Environmental and Water Quality Operational Studies. Riverine Influences on the Water Quality Characteristics of West Point Lake

The transport of dissolved and particulate nutrients, metals, and organic materials from watershed to lake plays a common role in determining lake water quality. For lakes which receive a majority of their loads from a single, large tributary, processes occurring in headwater areas may act to modify the ultimate impacts of these loads. These processes include sedimentation, phytoplankton production, microbial degradation, and oxidation-reduction reactions. This will be particularly true in stratified lakes and reservoirs which exhibit density currents. Studies conducted at West Point Lake, Georgia, during October 1980 and July 1981 employed tracer dye to allow repetitive sampling of parcels of inflowing Chattahoochee River water as they entered and progressed through the upstream portion of the reservoir. Inflows during October 1980 were vertically well mixed, while those in July 1981 entered as an interflow. A well-defined plunge point was observed in the lake's headwater area during the July 1981 study. Time-related changes in suspended solids, chlorophyll, nutrient, and meal concentration were observed. Changes in dissolved oxygen during the July 1981 study resulted from a reduction in photosynthetic productivity and the confinement of river water to intermediate depths. Increases in management concentration and dye distribution suggested the entrainment of hypolimnetic water by the riverine layer and the mixing of riverine water into the epilimnion.