Retention time and flow patterns in Lake Moultrie, South Carolina

A liquid dye tracer was injected into the inflow to Lake Moultrie, South Carolina, during high-flow conditions and again during low-flow conditions. Tracer concentrations were monitored at a network of fixed sampling stations in the lake to determine dispersion and transport characteristics in and through the lake. Wind-generated currents were the major factor in dispersing the tracer and controlling the flow patterns, with the advective flow of water through the lake a secondary contributing factor. During the high-flow test, most of the tracer was flushed through the lake in 12 days, which did not allow time for the tracer to fully disperse throughout the lake. During the low-flow test, most of the tracer remained in the lake for more than a of a month. After 16 days it was dispersed throughout the lake. Concentrations of tracer decreased by a factor of about 500 as the dye clouds passed through the lake. (USGS)