Forest cuttings raise temperatures of small streams in the southern Appalachians

Stream temperatures were measured during six forest-cutting treatments on small (23to 70-acre) watersheds in the southern Appalachian Mountains. Where forest trees and all understory vegetation were completely cut, maximum stream temperatures in summer increased from the normal 66°F to 73° or more. Some extreme treatments raised temperatures more than '"12° above normal. Where streambank vegetation was uncut or had regrown, summer maximums remained unchanged or declined from temperatures measured under uncut mature hardwood forest. Increases in stream temperature were judged to degrade water quality and constitute thermal pollution because, after each clearcut, water temperatures exceeded optimum levels for