Data from five northeast Georgia trout streams revealed significant alteration of ambient temperatures by impoundments. A 7.3 ha impoundment releasing water at 3.9 m warmed Anderson Creek a mean 2.2 C during August 1973 and reduced diurnal temperature variation by two-thirds. Surfacerelease impoundments on Bean Creek and Chickamauga Creek warmed ambient temperatures a mean 4.2 C and 3.8 C, respectively, dUring the summer of 1974. Diurnal fluctuations were increased in these two streams. A 21 ha surface release impoundment on Smith Creek warmed ambient stream temperatures a mean 3.6 C during the summer of1973 in spite of efforts to release water through the drain valve at 18 m below the surface. A multi-level release structure on Taylor Creek designed to closely duplicate ambient mean daily temperatures was not properly adjusted and elevated temperatures a mean 4.3 C during a three month period.