LOWELL OPERATES A PLANT THAT TREATS SEWAGE FROM LOWELL AND FROM THE TOWN OF CEDAR LAKE. THE PLANT WAS CONSTRUCTED WITH FEDERAL FUNDS AND IS DESIGNED TO TREAT AN AVERAGE OF TWO MILLION GALLONS OF WASTE WATER PER DAY. THE NPDES PERMIT HELD BY LOWELL AUTHORIZES THE DISCHARGE OF EFFLUENT FROM THE PLANT INTO CEDAR CREEK. THE PERMIT PROHIBITS ANY DIVERSION OR BYPASS EXCEPT WHERE UNAVOIDABLE TO PREVENT LOSS OF LIFE, SEVERE PROPERTY DAMAGE, EXTENDED DURATION PROCESS UPSET OR WHERE EXCESSIVE STORM RUNOFF WOULD DAMAGE THE FACILITY. ALTHOUGH LOWELL INITIALLY MET ITS PERMIT'S EFFLUENT LIMITS, MONTHLY OPERATING REPORTS FROM 1980 TO THE PRESENT SHOW RECURRING VIOLATIONS OF LIMITS FOR FLOW, BIOCHEMICAL OXYGEN DEMAND (BOD), AND TOTAL SUSPENDED SOLIDS (TSS). THE OPERATING REPORTS DEMONSTRATE THAT THE PLANT IS HYDRAULICAL- LY OVERLOADED. THE HYDRAULIC OVERLOAD IS CAUSED IN LARGE PART BY SEVERE INFILTRATION AND INFLOW OF STORM WATER INTO THE TOWN OF CEDAR LAKE COLLECTION SYSTEM. IN ADDITION TO DISCHARGES OF IMPROPERLY TREATED SEWAGE FROM THE PLANT, LOWELL IS RESPONSIBLE FOR DISCHARGES OF UN- TREATED SEWAGE FROM AN UNPERMITTED OUTFALL. LOWELL IN- STALLED AND DURING 1981 AND 1982 OPERATED A VALVE IN AN IN- TERCEPTOR LINE SERVING THE TOWN OF CEDAR LAKE. LOWELL OPER- ATED THE VALVE IN ORDER TO DECREASE THE MAXIMUM FLOW OF SEW- AGE INTO ITS PLANT. THE RESTRICTION OF FLOW DURING STORM CONDITIONS RESULTED IN DISCHARGES OF U