BLACKWATER NATIONAL WILDLIFE REFUGE, MD. -- The Blackwater is a laid-back sort of river, a languid, inky stream that winds through a maze of marshland on its way to Dorchester County's Fishing Bay.

From headwaters to mouth, the river is but 28 miles long. In some places, it's barely deep enough to float the flat-bottomed boat that refuge biologist Bill Giese steers expertly between its muddy banks.

But for all its lack of flash and dash, the tranquil Blackwater is running in rarefied company these days. The National Park Service has recently identified it as a leading candidate for the nation's first "river park." It is an ambitious -- and potentially controversial -- plan to protect an entire river "from end to end, undeveloped and undammed, existing totally as it is for all time."

The Park Service already protects pieces of rivers, either within national parks or as part of the Wild and Scenic Rivers System. The river park, in the words of Park Service Director William Penn Mott Jr., would preserve an entire river system "in its natural condition so that everyone would be able to see what rivers looked like before man came here."

The Blackwater is one of only three rivers in the country under consideration for the project. And while the proposal is still little more than a gleam in Mott's eye, the Blackwater's candidacy already has raised eyebrows in Dorchester County, including those affixed to the well-known brow of the county's leading politician, Democratic state Sen. Frederick C. Malkus Jr.

"We're going to keep an open mind," said Malkus, whose family owns extensive farmland along the Little Blackwater, a tributary that is included in the Park Service's protection plan. "But I don't know what . . . they would do that we're not doing. We're not developing it."

The Blackwater made the Park Service's candidate list in part because much of its length is already protected by a 15,600-acre federal wildlife refuge designation and most of the rest, including tributaries, is relatively undeveloped.

But to Malkus and Republican state Del. Richard Colburn, who also lives along the Little Blackwater, the proposal looks like the old one-two punch: Under state law designed to clean up the Chesapeake Bay, much of the river's watershed is already off-limits to intensive development. The federal government would add a layer of regulation.

Also, local landowners are opposed to development, and therefore they see the proposed federal intervention as overkill. As Malkus interpreted it, the federal interest means one thing: "They're going to take away some more of our rights," he growled.

The state regulations are, to say the least, unpopular in Dorchester County, where distrust of government is as much a way of life as crab boils on summer weekends. So while the Park Service has not detailed its proposal to local residents, the guard is already up along the Little Blackwater.

Park Service officials say that they are looking for cooperative agreements and that, despite its working name, the "river park" would not necessarily be a national park -- which could mean forbidding hunting in one of the Eastern Shore's most popular waterfowl areas.

"They say existing laws and policies would continue. They're saying everything we want to hear," said Colburn. "But for how long? It would have to change eventually. What would this be if not an extension of that refuge?

"When the federal government gets involved, you'd better be wary," he said. "They control a good portion of the county now with the refuge. We don't know what it would lead to eventually."

The idea of a river park was high on Mott's priority list when he took office in 1985, in part because Interior Department studies suggested that the number of suitable sites was shrinking rapidly.

Less than 2 percent of the country's 3.2 million miles of rivers is sufficiently undeveloped to qualify as "wild or scenic," meaning that there is no development within a quarter-mile of either bank. Mott, however, wants to go considerably beyond the protections afforded a scenic stretch of river. The objective of the river park is to preserve an entire undeveloped watershed -- not just the river but also the area that drains into it.

"Finding an undeveloped or restorable river system -- well, we thought it would be impossible," said William Spitzer, a Park Service river specialist who guided the search. "Surprisingly enough, there are some."

But not many. State and federal researchers came up with 160 watersheds in the United States that were essentially free of housing developments, strip mines, forest clear-cutting and the like. Given current trends, they figure that most of those will be gone by the turn of the century.

Spitzer's team added a few other criteria, including wildlife resources, "ecological integrity" and size (at least 15 miles long), and it narrowed the list to three. The others are the Amicalola River in northern Georgia, graced with the state's highest waterfall and a scenic canyon, and Ernest Hemingway's beloved Two-Hearted River, a renowned trout fishery in Michigan's Upper Peninsula.

The rivers represent different ecological systems, and Park Service officials suggested that they may pursue protection for all three. "This isn't a beauty contest," said Spitzer. "They aren't competitive with each other."

The aptly named Blackwater is a "blackwater" river, a term applied to swampy coastal rivers whose waters are colored by decaying vegetation. The classification gives it a special cachet at the Park Service, because the national park system contains no blackwater rivers.

"It's a real good example of marsh ecology and small enough to deal with," Spitzer said. The area is home to a sizable colony of bald eagles and the endangered Delmarva Peninsula fox squirrel.

"It's being used as it was 100 years ago: traditional water activity and farming," said Spitzer.

But traditions are changing in Dorchester County, and so is the ecology of the Blackwater. The signs are visible even in the refuge, which has been under federal protection since the 1930s.

The problem is that the water level is gradually rising, flooding marshlands, waterlogging farmlands and turning much of the Blackwater into a shallow, spreading pool.

"Agricultural lands are reverting to woodland, woodland to marsh, marsh to open water," said Giese. "The change is very rapid."

Near the center of the refuge, where the Blackwater blends smoothly into a chain of ebony ponds, Giese points out a failed experiment in recreating a marsh by dredging up mud and reseeding the resultant "island." The muddy island has mostly collapsed.

Although rising sea levels may play a major part in the changes, some contend that Dorchester County is not entirely blameless. Agricultural runoff pours sediment into the river, for example, and few farmers have wholeheartedly embraced the idea of leaving a "buffer strip" between their fields and the Blackwater.

The rising waters, however, have played a part in protecting Dorchester County from certain kinds of development. "Mosquitoes keep a lot of people out," said Giese, and the difficulty of installing septic systems has been an effective deterrent to the vacation home crowd.

But the biggest deterrent to development, in Malkus' view, has been Dorchester County landowners themselves -- and he is not at all convinced that they need any help from the National Park Service.

"They want to save it, and that's what we've been doing for years. We're not selling our property to developers," he said. "If you sell in a farming area, you can't even cut your wheat if it's wash day."

Park Service officials say they are aware of the landowners' concerns and willing to talk about them. "We're at the very, very initial point," said park planner Lisa Dewey. "Our first step is to talk to all the interested parties."

The first meeting is scheduled for early next month, and it appears that the landowners will be ready.

It is not that they do not agree with the Park Service's opinion of the Blackwater. "You can get back in there and it's like man has never been there," said Colburn. "But we're a conservative people on the Eastern Shore. We fear the government telling us what to do."