Environmental Protection Agency Administrator Stephen Johnson told The Chicago Tribune the June permit Indiana regulators awarded to BP complied with the U.S. Clean Water Act.

"As an agency we need to honor that permit," he said.

The permit lets the British energy company release 1,584 pounds of ammonia from its Whiting, Ind., refinery into the lake every day -- 54 percent more than its previous limit.

It also lets BP dump 4,925 pounds of "suspended solids," or tiny sludge particles that escape water-treatment filters -- 35 percent more than before.

Indiana also let the oil giant continue dumping 2 pounds of toxic mercury into the lake every year until 2012, when it will need to meet a stringent 1995 federal standard for mercury pollution that would reduce the discharge to 8/100ths of a pound, the Tribune said.

The U.S. House of Representatives voted 387-26 last week to urge Indiana to reconsider the permit.

A coalition of lawmakers also implored Johnson to put the permit on hold while BP considers additional upgrades as it expands the refinery.