About the Benchmark Sediment Monitoring Program
The Benchmark Sediment Monitoring Program collects weekly suspended sediment samples at a selected set of Illinois rivers
and streams. Sediment collection samples are gathered by local private citizens trained by ISWS staff. Approximately every
six weeks, calibration cross section samples and particle size data are collected at each location by Water Survey personnel,
who then transport all samples to the water survey Sediment Laboratory in Champaign for analysis.
The Sediment Laboratory determines suspended sediment concentrations and suspended sediment particle sizes within each sample.
Suspended sediment sample concentrations are paired with automated instantaneous water discharge data (collected at the same sites via USGS
gages) for calculation of 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 a Benchmark Sediment Monitoring Program in 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 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 SWS streamgaging station. This station discharge rating table is
developed by the SWS. Station information is available about these sampling sites.
Since the inception of the program, over 23,000 suspended sediment samples have been analyzed for
the program monitoring sites creating a substantial database of sediment transport for Illinois waterways.
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