10. NPDES Permits

NPDES is an acronym for National Pollutant Discharge Elimination System.  According the Clean Water Act, any point source discharge into a navigable waterway must have an NPDES permit from the U.S. Environmental Protection Agency (USEPA).  The program has three types of permits including surface water discharge permit (for pollutants discharged from a point source such as a pipe), pretreatment industrial user’s permit, and storm water permit.  There are 51 active permitted point source discharges (NPDES permits) into Darby Creek Watershed (see Map 22).  The Ohio EPA monitors Ohio ’s streams and determines if there are violations of NPDES permits.  (Appendix N) provides a narrative of each NPDES location in the Darby Watershed.

A total of 48 facilities are small wastewater treatment plants (WWTP) serving small cities, villages, schools, business, and mobile home parks.  These small plants which discharge between 2,000 and 100,000 gallons per day (GPD) are referred to as “package plants.” These package plants combine to account for approximately 4.5% of the wastewater flow, 9.4% of cBOD₅ (dissolved oxygen needed to break down organic materials in water), 35.3% of the ammonia loading, and 6.8% of suspended solids loading discharged into Darby Creek Watershed.  The disproportionate amounts of the above parameters is result of improper operation and maintenance of many package plants in the watershed.

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Last updated: April 7, 2009.