Nutrient analysis of sediment interstitial water of the Prairie Creek Reservoir, Indiana

Prairie Creek Reservoir in east central Indiana serves as a secondary water supply for the city of Muncie and is also used as a recreational facility. Due to water quality concerns, this study was conducted to characterize spatial and temporal variability of physical and chemical parameters, specifically nutrients, in the sediment interstitial (pore) water at three reservoir locations. The pH, temperature, specific conductivity, ammonia, nitrates, total nitrogen, orthophosphates and total phosphorus, were monitored twice per month from June through September 2006. Spatial variations in the sediment interstitial water were evident for all water quality parameters, except phosphorus and orthophosphates. Variability in temporal nutrient concentrations in pore water was most likely affected by decomposition of organic matter and presence of anoxic conditions in the overlying water. The results showed high internal nutrient loading, especially from phosphorus, in the sediment interstitial water. Under anoxic conditions, these excessive nutrient concentrations within the sediment can be released into the water column and exacerbate eutrophication of the reservoir. This study provides useful assessment of internal nutrient loading in the Prairie Creek Reservoir sediment that should be considered in the implementation of land management strategies and future land development practices in the reservoir watershed.