ISWS provides year-round sediment and nutrient monitoring for nine subwatersheds in Illinois to help the Illinois Department of Natural Resources evaluate the effectiveness of the Conservation Reserve Enhancement Program (CREP). Monitoring began in 1999 with five subwatersheds of the Illinois River Basin and was expanded in 2013 to include four subwatersheds in the Kaskaskia River Basin.
Monitoring includes collecting frequent water quality samples and discharge measurements, which are used to calculate annual loads and create watershed models. Each site is visited weekly and during storm events throughout the year to collect measurements and samples across seasonal and surface water stage variations.
Monitoring Areas
Illinois River Watershed
The Illinois River-CREP monitoring stations are located in west-central Illinois. Two stations are in the Sangamon River watershed in Cass County within the Jim Edgar Panther Creek State Fish and Wildlife Area. Three stations are in the Spoon River watershed in Knox County near Appleton and Maquon.
Monitored Subwatersheds
| Station | Name | Drainage Area (sq. mi) |
|---|---|---|
| 201 | Panther Creek | 16.5 |
| 202 | Cox Creek | 12.0 |
| 301 | Court Creek | 66.4 |
| 302 | North Creek | 26.0 |
| 303 | Haw Creek | 55.2 |
Station Map
Kaskaskia River Watershed
The Kaskaskia-CREP monitoring stations are in central/southern Illinois near Carlyle Lake. Two stations are south of the lake: Lost Creek, near Huey, and North Fork Kaskaskia, near Vernon. Hurricane Creek, near Bingham, and East Fork Shoal, near Witt, are north of Carlyle Lake.
Monitored Subwatersheds
| Station | Name | Drainage Area (sq. mi) |
|---|---|---|
| 402 | Lost Creek | 38.0 |
| 403 | North Fork Kaskaskia | 35.5 |
| 404 | Hurricane Creek | 27.7 |
| 405 | East Fork Shoal Creek | 30.9 |
Station Map
Stream Gauging & Auto Sampling Equipment
The Illinois River-CREP monitoring stations are equipped with a datalogger, pressure transducer, and storage module. A battery and an automatic water pump sampler are required to operate the monitoring equipment.
The Kaskaskia-CREP monitoring stations are equipped with a datalogger, surface water radar, modem, antenna, solar panel to recharge the batteries powering the monitoring equipment, and an automatic water pump sampler.
Water Quality Sampling
Baseflow nutrient and suspended sediment samples are collected weekly. Each station’s datalogger is programmed to enable the automatic water pump to collect samples when the stream stage is above a predetermined elevation.
During storm events, samples are collected more frequently and at specific points along the hydrograph. This allows more samples to be collected during critical periods (rises, peaks, and falls) in the hydrograph, as the stage (water level) responds to runoff from precipitation in the study area. Most nutrient and sediment concentrations are highest when the stage is rising quickly (before the peak in each hydrograph); however, nitrate concentrations are diluted as stage increases.
Each watershed has unique characteristics that affect its reaction to a rainfall event — the timing of runoff, stream stage, and sediment and nutrient loads. To account for this, each station has its own customized sampling parameters, which can be modified to achieve optimal sample distribution and adjusted seasonally to reflect changing baseline conditions.
Nutrient Analytes
ISWS staff in the Health and Environmental Applications Laboratory analyze our samples for nitrogen and phosphorus analytes.
Nitrogen analytes
- Total Kjeldahl Nitrogen (TKN)
- Nitrate as Nitrogen (NO3-N)
- Ammonium as Nitrogen (NH4-N)
Phosphorus analytes
- Orthophosphate (oPO4-P)
- Total Dissolved Phosphorus (TP-Dis)
- Total Phosphorus (TP)
Sediment
The Sediment Materials Laboratory assesses:
- Suspended Sediment Concentration
- Suspended Sediment Particle Size
Rainfall Data Collection
Pluvio raingages at Illinois River Watershed sites are equipped with a datalogger and a solar panel. Several raingages are located in each subwatershed.
Measuring Stream Discharge
ISWS staff use a Sontek M9 Acoustic Doppler Current Profiler (ADCP) to collect discharge measurements under medium- to high-flow stream conditions. We use Sontek Flowtracker for low-flow measurements when the stream is wadeable.
Annual Reporting & Publications
Unpublished Annual Reporting
Listing of Illinois CREP Annual Reports that include Illinois and Kaskaskia river watershed monitoring data.
| Illinois CREP Annual Reports | Illinois River Watershed | Kaskaskia River Watershed |
|---|---|---|
| 2021 Illinois CREP Report | n/a | n/a |
| 2020 Illinois CREP Report | n/a | n/a |
| 2019 Illinois CREP Report | n/a | n/a |
| 2018 Illinois CREP Report | n/a | n/a |
| 2017 Illinois CREP Report | Appendix B | Appendix C |
| 2016 Illinois CREP Report | Appendix B | Appendix C |
| 2015 Illinois CREP Report | Appendix C | Appendix D |
| 2014 Illinois CREP Report | Appendix C | Appendix D |