In this photo provided by Terry Gunn, Lehman Beardsley, left, and Gunn, who guides fishing trips, pose with a rainbow trout at Lees Ferry near Marble Canyon, Ariz., Nov 7, 1987. As Lake Powell reservoir just upstream declines, it sends warmer water with less oxygen into the river below the dam. Should that water reach 73 degrees, Gunn said his family's guide service may start calling off afternoon trips. (Courtesy of Terry Gunn via AP)