MBI announces the release of a major report on the historical ecological success story of Central Ohio’s two major rivers.  This report, entitled Biological and Water Quality Assessment the Middle Scioto River, Lower Olentangy River, and Selected Olentangy Tributaries 2020: Including a 50 Year Retrospective Analysis of Available Biological and Water Quality Data. Franklin and Pickaway Counties, Ohio (MBI Technical Report MBI 2022-4-6), is a major milestone in the management and assessment of rivers and streams as affected by 50 years of the implementation by the Clean Water Act (CWA) by private, local, state, and federal agencies and organizations. The scope of the report’s 2020 biological and water quality assessment, included the Scioto River mainstem between Griggs Dam in Columbus to Canal Park in Circleville, the Olentangy River mainstem from Powell Rd. to the mouth in downtown Columbus, and three Olentangy River tributaries in Columbus, two of which are part of Project Blueprint

The City of Columbus Division of Sewers and Drains (DOSD) sponsored the July-October 2020 biological and water quality assessment of the Olentangy and Scioto Rivers. The assessment included:

  • 25 sites on the Scioto River mainstem between Griggs Dam in Columbus to Canal Park just below Circleville and a single site on Big Walnut Creek;
  • 11 sites on the Olentangy River mainstem in southern Delaware and Franklin Counties; and,
  • 10 sites located across three (3) Olentangy River tributary subwatersheds, two that are directly related to Project Blueprint (Adena Brook, Beechwold Run) and the other related to MS4 stormwater permitting and local watershed group interests (Rush Run).

Consistent with prior surveys of this area dating back to 1979, the sampling included water chemistry, sediment chemistry, habitat, and biological assemblages. Chemical analyses were conducted for 24 laboratory analytes and four field parameters in water and seven (7) heavy metals and multiple organic chemical compounds in sediments. E. coli bacteria counts were determined to assess the status of the Primary Contact Recreational (PCR) use. Parameters consistent with the proposed Ohio EPA nutrient effects assessment methodology were also collected including two forms of chlorophyll a and continuous dissolved oxygen (D.O.), temperature, pH, and conductivity in the Scioto and Olentangy River mainstems. Habitat quality was assessed with the Qualitative Habitat Evaluation Index (QHEI) and the biological assemblages included fish and macroinvertebrates consistent with Ohio EPA methods and the biological criteria for assessing the status of aquatic life use designations per the Ohio Water Quality Standards (WQS) (OAC 3745-1-07) at all sites. The sampling was performed under an approved Level 3 study plan per the Ohio Credible Data Law (ORC 6111.5) and Regulations (OAC 3745-4).

Historical analysis of data spanning more than 50 years focused on the Scioto River in and downstream from Columbus and as affected by major municipal wastewater treatment plants, the sanitary and storm sewer systems, the hydrological dynamics, and habitat changes mostly related to dam removals through that time period. The analysis documents trends in commonly measured pollutants in water and sediment, habitat, and the fish and macroinvertebrate assemblages with the highlight being the attainment of the Exceptional Warmwater Habitat (EWH) aquatic life use designation downstream from Big Walnut Creek to Circleville. The lower Olentangy River retrospective included the period from 1987-2020. The overall results show that, for the most part, both the Scioto and Olentangy Rivers meet their CWA goals after 50 years of pollution controls and WQS development. The long term dataset and the attending analyses are unprecedented as an evaluation of the success of water quality based permitting and setting WQS dating back to the post-1972 CWA mandated controls of pollution for major point sources in general and municipal wastewater treatment in particular and specifically for the City of Columbus Jackson Pike and Southerly facilities. Updating the long term database in 2020 also allows any added benefits of CSO elimination by the OARS tunnel project completed in 2015 to be better documented. The recovery of the rich aquatic biological fauna from grossly polluted conditions of the late 19th and early to mid-20th century and through 2020 make this one of the best CWA success stories in the U.S.

 One of the most important lessons learned from examining 50+ years of monitoring results in the Scioto River mainstem is that the CWA mandated reductions in loadings of sewage pollutants from the Columbus sewer system via water quality based permitting resulted in water quality improvement sufficient to allow for what is essentially a full biological recovery. This recovery happened despite the serious doubts about the treatability of sewage and attainability of the biological goals of the CWA that prevailed at the time they were first introduced in 1972. From the first reported evidence of serious water pollution in the Scioto River as far back as the 1880s to the installation and operation of advanced wastewater treatment via Project 88, it took more than a century before sufficient actions to reduce pollution enough to fully meet CWA goals actually took place. Part of the delay was due to the costs of wastewater treatment and the almost constant pursuit of the engineering technology that was required to reduce pollutants to the levels necessary to meet the 1972 CWA goals. These achievements did not come easily nor without a significant expenditure of public funds at the federal, state, and local levels. The consequences of the original doubts about the efficacy of advanced wastewater treatment and the attainability of CWA mandated WQS in an effluent dominated river were exemplified when the Scioto River was proposed as a limited aquatic habitat in the 1978 WQS (i.e., Limited Warmwater Habitat). This designation represented a lower water quality goal than that envisioned by the 1972 CWA and it was disapproved by U.S. EPA in 1978, which illustrated the critically important role of federal agency oversight of state and local actions at that critical time. Once it was demonstrated to be achievable and effective by sustained biological monitoring, advanced treatment has become the accepted minimumtechnology for municipal wastewater discharges in Ohio and much of the U.S. 

Perhaps the most unheralded part of the demonstrated success of water quality based permitting are the contributions made by the tens of individuals that were directly involved in achieving improved wastewater treatment by the City of Columbus. This includes people in the city, state, and federal agencies and private sectors that were involved in debating and making the policy decisions, setting the WQS, developing the permits, designing the treatment facilities, and financing the capital improvements. However its success also depended on the water utility rate payers and advocates for improved water quality, all of whom can take a share of the credit for the resulting improvements that all can enjoy today. The sum total of these accomplishments are the legacy left to today’s counterparts to protect and uphold. The extent of improvements in recreational opportunities have tracked that of the fish and macroinvertebrate assemblages as evidenced by an increased use of the river for fishing, canoeing, kayaking, and related forms of recreation including multiple new public access points, trails, recreation areas, and new organizations dedicated to improving access to these benefits within the greater metropolitan area.

The report is organized by the two distinct river mainstem reaches and tributary subwatersheds for the 2020 study area – the Scioto River mainstem, the Olentangy River mainstem, and the Olentangy Tributaries. With the exception of portions of the Summary and Conclusions, Introduction, Methods, and Study Area, each Results and Discussion section of the report is written as a stand-alone reporting of the results, thus certain descriptions of pollutants and indicators are redundant between the three major sections. 

Please direct any questions to Chris Yoder, MBI Research Director at cyoder@mwbinst.com.


Chris Yoder