Here in the South our large impoundments stratify once a year caused by two distinct thermal layers created by our mild winter and summer seasons. In more northern latitudes harsh winters cause most lake surfaces to freeze causing “turn-over” twice annually. It’s all about the density and quantity of this water storage which consists of dense cold water and less dense warm water created by seasonal air temperatures. In the South during the fall most impoundments experience turbid and murky flows exiting the penstocks. As the days get shorter and the nights get cooler this creates a cool dense layer that forms on the lake surface displacing warmer less dense summer layers which causes a stirring effect within the water column. Most dams were designed for maximize hydrostatic pressure by locating their outflow gate or penstocks deep at the base of the dam structure where this great force of water will pump through turbines during a water release to generate power to meet peak power demands.
What does this mean for the angler downstream? Because of these murky River conditions visibility is limited for the trout to see your fly. Anglers should use one or two hook sizes larger then usual and fish more methodically and thorough so fish are sure to see your offering.
This is published(circulated) in The Angler local north Ga magazine, threeTU chapters, Ga Women’s Fly Fishing Club and Atlanta Flyfishing Club newsletters