Small Reservoir Impacts on Stream Water Quality in Agricultural, Developed, and Forested Watersheds: Georgia Piedmont, USA

Small reservoirs are prevalent landscape features and an important component of headwater hydrology. Tens of thousands of small ponds, most less than a hectare, were constructed over the past century within the United States. While remote-sensing and geographic-mapping technologies assist in quantifying these features, their influence on water quality is less well understood. This study reports the results of a year-long physicochemical study of nine ponds (0.152.17 ha) within the Oconee and Broad River watersheds in the Georgia Piedmont. Study sites were selected along an urban-to-rural gradient (i.e., three each of developed, agricultural, and forested) and were sampled monthly for pond discharge as well as inflow and outflow water-quality parameters (pH, temperature, specific conductance, dissolved oxygen, turbidity, alkalinity, total phosphorus, total nitrogen, nitrate, ammonium). While not representative of all ponds, this study provides reference conditions for pond water quality and examines downstream impacts within divergent land uses in the Georgia Piedmont. Results indicate small reservoirs have a significant impact on stream water quality and that this impact varies significantly based on the type of dam structure (top-release vs. bottom release).