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changes in nitrate-N concentration and streamflow. Flow-weighted nitrate-N concentrations <br /> have been increasing during the study period at the Monticello station. <br /> Based on the first six years of monitoring, the Illinois State Water Survey has developed a <br /> model (Guo et al., 2002; Markus et al., 2003) to forecast nitrate-N concentrations in Lake <br /> Decatur using previous and current nitrate levels in the lake. This tool is valuable for <br /> management of the ion exchange facility operated by the City of Decatur. <br /> In order to best evaluate any ongoing and future lake and watershed management issues, <br /> continued monitoring is recommended. The additional data will enhance the baseline data <br /> established in the watershed and detect any changes or trends in nitrate-N levels in the watershed. <br /> PROJECT OBJECTIVES <br /> The main goal of this project is to collect reliable data throughout the Lake Decatur <br /> watershed for use by City of Decatur planners and resource managers to develop lake and <br /> watershed management alternatives based on scientific data. To accomplish this goal, the <br /> following objectives are outlined: <br /> 1. Continue to maintain and operate watershed monitoring stations. Figure 1 <br /> shows the stations being monitored in the Lake Decatur watershed. The Illinois State Water <br /> Survey will maintain the continuous stream recording equipment at Big/Long Creek (101) and <br /> Friends Creek(102) and the data records will be processed to determine continuous stream flows. <br /> The discharge data from the USGS station on the Sangamon River at Monticello (111) will be <br /> retrieved for this project. <br /> 2. Collect water sample data: Nitrate-N will continue to be sampled weekly and <br /> some storms at three stations: Big/Long Creek (101), Friends Creek (102), and Sangamon River <br /> at Monticello (111). This sampling schedule will provide the data needed to quantify the amount <br /> of nitrates being contributed to Lake Decatur from the watershed. The sample temperature and <br /> pH will be measured on-site using a portable field meter at all sites for all samples collected. <br /> Selected nutrients will be collected at one tributary station on a regular basis. All samples will be <br /> analyzed at the ISWS Analytical Chemistry and Technology Unit (ACTU). <br /> 3. Process and analyze annual data collection. The one-year of data will be <br /> processed for water discharge (flow), concentrations, and loading for the three watershed <br /> 2 <br />