The Ohio River, flowing nearly 1,000 miles through or along six states, has a rich history. Native Americans called it “Oyo” (“The Great River”), and European explorers named it “La Belle Rivière” (“The Beautiful River”). It served as a major route for trade, westward expansion, and formed part of the border between free and slave states. Due to its extensive use and industrial past, concerns about its water quality are common.
Current Water Quality
The Ohio River’s water quality has significantly improved over the last six decades, a major change from the 1950s when it was used for untreated waste disposal. Despite this progress, parts of the river still do not fully support all designated uses, including aquatic life, public water supply, and recreation. State agencies report that nearly 70% of assessed streams in the Ohio River Basin do not meet water quality standards.
Monitoring shows reductions in pollutants like ammonia, phosphorus, and lead in the water, and decreasing concentrations of PCBs, mercury, and arsenic in fish. However, nutrient over-enrichment and historical contamination persist. While improvements are evident, some reports still rank the Ohio River among the most polluted in the U.S. due to the volume of toxic discharges.
Primary Pollutants and Their Sources
Pollutants in the Ohio River come from industrial operations, agriculture, and municipal systems. Historically, industries like steel mills and petroleum discharged toxins directly. More recently, facilities such as coal-fired power plants, aluminum manufacturers, and petrochemical plants released substantial toxic pollution; nearly 41 million pounds were discharged into the Ohio River Basin in 2020. Industrial discharges include nitrates (92% of toxic emissions in 2013) and mercury (a 500% increase between 2007 and 2013). Petrochemical expansion may increase chemicals like vinyl chloride, trichloroethylene, and benzene.
Agricultural runoff, especially in the lower basin, carries excess herbicides, pesticides, and nutrients (nitrogen, phosphorus) from farm fields. These nutrients cause eutrophication and harmful algal blooms. Municipal wastewater, primarily from combined sewer overflows (CSOs), also impacts the river. During heavy rain, CSOs release untreated wastewater and bacteria like E. coli.
Legacy pollutants like PCBs, dioxins, and mercury persist in the sediment. Emerging contaminants, including PFAS, personal-care products, microplastics, and pharmaceuticals, are also present. Acid mine drainage from abandoned coal mines introduces high concentrations of metals and sulfur, making water acidic and contributing to upper basin pollution.
Impacts on Ecosystems and Health
Pollution in the Ohio River impacts both aquatic ecosystems and human health. The ecosystem shows declining species abundance and disrupted food chains, with only 50 of 80 original mussel species remaining. Though some sensitive species have returned, aquatic community health is still affected. Habitat degradation from channelization, dredging, and damming further stresses the ecosystem. Excess nutrients from agricultural runoff cause harmful algal blooms, creating “dead zones” by depleting oxygen and producing toxins like microcystin, harming aquatic life.
For human health, the Ohio River is a drinking water source for five million people, making contaminants a concern. Untreated water can contain bacteria, viruses, heavy metals, pesticides, and industrial chemicals, potentially causing gastrointestinal illnesses or increasing cancer risk. Exposure to PCBs and dioxins can lead to liver and kidney cancers, while nitrates link to developmental and birth defects. Mercury, a neurotoxin, can impair fetal brain development.
Fish from the river accumulate toxins like mercury, PCBs, and PFAS, posing risks to consumers, especially pregnant women, nursing mothers, and young children. Recreational contact, particularly after heavy rains, risks gastrointestinal illnesses from elevated bacteria or algal bloom toxins.
Conservation and Cleanup Efforts
Extensive efforts are underway to monitor, protect, and improve the Ohio River’s water quality, largely driven by regulatory frameworks like the Clean Water Act of 1972, which mandates state water quality standards. The Ohio River Valley Water Sanitation Commission (ORSANCO), established in 1948, manages interstate pollution. ORSANCO monitors water quality, sets discharge standards, and assesses fish populations, bacteria, and harmful algal blooms. Government agencies, including the EPA and state environmental protection agencies, regulate industrial discharges and collaborate on pollution mitigation. Non-profit organizations like the Ohio River Foundation, National Wildlife Federation, and Environmental Law & Policy Center also advocate for cleaner water and participate in restoration.
Initiatives include investments in wastewater treatment infrastructure, promoting agricultural soil conservation, and watershed restoration projects like Ohio’s H2Ohio Rivers Initiative, which focuses on dam removal, litter cleanup, and acid mine drainage remediation. Public awareness campaigns, such as marking storm drains with “No Dumping, Drains to River,” also aim to prevent pollution.
Public Safety Recommendations
For recreational activities on the Ohio River, understanding safety recommendations is important. While water quality has improved, swimming carries risks like strong currents, floating debris, and commercial boat traffic. It is advisable to avoid swimming after heavy rainfall due to increased bacteria from urban runoff and combined sewer overflows. ORSANCO provides weekly water quality reports to help the public make informed decisions about recreational contact.
Fish consumption from the Ohio River also has advisories due to contaminants like mercury, PCBs, and PFAS in fish tissue. State health departments issue guidelines, often recommending limited consumption of certain species or fish from particular areas. Sensitive populations, including pregnant or nursing women and young children, face stricter consumption limits. To minimize exposure, choose smaller, leaner fish, and remove skin and fatty areas before cooking, ideally by baking, broiling, or grilling to allow fats to drip away.