WASHINGTON -- House Speaker Nancy Pelosi and other lawmakers criticized the Coast Guard Thursday over an audit that said accident investigators were "generally inadequate" to the task of responding to last fall's oil spill in San Francisco Bay.

"These shortcomings impacted the response," Pelosi, a San Francisco Democrat, said in a prepared statement at a House hearing on the Nov. 7 accident, calling the failure "disconcerting."

The Department of Homeland Security's inspector general concluded that the Coast Guard's Vessel Traffic Service could not have prevented the Cosco Busan freighter from sideswiping a bridge support and spilling 53,000 gallons of fuel into the ecologically sensitive bay.

But the inspector general's report faulted the agency's accident casualty investigators for not conducting timely drug and alcohol tests on the ship's crew members or Coast Guard personnel monitoring channel traffic the day of the crash.

The report said that none of the three investigators initially sent to the scene was fully qualified.

"I am deeply disturbed to learn that marine casualty investigators who responded to this incident were not qualified," said Rep. Elijah Cummings, D-Md., who heads the House Transportation subcommittee that oversees the Coast Guard.

Coast Guard Rear Adm. Brian Salerno said he was also disturbed by the finding and promised to institute new training to ensure it wouldn't happen again. "It should not have happened," Salerno said. He said the Coast Guard was also trying to bulk up the ranks of its marine casualty investigators.

The inspector general's finding that that the Coast Guard's Vessel Traffic Service wasn't at fault in the spill contradicts claims by attorneys for the pilot who was at the helm of the Cosco Busan freighter when it bumped the San Francisco-Oakland Bay Bridge in heavy fog. The pilot, Capt. John Cota, has pleaded not guilty to federal civil charges of violating environmental laws.

The inspector general also said that although the size of the spill initially was wildly underestimated -- at 140 gallons -- that did not affect attempts to stem the damage, as some local officials have charged.

Thursday's hearing comes on the heels of a two-day National Transportation Safety Board hearing that produced startling revelations about Cota, including heavy use of prescription drugs and that he had a DUI conviction in 1999.

Asked about the DUI, Salerno said the Coast Guard had known about it and Cota voluntarily surrendered his mariner's license for a time until going through an Alcoholics Anonymous program. But he acknowledged that there's no obligation for pilots to self-report such convictions except for when their license comes up for renewal, which happens only every five years.

Cummings said that should change.

NTSB hearing testimony and transcripts also revealed that Cota was confused about navigational devices on the ship the morning of the accident and mistook a bridge support for an opening in the bridge while going over electronic charts with the ship's China-based master.

Cota's attorney Jeff Bornstein has argued that the Coast Guard's traffic service could have warned Cota he was about to crash into the bridge instead of simply questioning his course.

The inspector general report seemed to discount that possibility, which lawmakers also have raised.

"There was nothing the San Francisco Vessel Traffic Service could have done to prevent" the accident, according to testimony by Anne L. Richards, assistant inspector general for audits at the Department of Homeland Security. "The VTS watchstanders followed their operating procedures."

The Coast Guard said its traffic service is primarily advisory, unlike air traffic control.

The audit said, however, it's a "major concern" there aren't more experienced marine casualty investigators in the San Francisco port.

"By not administering the drug and alcohol tests, the Coast Guard is unable to positively rule out impairment of the VTS watchstanders as a contributing factor to the incident," the audit said.