Something that's created a division in Maryland as wide as the Chesapeake Bay these days is a bundle of bills designed to protect the waterway from further pollution.

Outnumbered Eastern Shore lawmakers are desperately seeking Western Shore allies to help kill proposed land use restrictions around much of the bay. Environmentalists, having pushed for the restrictions for several years, are just as desperate to avoid a last-minute defeat.

Tomorrow or Tuesday, the Senate is likely to approve the regulations, and hearings are scheduled to begin this week on a host of bills introduced by Eastern Shore lawmakers that, in effect, would change some of the key regulations once they are passed.

Not in a dozen years has an issue so clearly divided the state's Eastern Shore lawmakers from their colleagues on the other side of the bay.

Eastern Shore representatives, aided by developers and real estate agents, have busied themselves visiting their Western Shore counterparts, trying to convince them that the regulations are too harsh and that the alternative bills are vital for the Eastern Shore's survival. Environmentalists, saying these bills are meant to undermine the regulations, are trying to drum up a telephone call and letter campaign in support of the regulations.

In essence, the restrictions, known as the Critical Areas regulations, are designed to focus future development on areas that are already densely developed. They would strictly control development in areas that are currently moderately developed and severely restrict development in undeveloped "resource conservation areas."

It is the final category that has provoked the most strenuous opposition, because it limits building to one house on every 20 acres. Eastern Shore representatives say this is going too far, and they have introduced a bill that would allow one house on every eight acres instead.

The purpose, said Del. Daniel Long (D-Eastern Shore), is not to weaken the Critical Areas regulations but "to fine-tune them to minimize the effect on individual landowners, while at the same time improving upon the quality of the water. And we think we've done that. It's very difficult for someone who's not familiar with the area of the Eastern Shore to appreciate how much open space there is -- and how much development we need."

This was the argument made Friday morning, when a contingent of lawmakers and planners from the Eastern Shore called on the Prince George's County delegation. They said people on the Western Shore had little idea of the severe effect the Critical Areas legislation would have on those living on the other side of the Chesapeake Bay.

"The difference between our proposal and their proposal is like being in a war," said William Livingston, a planner from the Eastern Shore town of Salisbury. "It's the difference between killing people from 20,000 feet up in a bomber, or bayoneting them to death in a foxhole. When you see a real sample of what is happening, it makes a difference. It's not philosophy."

Most of the Prince George's delegation seemed uninterested, but Livingston did find some support. "It seems to me that one dwelling in 20 acres is a minifarm," said county Democratic Del. Richard Palumbo.

Edgar Hilley, a lobbyist for the Maryland Board of Realtors, said he believes it will be "politically impossible" for most legislators to oppose the Critical Areas legislation.

"There's no question, politically, that it would be very dangerous to vote against it," he said. "Everybody wants the Chesapeake cleaned up."

So Hilley, too, is arguing in support of the Eastern Shore bills as he visits legislators from the Western Shore. Limiting construction to one house on 20 acres is "not necessary to preserve anything," he argued. "It diminishes the land value. There's no question that the value of existing homes would go up. But land would devalue. Who can afford 20 acres?"

Some observers say that Eastern Shore legislators may have made a political mistake in believing their constituents are solidly opposed to the Critical Areas regulations. "If you were to poll over there," said John R. Griffen, Maryland's assistant secretary of natural resources, "I think you would find a simple majority generally favoring this type of program . . . . They want to keep the Eastern Shore from being heavily developed."

Long, however, sees it differently. "You have got to remember that Somerset County, just as Montgomery and Prince George's and Anne Arundel, has to fund the school system and pave roads. It has to provide police protection. it has to run government. In order to do that, it has to have some ability to grow, to improve its tax base."

Scott Burns, a lobbyist for the Chesapeake Bay Foundation who has been urging the defeat of the Eastern Shore bills, has been showing legislators results of a foundation study suggesting the regulations would allow the Eastern Shore to build far more new houses than it needs. According to that study, current demand indicates 6,481 new houses would be built in the Critical Areas on the Eastern Shore by 2000, while 45,966 houses would be allowed under the regulations.

"We're going to be fighting really hard," Burns said, particularly focusing on the bill that would allow one house on eight acres.

"That bill seems to be the one that's a real problem," he said. "Most of the other bills are totally unnecessary or are more blatant attempts to confuse the issue. I don't give them much of a chance."

While Burns has been working on the legislators in Annapolis, John Kabler, director of Maryland Clean Water Action, said he has 18 canvassers working throughout the state every night, looking for supporters of the Critical Areas regulations and urging them to telephone or write their lawmakers. "We want to kill these 'anti' bills," he said. "Just knock them out."