biologist, I recently experienced one of the most gratifying accomplishments of my journey. After almost 70 years, coho salmon have finally regained access to their spawning habitat in Bon Accord Creek, Surrey, British Columbia.

This achievement was no small feat. Nearly seven decades ago, a railroad company redirected Bon Accord Creek through a 500-foot-long concrete flume, creating a barrier that prevented coho salmon from reaching approximately 2.5 kilometers of vital spawning grounds. Despite commendable efforts by the City of Surrey to enhance upstream salmon habitats, the costs estimated to remove the concrete flume and stabilize the banks were staggering, totaling in the millions of dollars. These costs hindered progress and obstructed the salmon’s migratory path.

To address this challenge, we collaborated closely with the City’s environmental staff, evaluating various solutions. The breakthrough came with the innovative Flexi Baffle system. Working alongside a dedicated group of student volunteers, we strategically installed sixty 2-meter-long Flexi Baffles at intervals along the length of the flume. This installation marked a milestone as the largest of its kind in North America.

The impact was immediate and exhilarating! Following the installation and the onset of significant November rainfall, an adult coho salmon was sighted navigating the native channel above the flume. This marked a monumental success and a testament to the effectiveness of our solution.

To celebrate this milestone, the City held a dedication ceremony on November 24th. The presence and support of Surrey’s Mayor, Council Members, and several Legislative Assembly Ministers underscored the significance of this achievement. The project received well-deserved attention in various newspapers and reports.

This victory, however, is just the beginning of a new chapter. Moving forward, the City is committed to closely monitoring the success of fish passage through Bon Accord Creek, ensuring the sustained return of coho salmon to their spawning grounds.

This triumph serves as a testament to the power of collaboration, innovation, and perseverance in the realm of environmental conservation. It showcases how collective efforts can restore the balance of ecosystems, fostering the return of vital species like the coho salmon to their natural habitats.

The revival of Bon Accord Creek stands as a beacon of hope and inspiration for similar conservation efforts worldwide, reflecting our dedication to preserving and revitalizing the natural world we share. 🌎🐟 #SalmonRevival #EnvironmentalSuccess #BonAccordCreekRestoration

First Coho Salmon in Bon Accord in 70 years.
Mayor of Surey makes comments at
the Bon Accord Creek Fish Passage Dedication

Salmon are able to access spawning habitat in Bon Accord Creek for the first time in almost 70 years.

Another successful Flexi Baffle installation. We worked with the City of Surrey, B.C. and students with the Salmon Habitat Restoration Program (SHaRP) to implement the largest culvert rehabilitation project in North America. A large concrete flume on the Bon Accord Creek, a tributary of the lower Fraser River, has blocked salmon from accessing important salmon spawning habitat for many decades. We worked with City staff to develop a Flexi Baffle installation plan to increase water depth and slow water velocity to create conditions much more conducive to salmon passage.

Below are two strores from local media on the project. Salmon are able to access spawning habitat in Bon Accord Creek for the first time in almost 70 years. Salmon are able to access spawning habitat in Bon Accord Creek for the first time in almost 70 years.

Johnson Creek Watershed Council Success in North Fork of Johnson Creek

The Johnson Creek Watershed Council (JCWC) developed the North Fork Open Migration project conceived as a multi-partner collaboration aimed at eliminating all seven barriers to fish passage in the North Fork of Johnson Creek, near Gresham Oregon. The JCWC worked with a variety of entities to remove, replace and/or repair culverts that were a barrier to fish passage.

In 2018, JCWC made history becoming the first practitioner in North America to utilize the Flexi Baffle culvert retrofit technology to improve fish passage through culverts that are not planned to be replaced. The Flexi Baffle, developed by ATS Environmental from New Zealand creates step pools in a culvert to improve fish passage. Water velocities are reduced, and water depth increased, all to improve fish passage. ATS began working with their partner SSA Environmental to bring their unique fish passage technologies to North America. Since that time, JCWC has installed Flexi Baffles in two additional culverts.

This story describes the work and success of the Johnson Creek Watershed Council in improving fish passage.

Municipal Water Leader interview with Shane Scott on the Flexi Baffle

Reporters with the Municipal Water Leader magazine interviewed Shane Scott, owner of SSA Environmental, on his experience with the Flexi Baffle. The Flexi baffle is a flexible weir that is installed in culverts to improve fish passage. In this interview they discuss the history of the Flexi Baffle, some current applications and the future of SSA Environmental.


Students at Work!

Another successful Flexi Baffle installation. We worked with the City of Surrey, B.C. and students with the Salmon Habitat Restoration Program (SHaRP) to implement the largest culvert rehabilitation project in North America. A large concrete flume on the Bon Accord Creek, a tributary of the lower Fraser River, has blocked salmon from accessing important salmon spawning habitat for many decades. We worked with City staff to develop a Flexi Baffle installation plan to increase water depth and slow water velocity to create conditions much more conducive to salmon passage.

Flexi Baffles
Bon Accord Creek before Flexi Baffle Installation

SSA Environmental staff then worked to train SHaRP students and project managers to install Flexi Baffles at predetermined intervals through the flume. Students isolated the project area with barrier nets. They then installed Flexi Baffles using concrete drills and wedge anchors.

Students encountered masses of blackberry briars and tough access conditions, but they persevered. And the results speak for themselves!

Students will now monitor fish passage this fall as salmon begin their spawning migration.

Here are the Flexi Baffles after a significant rain event. Note the resting areas between each Flexi Baffle.

Note resting bools between each Flexi Baffle.

Flexi Baffle Installation in Washington State

Flexi Baffle Installation in Terrell Creek

The Nooksack Salmon Enhancement Association (NSEA) is a community-based, non-profit organization focused on reversing the trend of declining salmon runs in Whatcom County in Washington State. The NSEA works to enhance river and riparian habitat to support salmon recovery. They also work to educate people of all ages on how to provide Pacific salmon and steelhead with the best chance at survival.

We were contacted by the NSEA to develop a Flexi Baffle installation in a large box culvert on Terrell Creek, a tributary to Birch Bay on the Northern Puget Sound. The purpose of the project was to improve passage conditions for Pacific salmon migrating to their spawning grounds. This video documents the installation of the Flexi Baffles by NSEA staff.

Exciting Development in the Science of Improving Fish Passage Through Culverts

The Fish Passage Action Team is an international coalition of people working to improve fish passage through road culverts and other conveyances. We have developed a variety of systems to improve the hydraulics in culverts and other conveyances to create better passage conditions for a variety of fishes and other aquatic organisms.

We recently began developing Computational Fluid Dynamic (CFD) models to demonstrate the effects if the Flexi Baffle on hydrology of a culvert. We have developed baseline CFD models to assess the spacing and configuration of Flexi Baffles to create the conditions to meet various fish passage standards such as water depth and velocity.

We can now also provide an interested party an evaluation of your specific project site. We can use the actual dimensions, configuration and expected flows through your culvert, and we can develop a recommended Flexi Baffle installation. We can also provide the CFD modeling results that demonstrate that your Flexi Baffle installation is meeting the intended fish passage conditions. The link below is a Fish Passage Action Team newsletter on the first CFD model outputs.

Researchers Evaluate the Flexi Baffle to Improve Fish Passage through a Culvert in New York State

The New York Department of Environmental Conservation (DEC) is working in cooperation with Trout Unlimited to study fish passage through a perched culvert within the Beaver Kill drainage in Delaware County. DEC staff installed Flexi Baffles in a culvert to improve fish passage.

They are now using RFID fish tag technology to evaluate the passage of three trout species through the culvert outfit with Flexi Baffles. The DEC created a great video explaining this project. We look forward to working with these groups on future successful fish passage projects. Please contact us if you need information on the #flexibaffle. #TU #fishpassage #culvert #conservation

The Idaho Department of Fish and Game Used Culvert Baffles to Expand Steelhead Habitat

The IDFG used genetic testing to evaluate the success of installing baffles in a culvert on the Potlatch River in the Clearwater Basin. The state installed baffles in a culvert in an effort to help anadromous steelhead access historic spawning habitat. Researchers used genetic monitoring to observe how in just two years the composition of salmonids above the culvert was moving from the resident rainbow trout to the ocean-going life history of steelhead. Steelhead were again able to access historic spawning habitat.

Excellent Drawings Clearly Show Fish Passage Remediation Techniques

Our friends in New Zealand have developed some pen and ink illustrations of the Flexi Baffle installed in a culvert to improve fish passage. There is also an illustration of a modified Flexi Baffle installation equipped with spat rope. This type of application is intended for passage of weak swimming species such as eels.

The First Flexi Baffle Installation in North America

The Johnson Creek Watershed Council (JCWC) is a successful watershed restoration group focusing on Johnson Creek, a tributary to the Willamette River near Portland Oregon. Led by Executive Director Daniel Newberry, the JCWC works with the community to plan and implement a variety of volunteer and restoration activities in the Johnson Creek Basin. We worked with Restoration Project Manager Chuck Lobdell to complete the first Flexi Baffle installation in North America.

The JCWC wanted to improve fish passage through a 40-foot-long concrete culvert in the North Fork Johnson Creek Watershed. They found that coho salmon would exploit available habitat above the culvert of passage conditions were improved.

The video below demonstrated the results of the Flexi Baffle installation. The JCWC staff demonstrates how the flexible baffles interrupts laminar flow through the culvert and created resting pools which would allow fish to more easily pass through the culvert.

The JCWC installed Flexi Baffles in another culvert just upstream of that site. We will keep you posted on how it worked when we go out and inspect this summer. Stay tuned!

How to Maintain Hydraulic Capacity of Culverts & Protect the Fish with Shane Scott

I talked with Cassie Jordan about culverts and fish passage. This was my first podcast and it was a lot of fun!

Here is how Cassie introduced the podcast.

Join Cassie Jordan and Shane Scott, owner of SSA Environmental LLC, to learn how installing flexible culvert baffles is an easy and inexpensive method to improve fish passage through culverts. Salmon, trout, and other fish and aquatic species are often blocked from their habitat by poorly designed or constructed culverts. Repairing or removing culverts is costly and requires considerable time and resources. SSA has developed culvert baffles that improves fish passage in an effective and economic manner.

About Shane Scott: Shane has over 30 years’ experience working with fish passage and water quality issues. He works with utilities and other industries in minimizing adverse effects of developments on fish and wildlife resources in a cost-effective manner. Shane has worked with Clients to development and implement a variety of fish and wildlife mitigation measures that are both biologically effective and cost efficient. He has also worked on some of the largest and most complex fish passage projects in North America.

Improve fish passage with the Flexi Baffle

Check out this video of several Flexi Baffles in culverts throughout North America. The Flexi Baffle creates hydraulic conditions to improve the passage of fish and eels and other aquatic organisms. The flexible baffle material allows rocks, logs and other debris to pass through the culvert which eliminates expensive and dangerous maintenance required to remove the material. Also, the flexible baffles bend lay flat at high water, so they have minimal effect on culvert capacity.