Biological Integrity of Surface Water

The Federal Clean Water Act of 1972 had as its stated goal “to restore the physical, chemical, and biological integrity of the nation’s waters.” The legislation set in motion various programs that have resulted in much cleaner water in the United States. Part of the effort included funds to monitor chemistry, biology, and habitat of lakes and streams to see if we’re making any progress. For example, every wastewater treatment facility in the country does some kind of chemical monitoring to assure that a chemical standard is being met as the water is released back into the natural environment. Habitats such as swamps, lake shores, and stream banks are being protected or restored. And now water resource professionals are using biological monitoring tools to measure ecological health. Plants and animals that live in water are continuously exposed to the many chemicals and other “pollutants” that may occur there. Many of these pollutants are virtually undetectable by chemical analysis and have no water quality standards established to regulate them. When combined with habitat alterations, they may drastically alter aquatic communities. This makes the process of biological monitoring a very good way to identify and solve many water quality issues that cannot be addressed by chemical sampling alone.

Biological monitoring is done most often by comparing the numbers and types of plants and animals present in a stream or lake with those that would be expected to occur at a similar “reference” site (one in which human influence is minimal). The aquatic communities most commonly used to make these measurements are fish and benthic macroinvertebrates (small animals without backbones such as insects, snails, and crustaceans that live on the rocks and sediment of lakes and streams). When scientifically tested methods of collection and analysis are used, a numerical score of ecological health (sometimes called an index of biological integrity) is obtained that is both accurate and reproducible. Where low index scores occur, trained professionals can often use the biological information to also diagnose the cause of the problem (low dissolved oxygen, toxic substances, excess nutrient or sediment inputs, etc.). Biological monitoring is also very helpful in doing “before and after” studies that can determine if an environmental restoration effort has been successful.

Water Resource Professionals in Indiana Focusing on Biological Monitoring of Water Quality

  • Carol Newhouse (Hoosier Riverwatch)
  • Stacey Sobat (Indiana Dept. of Environmental Management)
  • Jeff Frey (U.S. Geological Survey)
  • Greg Bright (Commonwealth Biomonitoring)
  • Mark Pyron (Ball State University)

Related Resources

Baker, N.T., and Frey, J.W., 1997, Fish community and habitat data at selected sites in the White River Basin, Indiana 1993-95. U.S. Geological Survey Open File Report 96-653, 44 p., accessed April 4, 2014 at:

Bright, G., Belmonte, E., and White, G., 2014, Macroinvertebrate communities before and after best management practices, Indiana Dept. of Natural Resources, Lake and River Enhancement Program, Indianapolis, IN, accessed April 4, 2014 at:

Davis, W.S., and Simon, T.P. [ed.], 1995, Biological assessment and criteria: tools for water resource management and decision making, Lewis Publishers, Boca Raton, FL. 432 p.

Indiana Department of Environmental Management (IDEM), 2013, Hoosier Riverwatch volunteer stream monitoring training manual, accessed April 4, 2014 at:

IDEM Office of Water Quality, 2005, Summary of protocols for probability based site assessment for watershed program field activities, accessed April 4, 2014 at:

This page written and maintained by Greg Bright of Commonwealth Biomonitoring.