Tell me why smallmouth bass are becoming a problem. So if we look to the Upper Basin, so parts of the river in Colorado and Utah, smallmouth bass have been a problem for years. They’ve been stocked throughout West as a recreational fishery, and they’re a ton of fun to catch, but they often have detrimental consequences for native fish and native ecosystems…. but historically the section of the Colorado River between Lake Powell and Lake Mead has been insulated from that. Because Glen Canyon Dam served as a barrier.