Crimes Against Earth Second Largest Oil Spill Ever The Ixtoc I exploratory well suffered a blowout on June 3, 1979, in Mexico’s Bay of Campeche, 600 miles south of Texas. The well was not brought under control until the next year, by which time 140 million gallons had spilled into the bay. The only larger spill occurred during the 1991 Gulf War, when Iraq dumped—deliberately—up to 462 million gallons of oil into the Persian Gulf.