National Water-Quality Assessment Program
Upper Illinois River Basin
National Water-Quality Assessment Program
Upper Illinois River Basin
The objectives of the basic fixed-site network are to determine the occurrence and distribution of chemical constituents in the water column at selected stream sites. Sites are selected based on the combination of natural environmental setting (physiography, bedrock geology, and surficial deposits) and land use in the drainage basins. Intensive fixed sites are a subset of the basic fixed sites where more frequent sampling is conducted for additional constituents. The fixed site network is made of sites classified as integrator and indicator sites. Some of these sites are also part of a National Trends Network.
Surface-water-quality sampling began at the fixed sites in March 1999 and the high intensity phase sampling ended in August, 2001. Ecological sampling at all eight sites was complete in August 2001. Three trends sites ( Sugar Creek at Milford, Salt Creek at Western Springs, and Des Plaines River at Riverside) are sampled monthly or every other month and ecological sampling is done yearly.
Streams in the UIRB have been the focus of ecological investigations since before the turn-of-the-century. During the UIRB High Intensity Phase (HIP), three ecological activities were conducted: bed sediment and tissue (BS&T) sampling, aquatic community sampling, and describing habitat and geomorphology. Bed sediment and tissue sampling was completed earlier in the HIP. Two reports examining the combined BS&T results from the Upper and Lower Illinois Rivers are in review. Ecological sampling was conducted at eight fixed sites during the HIP. Three reaches were sampled at each of two stations, and multiple-year sampling was conducted at two stations. Basin and segment habitat data were compiled. During the next HIP, multi-reach sampling will be done at Sugar Creek near Milford.
The three trends sites will all be sampled 8 times during FY03 for water-column analysis. Sampling will be during the even-numbered months (6) with additional samples in May and July. These 8 samples will be analyzed for nutrients, suspended sediment and pesticides. At the 2 Chicago-area Trends sites only, two additional sampling months are added in November and January, but only for nutrients and suspended sediment. The urban land-use Trends sites may have different nutrient cycles than the agricultural settings in the basin.
Sampling will continue at three trends sites at the recommended frequency and analytical strategy. Salt Creek will have continuous real-time monitoring for specific conductance, temperature, dissolved oxygen and pH funded through a cooperative program the district has with the Illinois EPA.
A special study of stream water-quality degradation along an urban land use gradient (LUG) was conducted in the Fox and Des Plaines watersheds (1999-2001). Analytical results are complete and interpretation and report writing is being completed. Fish, algae and macroinvertebrates were collected at the three trend sites summer 2002 during the index period.
The NAWQA Program is studying several water-quality issues associated with urban and agricultural watersheds.
As the Chicago metropolitan area expands, much of the surrounding agricultural land is being converted to urban use. This is of increasing importance due to new water supplies being developed in these shallow aquifers because (1) Lake Michigan water is fully appropriated, (2) bedrock aquifers are over-used, (3) upwelling of brine in bedrock aquifers, and (4) continued westward urban expansion.
Four ground-water networks were sampled during the first HIP. Two major aquifer surveys sampled existing domestic and public-supply wells. The first (uirbsus2) is a network of wells in the sand and gravel aquifer underlying part of the Kankakee River Basin in Indiana and Illinois. The second major aquifer survey (uirbsus1) is a network of wells in the shallow sand and gravel aquifer that are highly susceptible to contamination from land surface. In both areas, land use historically was farming. In uirbsus1, urban influences will eventually be the predominant cause of anthropogenic contamination.
The two land-use surveys of recently recharged ground water sampled during the first HIP were similarly located. The first (uirbluscr1) is an agricultural land-use survey nested within uirbsus2 in Indiana and Illinois. The urban land-use survey (uirblusrc1) is nested within uirbsus1 in northeastern Illinois and southern Wisconsin in residential-commercial areas.
Return to the Upper Illinois River Basin page