The Illinois Conservation Reserve Enhancement Program (CREP) is a state, federal and local partnership that was designed to restore and protect environmentally sensitive croplands in the Illinois and Kaskaskia River watersheds. Reducing sediment and nutrient loadings to both Illinois and Kaskaskia Rivers by 20 and 10 percent, respectively, are among CREP’s main goals, which consequently help towards decreasing the hypoxic zone in the Gulf of Mexico. To assess the effectiveness of CREP towards achieving its water quality goals, hydrologic and water quality monitoring has been conducted in a total of seven subwatersheds of Spoon and Sangamon River, which are major tributaries of the Illinois River. In five of the seven watersheds, data collection began in 1998 and it includes precipitation, flow, suspended sediment, and different species of nitrogen and phosphorus. The water quality impacts of CREP in these watersheds were evaluated using data analysis and modeling. Sediment and nutrient fluxes were estimated through modeling the relationships between constituent concentrations and discharges. To perform inter-year comparisons that removes the impact of sampling frequency, annual mean concentrations were calculated. Flow-normalized fluxes of sediment and nutrients were computed to detect water quality trends not influenced by annual flow variability, thereby providing more insight into the effectiveness of the conservation efforts in the study watersheds. From water year 2000 to 2016, sediment, nitrate-nitrogen and total phosphorus fluxes show decreasing trends in the study watersheds with reduction ranges of 27-44%, 22-44% and 7-51%, respectively. During 2011-2016 period, on average, the annual sediment, nitrate-nitrogen, and total phosphorus yields reduced by 3.3 metric tons/hectare (ha), 15.1 kg/ha and 2.4kg/ha, respectively. Results indicated the positive impact of CREP enrollments in reducing sediment and nutrient fluxes out of the study watersheds. CREP's effectiveness could be further improved through optimal selection and placement of the conservation practices in the watersheds.
Elias Getahun– Research Hydrologist, Illinois State Water Survey at Prairie Research Institute, University of Illinois Urbana-Champaign, Champaign, Illinois
Illinois State Water Survey at Prairie Research Institute, University of Illinois Urbana-Champaign
Dr. Elias Getahun is a research hydrologist with Illinois State Water Survey at Prairie Research Institute, University of Illinois Urbana-Champaign. He received his PhD in civil engineering from Southern Illinois University. Dr. Getahun (Bekele) has more than 10 years of experience in water resources systems analysis, watershed modeling and decision support systems for non-point source pollution control. He has published his research work in peer-reviewed journals, technical reports and conference proceedings.