Phytoplankton Bloom Frequencies in a Population of Small Southeastern Impoundments

ABSTRACT

Corrected chlorophyll a data 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 chlorophyll a concentrations. The relationship between bloom frequency (chlorophyll a ≥30 μg/L) and mean chlorophyll a concentration in this study was very similar to that found for U.S. Army Corps of Engineers (COE) impoundments.

Based on this bloom frequency analysis, literature values, and experience, a mean growing season limit of ≤15 (μg/L of chlorophyll a is recommended for small southeastern piedmont water supply impoundments. For other water uses, a mean growing season chlorophyll a concentration of <25 μg/L is recommended to maintain a minimal aesthetic environment for viewing pleasure, safe swimming, and good fishing and boating.

Key Words:

• phytoplankton
• bloom
• southeastern
• piedmont
• chlorophyll
• impoundment
• lake
• reservoir