Matthew Kliegl felt a bit like a fish out of water when his master’s degree led him to study fish and their swimming behaviors. As a civil and environmental engineering graduate student in the Structures, Mechanics, and Materials program, Kliegl embraced the opportunity to contribute to IIHR—Hydroscience and Engineering’s (IIHR) long legacy of fish passage research. Through his studies, he's helping to understand the movement of fish at the Melvin Price Lock and Dam on the Mississippi River.
His research supports a U.S. Army Corps of Engineers (USACE)-funded initiative to establish the National Information Collaboration on Ecohydraulics program, which aims to improve understanding of the ecological impacts of human-caused changes to major U.S. water bodies. Kliegl is developing a computational fluid dynamics model to simulate the effectiveness of different fish passage structures and evaluate their performance to make them safer for migrating fish species.
“We’ve been developing a model that describes the hydrodynamics of the water around the dam,” said Kliegl. “Once we understand those dynamics, we can use that information to evaluate how the fish might move through different fish passage alternatives.”
The Mississippi River’s lock and dam system allows the naturally impassible river to be navigable, enabling a pathway for commerce and goods to travel through. However, it also creates a physical barrier that restricts fish movement, disconnecting habitats. Fish passage devices work to reconnect the river, but the effectiveness of these devices is not yet well understood.
“This project is on the forefront of fish passage research,” said Kliegl. “It's one of the first times this type of modeling has been done on the Mississippi. A new fish passage device is being built at Lock and Dam 22, but this work at Melvin Price is breaking new ground.”
To evaluate design alternatives, Kliegl developed a computational fluid dynamics model to test different options. His goal is to find a design that accommodates the river’s diverse fish species, including lake sturgeon, blue catfish, and skipjack herring—each with different swim speeds and agility.
USACE provides design criteria that enable safe fish passage for all species, which they share with Kliegl and his co-advisors, Larry Weber, director of IIHR, and Nate Young, research engineer. Velocity and depth parameters were also given by USACE to ensure that the majority of fish species could pass through the dam with low levels of stress or mortality.
“We’re testing many options and variables to see what’s feasible. Varying things like length, slope, longitudinal and traverse slopes, how many boulders, the configuration of them — you name it,” said Kliegl, “We’re on our nineteenth model iteration now, trying to find a design that meets all the USACE parameters.”
To validate the model, Kliegl and his team visited the Melvin Price Dam to collect field data. They captured water surface elevations upstream and downstream, cross sections of the spillway to measure currents, and gathered depth measurements. The observed data supported the model results, helping to ensure the accuracy and reliability of the model.
“Using what we learn modeling and eventually implementing this fish passage structure at this dam, we can ideally use this design in other areas and hopefully see fish populations rise again,” said Kliegl. “It’s important from not just an ecological view, but economic as well. There’s a large economy built into river towns with fish hatcheries.”
Kliegl is on track to graduate in December 2025. Upon graduation, he’s considering private consulting for structural engineering, hydraulic engineering, or a combination of both.
“It’s nice to have options,” said Kliegl. “Either way, I know I’ll be doing something I really enjoy.”
Reflecting on his experience, Kliegl feels fortunate to be a part of such a great community of people at IIHR, especially his advisors and other team members who have helped guide and support his work.
