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Brett Towler, Ph.D., P.E.

Dr. Brett Towler is the Fish Passage Design & Analysis Team Supervisor and Senior On-Site Manager at the Eastern Ecological Science Center's S.O. Conte Research Laboratory in Turners Falls, MA.

Professional Experience

  • USFWS Regional Fish Passage Engineer, Northeast Region 2010-2021

Education and Certifications

  • Ph.D., Engineering, Montana State University-Bozeman

  • M.S., Civil Engineering, Montana State University-Bozeman

  • B.S., Civil Engineering, University of Massachusetts-Amherst

Affiliations and Memberships*

  • Professional Engineer (P.E.), Maine, Board of Licensure for Professional Engineers, Augusta, Maine

  • Professional Hydrologist (P.H.), Surface Water, American Institute of Hydrology, Carbondale, Illinois

Science and Products

Fishway entrance gate experiments with adult American Shad

The goal of this multiyear study was to examine how changes to an upstream fishway entrance impacted the passage rate of adult American shad (Alosa sapidissima). We evaluated a total of nine treatment conditions that consisted of three fishway entrance gate types and three submergence depths (i.e., the water surface elevation of the tailwater relative to the height of the gate crest). Approximatel
Authors
Kevin Mulligan, Alexander J. Haro, Brett Towler, Bryan Sojkowski, John Noreika
By
Ecosystems Mission Area, Eastern Ecological Science Center

Downstream fish passage guide walls: A hydraulic scale model analysis

Partial-depth guide walls are used to improve passage efficiency and reduce the delay of out-migrating anadromous fish species by guiding fish to a bypass route (i.e. weir, pipe, sluice gate) that circumvents the turbine intakes, where survival is usually lower. Evaluation and monitoring studies, however, indicate a high propensity for some fish to pass underneath, rather than along, the guide wal
Authors
Kevin Mulligan, Brett Towler, Alexander J. Haro, David P. Ahlfeld
By
Ecosystems Mission Area, Species Management Research Program, Eastern Ecological Science Center

Sensitivity of the downward to sweeping velocity ratio to the bypass flow percentage along a guide wall for downstream fish passage

Partial-depth impermeable guidance structures (or guide walls) are used as a method to assist in the downstream passage of fish at a hydroelectric facility. However, guide walls can result in a strong downward velocity causing the approaching fish to pass below the wall and into the direction of the turbine intakes. The objective of this study was to describe how the ratio of the vertical velocity
Authors
Kevin Mulligan, Brett Towler, Alexander J. Haro, David P. Ahlfeld
By
Ecosystems Mission Area, Species Management Research Program, Eastern Ecological Science Center

A computational fluid dynamics modeling study of guide walls for downstream fish passage

A partial-depth, impermeable guidance structure (or guide wall) for downstream fish passage is typically constructed as a series of panels attached to a floating boom and anchored across a water body (e.g. river channel, reservoir, or power canal). The downstream terminus of the wall is generally located nearby to a fish bypass structure. If guidance is successful, the fish will avoid entrainment
Authors
Kevin Mulligan, Brett Towler, Alexander J. Haro, David P. Ahlfeld
By
Ecosystems Mission Area, Species Management Research Program, Eastern Ecological Science Center

Derivation and application of the energy dissipation factor in the design of fishways

Reducing turbulence and associated air entrainment is generally considered advantageous in the engineering design of fish passage facilities. The well-known energy dissipation factor, or EDF, correlates with observations of the phenomena. However, inconsistencies in EDF forms exist and the bases for volumetric energy dissipation rate criteria are often misunderstood. A comprehensive survey of EDF
Authors
Brett Towler, Kevin Mulligan, Alexander J. Haro
By
Ecosystems Mission Area, Eastern Ecological Science Center

Non-USGS Publications**

Towler, B., Hoar, A., and Ahlfeld, D. 2012. Ecohydrology and Fish Passage Engineering: the legacy of Denil and the call for a more inclusive paradigm. Journal of Water Resources Planning and Management 138(2) 77-79. https://doi.org/10.1061/(ASCE)WR.1943-5452.0000185

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

link
ABiKiS Burst Flume

Fish Passage Design and Analysis at the S.O. Conte Research Laboratory

There are more than 92,000 dams in the United States, of which at least 3% of these produce hydropower. Hydropower projects create renewable energy but also can alter habitats, restrict upstream and downstream movements of fishes and other aquatic organisms, and may stress, injure or kill migrant fishes and other aquatic organisms. In addition, there are more than 5 million culverts and other road...
By
Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Chesapeake Bay Activities, Eastern Ecological Science Center
link

Fish Passage Design and Analysis at the S.O. Conte Research Laboratory

There are more than 92,000 dams in the United States, of which at least 3% of these produce hydropower. Hydropower projects create renewable energy but also can alter habitats, restrict upstream and downstream movements of fishes and other aquatic organisms, and may stress, injure or kill migrant fishes and other aquatic organisms. In addition, there are more than 5 million culverts and other road...
Learn More
Water is discharged through two adjacent 4-foot-wide wooden, baffled channels in a 10-foot wide concrete flume.
link
Comparison of the novel D-Cylinder and standard Denil fish ladders
Scientist standing in water inside a flume at the Conte Lab's fish passage complex
link
Aaron Heisey and EESC colleagues enter the east flume in the Conte Lab's Fish Passage Complex after the conclusion of a study trial to recover adult white suckers
3 men hold a 9 foot tall wood frame upright in a parking lot
link
Constructing a Denil fishway baffle
Two men standing next to a steel I-beam structure in a 10-foot wide concrete flume.
link
Steel support structure installed for fish ladder experiment
Aerial photo of a laboratory campus consisting of 5 main buildings surrounded by trees and located between a canal and a rive
link
Aerial photo of the USGS Conte Research Laboratory
Two men plant a pollinator garden
link
Planting the pollinator garden at the Conte Lab
Man works sluice pipe in to the tank of a fish transport truck
link
Collecting shad for study at Holyoke fish lift
Water runs through a screen and discharged from a 4-foot opening in a 20-foot concrete flume located in a large building.
link
Palisade study trials in the Fish Passage Complex with American shad
Two men wearing waders drag a net between them to herd fish into a concrete channel.
link
Seining fish into the Burroughs Pond following the first shad trial
Man stands on grating above a watered flume. Below, American shad school in the pool.
link
The first shad trial in the Palisade Entrance is complete
Man wearing waders carries live American shad; shad has been implanted with PIT tag in dorsal fin.
link
Tagging and measuring American shad for the Palisade fishway study
Man uses pliers to secure solenoid assembly to instrument housing on the back of a fish transport truck.
link
Adjustments to the O2 delivery system on Conte's fish truck
Two stories of scaffolding assembled with four solar panels on top, facing south.
link
Solar Panel Installation
3 men pose in front of a 23 foot long boat sitting on a trailer adjacent to a garage
link
Final preparations for the 2022 Delaware River American shad study
Man kneels next to the carcass of a 7.5 ft long Atlantic Sturgeon.
link
Atlantic sturgeon recovered for necropsy
Alex Haro clearing flume during lamprey study
link
Alex Haro clearing flume during lamprey light study
From the banks of a drained 500 ft wide canal with substation in the background and a 4 foot trap sitting in 10 foot wide riv
link
Juvenile lamprey collection in the power canal
link

USGS research helps American shad find their way

Science takes time.

Read Article

Science and Products

  • Publications

    Fishway entrance gate experiments with adult American Shad

    The goal of this multiyear study was to examine how changes to an upstream fishway entrance impacted the passage rate of adult American shad (Alosa sapidissima). We evaluated a total of nine treatment conditions that consisted of three fishway entrance gate types and three submergence depths (i.e., the water surface elevation of the tailwater relative to the height of the gate crest). Approximatel
    Authors
    Kevin Mulligan, Alexander J. Haro, Brett Towler, Bryan Sojkowski, John Noreika
    By
    Ecosystems Mission Area, Eastern Ecological Science Center

    Downstream fish passage guide walls: A hydraulic scale model analysis

    Partial-depth guide walls are used to improve passage efficiency and reduce the delay of out-migrating anadromous fish species by guiding fish to a bypass route (i.e. weir, pipe, sluice gate) that circumvents the turbine intakes, where survival is usually lower. Evaluation and monitoring studies, however, indicate a high propensity for some fish to pass underneath, rather than along, the guide wal
    Authors
    Kevin Mulligan, Brett Towler, Alexander J. Haro, David P. Ahlfeld
    By
    Ecosystems Mission Area, Species Management Research Program, Eastern Ecological Science Center

    Sensitivity of the downward to sweeping velocity ratio to the bypass flow percentage along a guide wall for downstream fish passage

    Partial-depth impermeable guidance structures (or guide walls) are used as a method to assist in the downstream passage of fish at a hydroelectric facility. However, guide walls can result in a strong downward velocity causing the approaching fish to pass below the wall and into the direction of the turbine intakes. The objective of this study was to describe how the ratio of the vertical velocity
    Authors
    Kevin Mulligan, Brett Towler, Alexander J. Haro, David P. Ahlfeld
    By
    Ecosystems Mission Area, Species Management Research Program, Eastern Ecological Science Center

    A computational fluid dynamics modeling study of guide walls for downstream fish passage

    A partial-depth, impermeable guidance structure (or guide wall) for downstream fish passage is typically constructed as a series of panels attached to a floating boom and anchored across a water body (e.g. river channel, reservoir, or power canal). The downstream terminus of the wall is generally located nearby to a fish bypass structure. If guidance is successful, the fish will avoid entrainment
    Authors
    Kevin Mulligan, Brett Towler, Alexander J. Haro, David P. Ahlfeld
    By
    Ecosystems Mission Area, Species Management Research Program, Eastern Ecological Science Center

    Derivation and application of the energy dissipation factor in the design of fishways

    Reducing turbulence and associated air entrainment is generally considered advantageous in the engineering design of fish passage facilities. The well-known energy dissipation factor, or EDF, correlates with observations of the phenomena. However, inconsistencies in EDF forms exist and the bases for volumetric energy dissipation rate criteria are often misunderstood. A comprehensive survey of EDF
    Authors
    Brett Towler, Kevin Mulligan, Alexander J. Haro
    By
    Ecosystems Mission Area, Eastern Ecological Science Center

    Non-USGS Publications**

    Towler, B., Hoar, A., and Ahlfeld, D. 2012. Ecohydrology and Fish Passage Engineering: the legacy of Denil and the call for a more inclusive paradigm. Journal of Water Resources Planning and Management 138(2) 77-79. https://doi.org/10.1061/(ASCE)WR.1943-5452.0000185

    **Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

  • Science
    link
    ABiKiS Burst Flume

    Fish Passage Design and Analysis at the S.O. Conte Research Laboratory

    There are more than 92,000 dams in the United States, of which at least 3% of these produce hydropower. Hydropower projects create renewable energy but also can alter habitats, restrict upstream and downstream movements of fishes and other aquatic organisms, and may stress, injure or kill migrant fishes and other aquatic organisms. In addition, there are more than 5 million culverts and other road...
    By
    Ecosystems Mission Area, Biological Threats and Invasive Species Research Program, Species Management Research Program, Chesapeake Bay Activities, Eastern Ecological Science Center
    link

    Fish Passage Design and Analysis at the S.O. Conte Research Laboratory

    There are more than 92,000 dams in the United States, of which at least 3% of these produce hydropower. Hydropower projects create renewable energy but also can alter habitats, restrict upstream and downstream movements of fishes and other aquatic organisms, and may stress, injure or kill migrant fishes and other aquatic organisms. In addition, there are more than 5 million culverts and other road...
    Learn More
  • Multimedia
    Water is discharged through two adjacent 4-foot-wide wooden, baffled channels in a 10-foot wide concrete flume.
    link
    Comparison of the novel D-Cylinder and standard Denil fish ladders
    Scientist standing in water inside a flume at the Conte Lab's fish passage complex
    link
    Aaron Heisey and EESC colleagues enter the east flume in the Conte Lab's Fish Passage Complex after the conclusion of a study trial to recover adult white suckers
    3 men hold a 9 foot tall wood frame upright in a parking lot
    link
    Constructing a Denil fishway baffle
    Two men standing next to a steel I-beam structure in a 10-foot wide concrete flume.
    link
    Steel support structure installed for fish ladder experiment
    Aerial photo of a laboratory campus consisting of 5 main buildings surrounded by trees and located between a canal and a rive
    link
    Aerial photo of the USGS Conte Research Laboratory
    Two men plant a pollinator garden
    link
    Planting the pollinator garden at the Conte Lab
    Man works sluice pipe in to the tank of a fish transport truck
    link
    Collecting shad for study at Holyoke fish lift
    Water runs through a screen and discharged from a 4-foot opening in a 20-foot concrete flume located in a large building.
    link
    Palisade study trials in the Fish Passage Complex with American shad
    Two men wearing waders drag a net between them to herd fish into a concrete channel.
    link
    Seining fish into the Burroughs Pond following the first shad trial
    Man stands on grating above a watered flume. Below, American shad school in the pool.
    link
    The first shad trial in the Palisade Entrance is complete
    Man wearing waders carries live American shad; shad has been implanted with PIT tag in dorsal fin.
    link
    Tagging and measuring American shad for the Palisade fishway study
    Man uses pliers to secure solenoid assembly to instrument housing on the back of a fish transport truck.
    link
    Adjustments to the O2 delivery system on Conte's fish truck
    Two stories of scaffolding assembled with four solar panels on top, facing south.
    link
    Solar Panel Installation
    3 men pose in front of a 23 foot long boat sitting on a trailer adjacent to a garage
    link
    Final preparations for the 2022 Delaware River American shad study
    Man kneels next to the carcass of a 7.5 ft long Atlantic Sturgeon.
    link
    Atlantic sturgeon recovered for necropsy
    Alex Haro clearing flume during lamprey study
    link
    Alex Haro clearing flume during lamprey light study
    From the banks of a drained 500 ft wide canal with substation in the background and a 4 foot trap sitting in 10 foot wide riv
    link
    Juvenile lamprey collection in the power canal
  • News
    link

    USGS research helps American shad find their way

    Science takes time.

    Read Article

*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government