When the governors of Maryland and Virginia were asked at a hearing last month to comment on a new federal proposal to overhaul the Chesapeake Bay cleanup accord, both were caught off guard.

It was the first that Govs. Harry Hughes and Gerald L. Baliles had heard of Environmental Protection Agency Administrator Lee M. Thomas' plan, modeled after a Great Lakes cleanup agreement, to drastically reduce the amount of pollutants dumped into the ailing Chesapeake by factories, military bases and sewer plants.

Since the June 24 hearing on Capitol Hill, the governors and Thomas have exchanged several politely worded letters, signaling a slight crack in the picture of harmonious cooperation between Democratic governors and the Republican administration in their highly touted effort to save the Chesapeake Bay.

Privately, aides to Hughes and Baliles said that the governors were miffed at Thomas' public unveiling of the plan and the implication that their own states' expensive cleanup efforts -- part of the three-year Chesapeake accord -- are not working.

"They Hughes and Baliles felt blind-sided. Thomas had not meant for that to happen," EPA spokeman Dave Cohen said yesterday. "The reason those letters were sent out was . . . Thomas immediately sensed some bristling. He was trying to assure them there was no upstaging intended and he wants to get on with doing what's best for the bay."

Earlier this month, Baliles wrote Thomas that " . . . Thomas immediately sensed some bristling. He was trying to assure them there was no upstaging intended . . . . " -- EPA spokesman Dave Cohen he would not support Thomas' new plans for cleaning up the bay. "You can't read the letter as any lack of commitment to moving forward on the bay cleanup," John Daniel, Virginia's secretary of natural resources, said in an interview. "We certainly didn't know about the proposal before they put it out on the table and I think it would've helped if we had."

Aides to Hughes said they are fashioning a response to a letter Thomas sent the week after the hearing "to clear up any possible confusion" caused by his reference to the eight-year-old Great Lakes accord.

That agreement sets out specific limits on dozens of toxic chemicals and heavy metals that dischargers are permitted to dump into the Great Lakes, based on water quality. Hughes' aides said the governor, whose term expires this year, is receptive to similar limits, based on water quality, for bay dischargers.

Thomas' proposal came after a Washington Post story last month on the decline of the nation's largest bay. The story showed that part of the reason for the decline is the large amount of pollution that dischargers are allowed to dump into the Chesapeake under permits issued by Maryland and Virginia.

The permits set dumping limits based on what technology is available and affordable to industries and sewer plants, rather than on what would improve water quality, the standard used by states adjacent to the Great Lakes.

Daniel, Virginia's natural resources secretary, said the executive council that oversees the Chesapeake cleanup has asked EPA for a briefing on the Great Lakes effort.