In 2024, managers deliberately cooled the Colorado River to protect the Grand Canyon from invasive smallmouth bass. 2 years later, no bass recruitment had been detected, but the effort cost $19.1 million in replacement power

Managing a major river is often a balancing act between protecting ecosystems and maintaining essential infrastructure. At Glen Canyon Dam, officials took an unusual approach in 2024 by deliberately cooling part of the Colorado River to prevent invasive smallmouth bass from reproducing near the Grand Canyon.

The strategy appeared to work biologically. Monitoring detected no smallmouth bass recruitment in 2024, while preliminary results from 2025 also found none, although scientists conducted less field sampling. But the environmental measure came with a major energy cost: $19.1 million in replacement power in 2024 and another $6.5 million in 2025.