Sierra Club, a California Non-Profit Corporation v. Union Oil Company of California, a California Corporation, Defendants

The Sierra Club brought a citizen enforcement action against Union Oil Company of California (“Union Oil”) alleging that Union Oil violated the terms of its National Pollutant Discharge Elimination System (“NPDES”) permit on seventy-six occasions. After a five-day trial, the district court found no violations of the permit. The court excused some of the reported exceedances of permit limitations by application of an upset defense (an excuse for permit violations when circumstances occur that are beyond the reasonable control of the permittee), some on the ground that reports of exceedances were mistakes caused by sampling error, and some by application of a purported de minimus exception to the Federal Water Pollution Control Act (“the Act”). Sierra Club appeals from these rulings and from the district court’s denial of its motion for leave to file an amended complaint before trial. We reverse.

Sierra Club’s original complaint alleged that Union Oil exceeded its permit limitations on seventy-six occasions during the period between 1979 and 1983. Union Oil’s principal defense is that approximately fifty of the exceedances were due to circumstances beyond Union Oil’s reasonable…