Monitoring Water Quality to Demonstrate the Impact of Agricultural Best Management Practices along a Defined Segment of Eagle Creek

Abstract

Several parameters related to water quality were monitored systematically during two years to assess the impact of recently implemented agricultural Best Management Practices (BMPs) along a defined segment of Eagle Creek in southern Lyon County (KS). Earlier studies, conducted by Kansas Department of Health and Environment (KDHE), identified several impairments to water-quality in Eagle Creek. Previously cited impairments included nutrient concentrations (nitrogen and phosphate containing compounds) exceeding Environmental Protection Agency (EPA) recommendations and dissolved oxygen concentration chronically below the EPA’s threshold (5-mg/L) for the survival of most aquatic organisms. Measurements in the current study included in situ and others were made on samples returned to the laboratory. Seasonal monitoring at base-flow conditions was done in fall, spring and summer. Three additional sets of data were collected during storm-event conditions. Storm-event sampling included additional sampling points to identify and/or isolate sources of nutrients carried into the stream as run-off from the surrounding agricultural operations. First-flush buckets were used to identify contributions from the cropland conservation buffer, before the runoff entered the Creek. Most of the parameters exhibited a normal seasonal variation for base-flow measurements. During storm-events, turbidity, conductivity, nitrite, and nitrate concentrations were higher in the first-flush buckets than in water entering the Creek as runoff. The trend for dissolved oxygen concentration shows sufficient increase so that the concentration is above EPA’s 5-mg/L threshold for aquatic life. The agricultural BMPs now utilized are improving the quality of the water by allowing sedimentation to occur before runoff. This not only reduces the amount of sediment entering the Creek, but it helps reduce nutrient flux into the stream since some nutrients tend to adsorb to the sediments. Monitoring of parameters should continue to provide confirmation that the agricultural BMPs have improved the water quality of Eagle Creek.