Degradation and Recovery of Scioto River (Ohio, USA) Fish Assemblages from Presettlement to Present-Day Conditions
Chris O. Yoder, Edward T. Rankin, Vicki L. Gordon, Lon E. Hersha, and Charles E. Boucher
Abstract.—A 37-year series of standardized fish assessments in the Scioto River (Ohio, USA) since 1979 coupled with historical information documents a near complete recovery from heavily polluted conditions in the late 19th and early to mid-20th centuries. Nearly 100 fish species were extirpated downstream from the city of Columbus (Ohio, USA) by sewage and industrial pollution. The 1972 amendments to the Federal Water Pollution Control Act (Clean Water Act) mandated the control of sewage and industrial pollution. Reductions in loadings of untreated or poorly treated sewage were incremental. Full recovery to near-prepollution composition and abundance took more than two decades after advanced wastewater treatment was achieved. Unpolluted tributaries served as recolonization sources for populations of extirpated species. These positive changes extended across all fish assemblage members as evidenced by increased values of the Ohio index of biotic integrity; modified index of well-being; native species richness, density, and biomass; and the reduced incidence of external anomalies on fish. These restoration successes and their documentation were facilitated by the Clean Water Act that set forth the goals for water quality standards and treatment technology for reducing water pollution and conducting baseline and follow-up monitoring. An important lesson learned was that serious doubts that existed in the 1970s about the feasibility of advanced wastewater treatment technology and the attainability of water quality standards in an effluent dominated river were completely erased by the demonstrated improvements in the fish and macroinvertebrate assemblages in the Scioto River. The extent of improvements in recreational opportunities have tracked that of the biota by an increased use for fishing, canoeing, kayaking, and related forms of recreation. However, maintaining these improvements will require continuation of high levels of wastewater treatment and water quality standards. A growing human population that is forecast to increase by one-half million persons by 2050 makes maintaining the currently high levels of biological integrity a continuing challenge. Given the lessons learned with the mosaic of stressors in the Scioto River over the past 150 years, we believe this challenge can be met successfully.