Sediment Monitoring Network - Background
The Benchmark Sediment Monitoring Program collects weekly suspended sediment samples at a selected set of Illinois rivers and streams. When the sample is collected the exact date, time, and stream stage are recorded representing an instant in time. Sediment samples are collected by local private citizen scientists trained by ISWS staff. Approximately every six weeks, calibration cross section samples or particle size data are collected at each location by Water Survey personnel, who then transport all samples to the ISWS Sediment Laboratory in Champaign for analysis.
The ISWS Sediment Laboratory determines suspended sediment concentrations or suspended sediment particle sizes within each sample.
Using the instantaneous date, time, and water stage information, water discharge data (collected at the same sites via USGS streamgages) and the suspended sediment concentration are used to calculate the instantaneous sediment load (in tons per day).
The Illinois State Water Survey has long been at the forefront of researching and monitoring sediment transport in Illinois waterways. The Water Survey initiated the Benchmark Sediment Monitoring Program (BSMP) in water year 1981 to develop a long-term database of suspended sediment transport. A long-term database such as this can be used to:
- Determine long-term trends in sediment transport in Illinois
- Estimate sediment loads for unmonitored streams
- Evaluate the effectiveness of watershed management programs
- Identify watersheds with high soil erosion and sediment delivery rates
The 1984 Illinois State Water Plan Task Force identified erosion and sediment control as the number one water resources issue for Illinois waterways. The 1984 plan stated that "excessive soil erosion on 9.6 million acres of Illinois farmland is threatening their productive capacity, degrading water quality, accelerating eutrophication of reservoirs, silting of streams, and degrading fish and wildlife habitat." (Illinois State Water Plan Task Force 1984) The Integrated Management Plan for the Illinois River Watershed (1997) still recognized the need for management to reduce erosion and sedimentation in the Illinois River Basin.
The Monitoring Program currently consists of fifteen sampling sites located throughout Illinois. Fourteen of the fifteen active sampling stations are located at U.S. Geological Survey (USGS) streamgaging stations. The USGS furnishes discharge rating tables for these stations. One station, #513 Cache River at Ullin, is an ISWS streamgaging station. This station discharge rating table is developed by the ISWS. Station information is available about these sampling sites.
Since the inception of the program, over 25,000 suspended sediment samples have been analyzed for the program monitoring sites creating a substantial database of sediment transport for Illinois waterways.