EFFECTS OF LAND USE ON WATER QUALITY AND NUTRIENT LOADING IN EAGLE CREEK WATERSHED, CENTRAL INDIANA, USA

The purpose of this research is to understand the effects of residential development on water quality and sediment loading in temperate watersheds. Watershed changes associated with development, such as the removal of groundwater and runoff buffer zones, changes in vegetation cover, changes in topography, and increases in bare soil cover and impervious surface cover, can cause increased nutrient loading to streams and lead to cultural eutrophication of impoundments. This study was conducted in Eagle Creek Watershed, a predominantly agricultural watershed which has experienced increased urbanization in recent years. Streams in Eagle Creek Watershed flow into Eagle Creek Reservoir, a drinking water resource of 80,000 Indianapolis residents. Understanding the source, quantity, type, mechanism, and delivery of nutrient loads to Eagle Creek Reservoir will provide critical data for long-term management. Therefore, a detailed land use, water quality comparison was completed in two sub-watersheds with discrete land use gradients, Fishback Creek and School Branch. The study examined the influences of land use on stream loading by measuring various in-stream physical and chemical parameters with respect to land use variation, seasonality, and flow regime. Results indicated that runoff generated from residentially developed lands uniquely influence loading rates to temperate low relief streams. Low correlation between discharge and nutrient loading, during high flow regime events, indicated land use as the primary control on variation to stream nutrient loading. In addition, high flow regime events were responsible for the majority of nutrient loading to watershed streams and thus to Eagle Creek Reservoir.