Length - The Ohio River runs 981 miles from the confluence of the Allegheny and Monongahela rivers in Pittsburgh, Pennsylvania, to Cairo, Illinois, where it joins the Mississippi. It flows through or forms partial borders of six states: Pennsylvania, Ohio, West Virginia, Kentucky, Indiana and Illinois.
Watershed - The land area where all flowing water eventually reaches, the Ohio River watershed covers 205,000 square miles across 15 states. States within the watershed include: Pennsylvania, Ohio, Kentucky, West Virginia, Indiana, Illinois, Tennessee, New York, Virginia, Maryland, Georgia, Mississippi, Alabama, North Carolina and South Carolina.
Tributaries - The largest rivers flowing into the Ohio include Tennessee River, Cumberland River, Wabash River, Allegheny River, Monongahela River, Kanawha River and Allegheny River.
Drinking water - The river supplies about five million people with drinking water. That is complicated by the heavy industrial and commercial use of the river and their potential for hazardous spills that can contaminate drinking water supplies.
Pollution - The Ohio is commonly cited as the most polluted river in the United States. According to reporting from the Louisville Courier-Journal, this is based on analysis of the U.S. Environmental Protection Agency’s Toxic Release Inventory [TRI], which tracks industrial discharges. According to 2013 TRI data, 23 million pounds of toxic chemicals were released into the Ohio River, outpacing the Mississippi and New rivers for pollution. The Ohio River Valley Water Sanitation Commission [ORSANCO], which compiled the report on TRI data, warns that the numbers don’t account for river volume or chemical concentrations.
ORSANCO - an interstate commission established to control water pollution in the basin. Commissioners are appointed by the federal government and the governors of eight member states—Illinois, Indiana, Kentucky, New York, Ohio, Pennsylvania, Virginia and West Virginia.
ORSANCO has for decades set standards for pollutants discharged into the river. Environmental advocates credit basin-wide standards for improving water quality along the length of the river. The commission controversially voted in 2019 to make those standards voluntary for states. Those in favor of the revision say water quality is still protected by the U.S. Environmental Protection Agency [EPA] and state regulations, and states now have more flexibility in meeting those standards. Opponents, including some ORSANCO commissioners, say more than 100 ORSANCO standards are not covered by several member states.