Limnological Characteristics of Lake Houston - Sediment, Nutrient, and Hydrologic Interactions

Lake Houston, a man-made lake, is used as a water supply source for the City of Houston, and for recreational purposes. Rapid urbanization in the Lake Houston watershed has increased the pollutant loads into the lake. The lake is highly turbid and it has a very high nutrient concentration. The shallowness of the lake and the frequent storms in the area keep the lake well mixed. Storm flows and turbidity inhibit large growths of algae by washing out the algae and allowing little light to penetrate the water column. A water balance performed on the lake allowed for the development of a stage-discharge relationship. The sediment and nutrient mass balance showed that most pollutants are retained in the lake. A hydrodynamic simulation of the lake showed a storm-wave travel time of about two hours. Actual data for six storms shows that most of the time the lake reaches a high stage before the tributaries. Detention time for Lake Houston is about 40 days, very short compared to many other lakes. Two empirically derived equations that describe the major lake processes were developed for Lake Houston using the Stastical Analysis System (SAS) computer package. The relationships indicate the amount of algae present in the lake and their potential for growth. Chlorophyll a, a measure of algal biomass, is modeled as a function of flow rate and turbidity. Algal productivity rate is assumed to be a function of chlorophyll a and water temperature.