BULLHEAD CITY — Twenty volunteers from Bullhead City and the Phoenix area joined the City of Bullhead City Pest Abatement Program, Arizona Game and Fish Department and Trout Unlimited on May 2 to help construct nearly 200 artificial river reef structures that will be deployed in the Colorado River.
The volunteer-built structures are designed to create complex underwater habitat for fish and other aquatic organisms by providing shelter, feeding areas and relief from strong currents. The project supports ongoing efforts to improve habitat for both stocked and native fish species while helping reduce nuisance aquatic insect populations that affect riverfront residents.
The event marked the latest phase of a habitat enhancement initiative that began as a local effort to address challenges in the Colorado River below Davis Dam and has since contributed to peer-reviewed scientific research.
“This project is a first-of-its-kind, large-scale initiative to increase benthic habitat complexity in a major U.S. river through construction of an artificial river reef that enhances river ecosystem function and promotes long-term habitat restoration for native and sport fish,” said Dr. Michael Cavallaro, Bullhead City Pest Abatement Manager.
In 2024, Cavallaro and co-author David Schumann published research in the scientific journal River Research and Applications examining the effectiveness of artificial river reef structures in the Colorado River below Davis Dam. The study found that properly placed reef structures can remain functional for years in a river system affected by hydropeaking, the rapid changes in water flow caused by hydroelectric dam operations.
The research also identified river-bottom conditions that improve the long-term performance of the structures, providing practical guidance for future habitat enhancement projects.
For Bullhead City, the work has direct local benefits.
The Colorado River below Davis Dam supports seasonal stockings of Rainbow Trout as part of the City’s aquatic insect management program. Trout prey on black flies and net-spinning caddisflies, helping reduce nuisance insect populations that can impact the quality of life of riverfront residents and visitors.
“Fundamentally, we’re restoring habitat complexity by installing engineered concrete structures in the Lower Colorado River,” Cavallaro said. “The Bullhead City Pest Abatement District stocks tens of thousands of Rainbow Trout each year. These structures create flow refugia and foraging zones that improve survival and retention of stocked and resident insectivorous fish species, increasing predation pressure on nuisance aquatic insects.”
The project also highlights how local partnerships can contribute to broader environmental solutions. While the volunteer event focused on constructing habitat structures, the effort is part of a larger initiative exploring ways to improve fish habitat in rivers altered by dams and changing flow conditions.
The City of Bullhead City thanked the volunteers, Arizona Game and Fish Department, Trout Unlimited and project partners whose time and expertise helped make the event possible. Their efforts will help expand fish habitat in the Colorado River while supporting a project that combines community involvement, environmental stewardship and scientific research.
More information about the research can be found in Cavallaro and Schumann’s 2024 study, Utility of Artificial River Reef Structures to Enhance Fish Habitat Below a Hydropeaking Dam, published in River Research and Applications. The full article can be reviewed on Bullhead City’s website at bullheadcityaz.gov/living-in-bullhead-city/pest-abatement/
