GM DISCHARGED ZINC, COPPER, AND LEAD IN AMOUNTS THAT EXCEEDED ITS NPDES PERMIT EFFLUENT LIMITATIONS DURING THE PERIOD FROM MAY 1989 THROUGH MAY 1992. ON MARCH 1, 1993, EPA FILED, AND SUBSEQUENTLY AMENDED, AN ADMINISTRATIVE COMPLAINT AGAINST GENERAL MOTORS, ALLEGING THAT GM VIOLATED SECTION 301(A) OF THE CWA BY FAILING TO COMPLY, ON 92 OCCASIONS, WITH DISCHARGE LIMITS FOR COPPER, LEAD AND ZINC, AS SET FORTH IN A 1988 NPDES PERMIT FOR GM'S PONTIAC FIERO ASSEMBLY FACILITY IN DETROIT. THE COMPLAINT SOUGHT A $125,000 PENALTY FOR THE VIOLATIONS. GM ARGUED THAT THE METALS IN QUESTION WERE NOT POLLUTANTS UNDER THE CIRCUMSTANCES OF THE CASE, THAT IT WAS NOT POLLUTANTS UNDER THE CIRCUMSTANCES OF THE RECEIVING WATERS BECAUSE THE METALS ALLEGEDLY WERE CONTAINED IN RAINFALL AND HAD LEACHED FROM THE METAL ROOF AND GUTTERS OF GM'S BUILDING, AND THAT THE