Modeling pit lake water column stability using Ce-Qual-W2

Field measurements of temperature, conductivity, and TDS in an acidic pit lake in southeast Tennessee show that the water column of the lake is currently density stratified. The relative depth of the pit is an intermediate value suggesting that while potentially stable, based on bathymetry alone, the pit’s water column could mix. The potential for the pit’s water column to turn over is a concern because mixing of the shallow low TDS water and the deep high TDS water could potentially degrade the water quality downstream. Water quality, temperature and bathymetric data were used with meteorological observations to develop a limnologic model of the pit using the Ce-Qual-W2 (v.3.0). A series of model simulations were designed to test the long-term stability of the pit’s chemical stratification under changing temperatures, storm events, and water quality (TDS) conditions.