Impacts of Assimilative Capacity of Reservoirs
HARC Research finalized for TCEQ’s Galveston Bay Estuary Program
Lake Livingston, a multipurpose reservoir, is situated amongst mixed pine and hardwood forests in southeast Texas. In 1969 the reservoir was created when the Lake Livingston Dam was constructed. Due to impoundment, the Trinity River was divided into two sections; the Upper and Lower Trinity.
The goal of the Impacts of Assimilative Capacity of Reservoirs on Coastal Inflows project was to assess assimilative capacity of the Lake Livingston reservoir and related impacts on freshwater inflows to the Galveston Bay estuary. This project sampled inflow from the Upper Trinity to the north and outflow from the Lower Trinity south of the Lake Livingston Dam to quantify nutrient and suspended sediment concentrations, deployed a GPS drifter to track flow patterns and currents, and collected depth profiles to determine degree of stratification.
Water quality sampling was conducted during six sampling events between May 2016 and August 2018. Samples were collected during base, moderate, and high flow conditions. The sampling events do not show elevated nutrient or sediment concentrations leaving the lake during high or base flow conditions. This could be due to a lack of samples collected during high flow events, time between sample collection, or turnover patterns in the lake. Most suspended sediments, phosphorus, and total nitrogen sample events resulted in a decreasing pattern from north to south with maximum concentrations detected at the Trinity River Riverside - North site.
These results suggest that the Lake Livingston Reservoir, an artificial impoundment, is a nutrient and sediment sink.