A comparison of methods for meeting monitoring objectives using macroinvertebrate data in the Chicago Area Waterway System

Bioassessment approaches designed to measure aquatic community health in nonwadeable systems are becoming increasingly available. The most well known, nonwadeable bioassessment programs of US EPA, USGS, Ohio EPA and Michigan DEQ include a range of techniques for collecting and assessing macroinvertebrates, as indicators of habitat and water quality stressors. The Chicago Area Waterway System is an entirely nonwadeable system constructed and heavily modified for the purpose of conveying treated effluent and providing commercial navigation. The purposeful construction generally eliminated the shallow shorelines and diverse habitats. The system limitations have resulted in the application of two macroinvertebrate monitoring methods considered appropriate for the system – artificial substrate and grab samplers. Monitoring is conducted by the Metropolitan Water Reclamation District of Greater Chicago (District). However, it is uncertain how the two methods compare in their measure of macroinvertebrate abundance, richness or composition within the limited habitat and treated water conditions. This study presents a comparison and assessment of these two nonwadeable methods, using 2001-2007, District-collected data from the Chicago Area Waterway System.