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In 1991, the U.S. Geological Survey (USGS) began to implement Cycle 1 of the National Water-Quality Assessment (NAWQA) program. The long-term goals of the NAWQA program are to describe the status and trends in the quality of a large, representative part of the Nation's surface- and ground-water resources and to provide a sound, scientific understanding of the primary natural and anthropogenic factors affecting the quality of these resources. To achieve these goals, the USGS is employing a multidisciplinary approach that includes the collection of physical, chemical, biological, and ancillary anthropogenic data. These data will provide multiple lines of evidence to assess water quality. Study-unit investigations comprise the principal building blocks of the national assessment and originally consisted of 59 study areas. The study-unit boundaries are based on one or more of the following: surface-water drainage basins, the extent of ground-water aquifers, and political boundaries.
 The Western Lake Michigan Drainages (WMIC) study unit is defined by the extent of watersheds in Wisconsin and Upper Michigan that drain to the Western side of Lake Michigan. A brief description of the environmental setting and hydrologic conditions of the WMIC Study Unit as well as a summary of results from Cycle I studies can be found at http://water.usgs.gov/pubs/circ/circ1156.
In 2001, the NAWQA Program began its second cycle of intensive water-quality assessments in the Western Lake Michigan Drainages. The major difference between Cycles 1 and 2 is an increased emphasis on topical studies, which focus on developing an understanding of specific issues of concern. These issues include:
- Effects of nutrient enrichment on Streams,
- Sources, transport, and fate of agricultural Chemicals,
- Transport of contaminants to water supply wells,
- Effects of urbanization on stream ecosystems and,
- Bioaccumulation of mercury in aquatic organisms.
In addition to continued studies of status and trends in surface water and ground water, the WMIC study unit has been involved with the topical issues, conducting studies of urbanization and bioaccumulation of mercury during Cycle 2.
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