SYNOPSIS: * DUNCAN, OK IS A TOWN OF SLIGHTLY OVER 22,000 PEOPLE LOCATED IN SOUTH CENTRAL OK ALONG THE EAST BANK OF CLARIDY CREEK IN THE SW 1/4 OF SECTION 20, TOWNSHIP 1S, RANGE 7W. THE CITY OWNS AND OPERATES A WASTEWATER TREATMENT PLANT WITH A DESIGN CAPACITY OF 3.5 MGD. THIS POTW PRESENTLY TREATS INDUSTRIAL DISCHARGES AND HAS AN EPA-APPROVED PRETREATEMENT PROGRAM. ITS HYDRAULIC AND ORGANIC LOADINGS HAVE BEEN GREATLY REDUCED IN RECENT YEARS, PRIMARILY BECAUSE OF THE LOSS OF MAJOR IN- DUSTRIES FROM THE AREA AND THE SYSTEM. CURRENT DAILY FLOWS AVERAGE 2.3 MGD. * DISCHARGES FROM THIS POTW ARE SUBJECT TO NPDES PERMIT NO. OK0026638. THIE EPA-ISSUED PERMIT BECAMUE EFFECTIVE ON AUG 30, 1986, AND WILL EXPIRE AT MIDNIGHT ON AUG 29, 1991. IT AUTHORIZES THE DISCHARGE OF TREATED WASTEWATER FROM THE POTW TO CLARIDY CREEK, TRIBUTARY TO COW CREEK, TRIBUTARY TO BEAVER CREEK, TRIBUTURARY TO THE RED RIVER, DURING THE MONTHS OF NOV THROUGH MAY. THE PERMIT PROHIBITS THE DIS- CHARGE OF EFFLUENT FROM JUNE TO OCTOBER, HOWEVER, THE SUMMER TIME MONTHS WHEN CLARIDY CREEK'S FLOW IS RELATIVELY LOW. * DISHCHARGES FROM THE POTW HAVE VIOLATED THE FINAL EFFLUENT LIMITS OF THE CITY'S NPDES PERMIT AN