Is It Safe To Swim In The Ohio River

ORSANCO is asked frequently if it is safe to swim in the Ohio River, and the answer to that question is invariably answered, “Yes and no.” Most if not every activity that humans engage in carries with it some level of health risk, and recreating in or on the Ohio River is no different.

Obvious risks include river currents, floating or submerged debris, commercial and recreational traffic, as well as water quality conditions. Risk to human health from body contact is monitored and evaluated by measurements of bacteria levels. Bacteria such as Fecal coliform and Escherichia coli (E. coli) are used as indicators of fecal contamination, and certain levels (criteria) have been established to protect human health from gastrointestinal illnesses which can occur through accidental ingestion of contaminated water during recreational activities.

ORSANCO conducts monitoring for Fecal coliform and E. coli every week from April through October at several locations in Pittsburgh, Wheeling, Huntington, Cincinnati, Louisville and Evansville.

Click here for the most current bacteria data

Sample results are generally not available for 48-72 hours due to the time required for analysis, quality assurance and data processing.


Here is guidance for using the criteria for the Ohio River for the protection of human health from contact recreation, with further explanation below:

E. coli: Monthly geometric mean not to exceed 130/100 mL, nor any sample exceed 240/100 mL.

The E. coli criteria, which were developed by the United States Environmental Protection Agency, were established to prevent no more than 36 illnesses per 1000 people.

A geometric mean similar in concept to an average, but is calculated as:

Geometric Mean = ((X1)(X2)(X3)……..(XN))1/N
Where: X = Individual value, N = Sample size (Number of values)

Bacteria conditions in the Ohio River can change rapidly, particularly as a result of rain which flushes bacteria into the Ohio River from such sources as overland runoff and combined sewers. Bacteria levels can rise rapidly as a result of rain, and in the larger urban areas, generally drop back to normal levels within 48-72 hours. Bacteria conditions in the Ohio River during extended dry periods are generally below the criteria, (with the exception of certain known areas), while bacteria conditions after rain may likely exceed the criteria, (with the exception of certain known areas), while bacteria conditions after rain may likely exceed the criteria.

Quick guide to using bacteria data and criteria:

If the most recent sample for E. coli is less than 240, and it has not rained since, Ohio River water quality conditions are probably more favorable for swimming.

If it has rained in the last 48-72 hours, or bacteria levels in the most recent sample were above the criteria, Ohio River water quality is probably less favorable for swimming.

Bacteria levels are generally lower upstream of urban areas than downstream of urban areas; however it should be recognized that everywhere on the Ohio River is downstream of some bacteria sources.

ORSANCO recognizes that bacteria data can be confusing and difficult to interpret, so please do not hesitate to contact ORSANCO should you have any questions.