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
Downstream fish passage guide walls: A hydraulic scale model analysis
Sensitivity of the downward to sweeping velocity ratio to the bypass flow percentage along a guide wall for downstream fish passage
A computational fluid dynamics modeling study of guide walls for downstream fish passage
Derivation and application of the energy dissipation factor in the design of fishways
Non-USGS Publications**
**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.
Fish Passage Design and Analysis at the S.O. Conte Research Laboratory

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). ApproximatelAuthorsKevin Mulligan, Alexander J. Haro, Brett Towler, Bryan Sojkowski, John NoreikaDownstream 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 walAuthorsKevin Mulligan, Brett Towler, Alexander J. Haro, David P. AhlfeldSensitivity 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 velocityAuthorsKevin Mulligan, Brett Towler, Alexander J. Haro, David P. AhlfeldA 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 entrainmentAuthorsKevin Mulligan, Brett Towler, Alexander J. Haro, David P. AhlfeldDerivation 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 EDFAuthorsBrett Towler, Kevin Mulligan, Alexander J. HaroNon-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
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... - Multimedia
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
- News
*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