Conducting Biological Assessments of a Large River: The Ohio River (Mississippi River Basin)

ORSANCO is an interstate water pollution control agency that operates programs for water quality monitoring and assessment, which includes biological sampling since 1957.  Initially, the biological aspect consisted of collecting fish community information from lockchamber rotenone sampling, which has provided an extremely useful dataset for assessing long-term trends in fish community condition. In 1991 ORSANCO began exploring nighttime boat electrofishing (EF) as a supplemental technique to lockchamber surveys.  This method became the primary technique for routine monitoring and assessments.  In 2003, EF data were used to create an Ohio River Fish Index (ORFIn) which was useful in the assessment of the Ohio River’s Aquatic Life Use for 305(b) reporting.  The ORFIn was later modified (mORFIn) incorporating continuous rather than discrete scoring methods and directly incorporating instream habitat into final index scores.  In addition, benthic trawling has also been explored as a potential sampling technique on the Ohio River.  Future monitoring and assessment protocols will consist of EF surveys annually at 15 randomly drawn 500 meter sites in each of three navigational pools.  In addition to fish collections at each site, macroinvertebrates, water and sediment chemistry, and habitat data will be collected to holistically assess the condition of the Ohio River.