The NASQAN sampling sites for which data are published in this report are Wabash River at New Harmony, IN (03378500), Ohio River at Lock and Dam 53 near Grand Chain, IL (03612500),  Mississippi River at Clinton, IA (05420500), and Mississippi River at Thebes, IL (07022000).

The National Atmospheric Deposition Program/National Trends Network  (NADP/NTN) is a network of monitoring sites that provides continuous measurement and assessment of the chemical constituents in precipitation throughout the United States. As the lead Federal agency, the USGS works together with over 100 organizations to provide a long-term, spatial and temporal record of atmospheric deposition generated from this network of 250 precipitation-chemistry monitoring sites. The USGS supports 74 of these 250 sites. This long-term, nationally consistent monitoring program, coupled with ecosystem research, provides critical information toward a national scorecard to evaluate the effectiveness of ongoing and future regulations intended to reduce atmospheric emissions and subsequent impacts to the Nation's land and water resources. Reports and other information on the NADP/NTN Program, as well as data from the individual sites, may be accessed at http://bqs.usgs.gov/acidrain/.

In Illinois, atmospheric-deposition data are available for five stations. Four of the five stations are operated by the University of Illinois; Agriculture Department and State Water Survey. The other station is operated by Argonne National Laboratory. Data for these stations are not provided in this report but can be obtained through http://nadp.sws.uiuc.edu/.

The USGS National Water-Quality Assessment (NAWQA) Program  is a long-term program with goals to describe the status and trends of water-quality conditions for a large, representative part of the Nation's ground- and surface-water resources; to provide an improved understanding of the primary natural and human factors affecting these observed conditions and trends; and to provide information that supports development and evaluation of management, regulatory, and monitoring decisions by other agencies.

Assessment activities are being conducted in 42 study units (major watersheds and aquifer systems) that represent a wide range of environmental settings nationwide and that account for a large percentage of the Nation's water use. A wide array of chemical constituents is measured in ground water, surface water, streambed sediments, and fish tissues. The coordinated application of comparative hydrologic studies at a wide range of spatial and temporal scales will provide information for water-resources managers to use in making decisions and a foundation for aggregation and comparison of findings to address water-quality issues of regional and national interest.

Communication and coordination between USGS personnel and other Federal, State, and local interests are critical components of the  NAWQA Program. Each study unit has a local liaison committee consisting of representatives from key Federal, State, and local water-resources agencies, Indian Nations, and universities in the study unit. Liaison committees meet to discuss their information needs, monitoring plans and progress, desired information products, and opportunities to collaborate efforts among the agencies. Additional information about the NAWQA Program may be accessed from http://water.usgs.gov/nawqa/.

In Illinois, a pilot study of the upper Illinois River Basin began in 1986. The three major work elements of the study were (1) an analysis of available information, (2) fixed-station sampling, and (3) synoptic sampling. The fixed-station sampling program was operated in cooperation with the Illinois Environmental Protection Agency. The fixed-station sampling program, through August 1990, consisted of eight stations that were sampled on a monthly basis; after August 1990, only four stations continued to be monitored. Synoptic sampling was conducted for trace metals and organic compounds in bottom material and for dissolved oxygen, bacteria, nutrients, and trace organic compounds in water. All sampling was discontinued in April 1992. Selected data from the upper Illinois River Basin NAWQA pilot study's fixed stations were published in the 1987-92 annual reports.

The upper Illinois River Basin study was re-established in 1997 to (1) define the present surface- and ground-water quality, (2) if possible, identify trends in surface- and ground-water quality, (3) evaluate the effects of different land uses on stream and ground-water quality, and (4) identify areas where water quality is affected adversely by natural and/or human processes. Major water-quality issues being studied include sediment, dredging and associated contaminants; nutrients and eutrophication; dissolved oxygen; trace inorganic and organic compounds; effects of increasing urbanization; effects of ground-water mining on ground-water quality; degradation of aquatic habitat; and invasion of non-native species. Surface-water, ground-water and biological sampling activities began in 1999. The intensive data-collection phase of the upper Illinois River Basin study unit was completed during water year 2001. Selected data from the upper Illinois River Basin NAWQA study have been published in this report since 1998.  Sampling continues to assess water-quality trends.  Three surface-water stations were sampled on a regular basis through water year 2004 and a subset of 10 water-table wells are sampled in alternate years.  

Work on the lower Illinois River Basin NAWQA study unit began in 1994. After 2 years of planning and historical data review, data collection began in 1996. Major rivers in the basin are the Illinois, Vermilion, Mackinaw, Spoon, Sangamon, and La Moine Rivers. During water years 1997 and 1998, monthly surface-water samples were collected at fixed stations and analyzed for nutrients, major ions, suspended sediment, and selected pesticides. Guidelines for collecting and processing stream-water samples are found in Shelton (1994). A series of habitat surveys were completed and biological samples were collected. The ground-water samples were analyzed for major ions, nutrients, selected pesticides and selected trace metals. Guidelines for collecting and processing ground-water samples are found in Koterba, Wilde, and Lapham (1995). The intensive data-collection phase of the lower Illinois River Basin study unit was completed during water year 1998. Selected data from the lower Illinois River Basin NAWQA study have been published in annual reports beginning in 1997.  Sampling continues to assess water-quality trends.  Three surface-water stations were sampled on a regular basis through water year 2004 and a subset of five deep glacial aquifer wells are sampled in alternate years.  

The USGS National Streamflow Information Program (NSIP) is a long-term program with goals to provide framework streamflow data across the Nation.  Included in the program are creation of a permanent Federally funded streamflow network, research on the nature of streamflow, regional assessments of streamflow data and data bases, and upgrades in the streamflow information delivery systems.  Additional information about NSIP may be accessed from http://water.usgs.gov/nsip/.