Monday June 13, 2022
The Aspen Times —
As climate change continues to shrink the nation’s second-largest reservoir, water managers are scrambling to prevent the release of an invasive fish into the Grand Canyon.
Smallmouth bass, a voracious predator and popular game fish, have been introduced into reservoirs throughout the Colorado River basin, including Lake Powell. The looming problem now is that as lake levels drop to historically low levels, the invasive fish are likely to escape beyond Glen Canyon Dam, threatening endangered fish in the canyon, whose populations have rebounded in recent years.
Smallmouth bass are a warm-water-loving species, hanging out in the top part of the water column, which is warmed by the sun. Until recently, the intakes for turbines at Glen Canyon Dam had been lower in the water column, where colder temperatures kept the fish away. But as the lake level falls, the warmer water band containing the smallmouth bass is sinking closer to the intakes, making it more likely that they will pass through the dam to the river below.