Limnological characteristics, nutrient loading and limitation, and potential sources of taste and odor problems in Standley Lake, Colorado

Abstract

Standley Lake is a reservoir that provides water to several suburban cities in Jefferson County, northwest of Denver, Colorado. In 1988, a taste and odor problem developed in water supplied from the lake. In 1989, a study was begun to determine the nutrient availability in the lake, the potential nutrient limitation to algal biomass, and the occurrence and potential sources of compounds that cause taste and odor problems in water withdrawn from the lake. Physical, chemical, and biological water-quality data were collected during June 1989 through October 1990 from sites in the lake, its primary inflows, and its outflow. Standley Lake was thermally stratified from June through September each year of the study and was well mixed during October-December and March-May. Nutrient concentrations were low in the photic zone. Total nitrogen generally was less than 0.3 milligram per liter and total phosphorus always was less than 0.02 milligram per liter. Concentrations were higher in the hypolimnion, particularly during stratification. Maximum total nitrogen was at least 0.5 milligram per liter during both years of the study, and maximum total phosphorus exceeded 0.05 milligram per liter during both years. Phytoplankton biovolume and chlorophyll a concentration were variable throughout the open-water season. The maximum chlorophyll a concentration was 6.1 micrograms per liter.