The Coast Guard, which is responsible for cleaning up oil spills, was sloppy in handling 38 percent of the oil spills it responded to during the past 12 months, a new General Accounting Office study has concluded.

In the report, which will be published May 12, the GAO found that in more than one-third of the cases reviewed, the Coast Guards responded slowly, failed to take immediate cleanup action and failed to investigate minor mishaps.

Sen. Charles McC. Mathias Jr. (R-Md.) disclosed the GAO conclusions yesterday in Annapolis.

"The subject is of special, urgent concern to the people and state of Maryland because we are the custodians of America's largest richest estuary - the Chesapeake Bay," Mathias said at a Senate appropriations sub-committee hearing in Annapolis.

The GAO found that more than 7 million gallons of oil were spilled in U.S. waters last year. In Maryland alone, there were 250 reported spills, totaling more than 82,000 gallons.

Testimony at the hearing pin-pointed even worse spills in previous years in Maryland. About 500,000 gallons of oil spilled into Chesapeake Bay alone in 1976, largely as the result of a single incident at Smith Point, according to a study by the Chesapeake Bay Foundation.

They year before, a 135,000-gallon spill in Baltimore harbor occurred after a tankerman in charge of oil-loading operations fell asleep, a foundation spokesman noted. "It's like Murphy's law with a venegance in the oil transportation business," said Tom Lewis, the foundation's staff attorney. "Everything can go wrong and everything does go wrong in one way or another."

The GAO report said the Coast Guard should improve its oil spill contingency planning, reduce staff shortages established a marine safety job classification and strengthen cleanup training programs. It also cited a shortage of Coast Guard equipment for containing and dissipating oil spills.

"They're trying to do too much with too little," said Mathias, who is seeking more money for the Coast Guard cleanup programs.

Capt. Frederick P. Schubert, deputy chief of the Coast Guard's office of marine environment and systems, testified that because of understaffing, his agency can perform only about half its oil cleanup responsibilities.

An additional 150 jobs authorized by Congress last year for the oil monitoring programs were never funded by the Office of Management andBudget, he said.