A combined sewer overflow (CSO) occurs when storm water and sewage, carried in a single pipe, overload the sewer system and flow untreated into rivers and streams. CSOs can carry a variety of pollutants, including raw sewage, debris, chemicals and bacteria.
Mon Valley Sewage Authority’s CSO Flag Alert Program is designed to warn the general public of possible river contamination from CSOs. While these programs do not prohibit or discourage river recreational activities, they do caution recreational users to limit contact with river water when boating, fishing, water skiing or engaging in other river recreational activities.
Advisory Programs operate annually from May 1 until September 30 to coincide with Mon Valley Sewage Authority’s NPDES permit summer reporting period. If overflows occur, Mon Valley Sewage Authority will raise an orange CSO flag at the Wastewater Treatment Plant (located across the river from the Herman Mihalich Boat Launch) and will notify the public accordingly via the website.
This website will be updated when the system returns to dry weather operation, 72 hours later. At this point, the CSO flag is also lowered to indicate dry weather operation.
The Combined Sewer Overflow alerts are active from May 1 through October 31 annually.
