Biological studies may involve surveys of an entire river system or may be oriented toward a site-specific problem evaluation. The majority of the bioassessments conducted by DNR are the problem evaluation type such as the assessment of point source discharges, the evaluation of remediation program success, or the investigation of a more general concern such as nonpoint source effects. DNR employs three types of problem evaluation bioassessments reference site evaluations, site investigations, and biosurveys that are distinguished primarily by the level of effort involved. Reference site evaluations are limited in effort and generally involve only one station.
Site investigations are more intensive, generally, including two to three stations.
Biosurveys are the most comprehensive and usually include five or more stations. Qualitative biological assessment and habitat survey protocols have been developed by DNR for wadable rivers and streams and have been used in all types of problem evaluation surveys. The DNR biological and habitat assessment protocols were developed in 1991 as the result of the increasing demand for a more vigorous and standardized evaluation of nonpoint source impacts. DNR bioassessments can consist of an evaluation of any one or combination of three parts including the macroinvertebrate community, the fish community and habitat quality. In 1993, approximately 185 stations were surveyed using biological procedures, including 106 for nonpoint source and 79 for point source evaluations.