Corrected chlorophylladata were gathered for 17 small southeastern piedmont impoundments <648 ha (<1600 a) ranging in trophic state from mesotrophic to hypereutrophic. Working with the managerial concept that water-use impacts are more directly related to frequency of blooms than to mean seasonal values, regression equations were calculated to relate bloom frequency to seasonal mean chlorophyllaconcentrations. The relationship between bloom frequency (chlorophylla≥30 μg/L) and mean chlorophyllaconcentration in this study was very similar to that found for U.S. Army Corps of Engineers (COE) impoundments.