The Wards of Potomac still enjoy the deer that peek through their picture windows. But they are so sure that their sylvan setting will change radically because of the proposed construction of 1,600 homes nearby that they are reduced to hoping that a sewage treatment plant be built there instead. At least, they say, it will keep the density down.

The Wards live near Avenel Farm, a 1,018-acre tract, just 10 miles from the White House, that has beenfarmed for generations. It is a mile from the Beltway, on Persimmon Tree Road opposite Congressional Country Club. Now the farm is a prime prospect for development at triple the currently zoned two-acre density that would have allowed some 500 homes. The Wards say they could live with that, but not with the latest proposal.

"It's unconscionable," said Fred Ward, a professional photographer who lives with his wife, Charlotte, and four children at the end of a country lane. "Normally," said Ward, "you would expect the county to be your partner in thwarting their [developers'] greed. In this case, the county appears to be their partner."

In Montgomery County, the battle lines are drawn. As the planners see it, the issue is saving farmland from the onslaught of development by channeling growth to closer-in areas, even where farmland may still exist.

The procedure is known as "transferable development rights" or "TDRs." The idea is to severely restrict building in the rural upper county without devaluing the property. In return for taking away their chances to cash in on development, the county awards TDRs to affected upcounty landowners, which they may sell to developers. To assure a market for TDRs, the county has targeted downcounty areas for denser development than would otherwise be allowed by existing zoning without TDRs.

A total of 88,000 acres of upcounty land have been designated "sending areas," in planner's jargon. Downcounty communities have been designated "receiving areas" for as many as 17,600 houses more than normal zoning would allow.

In language fit for the nuclear age, planners speak of maintaining "a critical mass" of farmland. Others worry about their towns and neighborhoods being "ground zero" for added development. But despite all the atomic talk, the issue is as old as the ages--the land and how to use it.

In the last decade, TDRs have saved only 184 acres of farmland from future development across the United States. Other counties close to Washington rejected the whole idea as unworkable.

But Montgomery County planners, operating in a jurisdiction with a reputation for progressive proclivities, plunged ahead with the concept on an unprecedented scale, toward the twin goals of directing cost-effective growth near existing public facilities, and retaining enough farmland to help supply the metropolitan market with fruit, vegetables and dairy products. (Wheat, the county's major crop, goes elsewhere.) As a by-product, the planners promised an increase in the number of affordable units downcounty, an outcome as yet unrealized and often questioned.

"It won't work where planning and zoning aren't as advanced" as in Montgomery County, asserts Norman Christeller, chairman of the county planning board. Of course, he adds, "There are going to be people raising questions narrowly focused on their neighborhood, but we and the County Council are looking at it from a broader perspective."

When first proposed for Montgomery in 1980, the TDR concept was so obscure that nobody came to the first hearing. Now, the phrase can fill a hall. As the plan has advanced, "ground zero" has moved from Olney to the Route 29 corridor to Potomac, whose residents are resisting this incursion into their gentrified lifestyle. Intangible abstractions such as "the greater public good" have come into direct conflict with the hard realities of "my land . . . my home."

When word got around last winter, 200 residents turned out at Wootton High School to protest the planners' proposal to designate 37 receiving areas in Potomac, Travilah and Darnestown. The plan would permit 6,175 TDRs, nearly 1,500 more units than otherwise allowed, with 1,240 to go in Potomac and most of those on Avenel Farm. The planning board approved the draft plan with little change. Now the battle has shifted to the County Council, which held its own hearing last Thursday.

In the Fairland section of eastern Montgomery County, seven miles from Silver Spring, the battle has ended, but not the anger. Residents raged over the county's plans to double to 3,500 the number of units allowed on vacant land along the Rte. 29 corridor.

"This area right now is lovely the way it is and they're doing their damndest to wreck it," said Gloria Marconi, a free-lance illustrator who lives with her teen-age son in an 18th century farmhouse they're restoring on a wooded acre near Rte. 29.

Dissent lingers even in Olney--the county's pilot project in the TDR concept where both sending and receiving areas were incorporated in what planners call a "closed circuit." "They took prime farmland being farmed and made it a receiving area," observed Frank L. Blunda, who lives in an Olney subdivision. "The citizens gained nothing."

But the planners are buoyed by the Olney experience, where a developer with land in both sending and receiving areas will erect 456 units on 228 acres, double the density allowed under zoning. Meanwhile, he will keep his 760-acre horse farm intact.

Montgomery planners have been "preserving" the countryside, on paper at least, for more than two decades, ever since the famed "Year 2000 Plan" of 1961 and the follow-up "Wedges and Corridors" document of 1964. The idea was to encourage development along the well-traveled highways and keep greenery in between in "wedges" that included Potomac, among other areas.

Mostly, the plans worked. Interstate 270 in particular became an extension of the Capital Beltway. Research and development firms and subdivisions sprouted along its path, while much of the remaining upcounty stayed rural. But individual homes also began to sprout amidst the wheat and cornfields. To limit such scattered development, the county raised the minimum lot size in 1974 from a half-acre to five acres.

Royce Hanson, the then planning board chairman, asserted that the new five-acre zone would be "permanent . . . and one we do not anticipate needing change for some very substantial period of time."

Four years later, although harvested cropland had increased and subdivision activity slowed in the county, Hanson and his staff of bright, young planners saw a potential threat to upcounty farmland and open space. They feared the spread of five-acre "farmettes" with kids on mini-bikes and conflict over common farming occurrences such as stray cows or tractors on the roads.

Explains planner Perry Berman: "Residential development and farming are like oil and water. Our plan was to zone the whole critical mass for farming." So five-acre zones became 25-acre zones with one TDR for each five acres as a way of compensating the landowner, "in the interests of equity," according to County Council Chairman Neal Potter.

But not all landowners would be equally compensated, because, with varying soils and slopes, not all land is equally ripe for development. "You can live in White's Ferry out where they'll never build homes and it's not suitable to farm or build," grouses George Lechlider, a Laytonsville farmer who heads the Montgomery County Farm Bureau, "and they get the same number of TDRs I do."

Some contend the 25-acre downzoning itself amounts to governmental overkill. "From a development standpoint, we did not need it," said Charles Jamison, a Poolesville realtor. "The soils dictate development. The very best farmland we have" in his end of the county is unsuitable for development.

Nonetheless, the County Council adopted the program by a 6-to-1 vote in September 1980, with only Rose Crenca of Silver Spring in dissent. "It's a great exercise in land use for a college professor to assign to students," said Crenca, who remains a skeptic.

Her reservations are shared by Robert Brennan, a retired army colonel and a former builder, who is a dissenter on the county planning board. Housing built on TDR receiving land will cost more, not less, he asserts, especially on the two tracts in Potomac and many more in eastern Montgomery that had been zoned for the same density. Now, builders must buy TDRs to develop the equivalent amount. "The economics are not resolved in my mind," Brennan said.

Stephen Kaufman, an attorney with the land use law firm of Linowes & Blocher, said, "take one-third of the land out of housing, it makes the rest more expensive. Even with TDRs, it may allow you to get some town houses, but they're gonna be pretty expensive."

The problem, as he sees it, is more basic. "Montgomery County has so many priorities, they're running into each other, almost hopelessly," Kaufman said, listing agricultural preservation, affordable housing, a high quality environment and adequate transportation and public facilities as among the goals to which all county politicians and planners subscribe.

Kaufman represents the developers of Avenel and other TDR tracts. Another lawyer in his firm represents upcounty landowners who have filed a lawsuit over what they regard as devaluation of their property because there is no guaranteed market for their TDRs. The lawsuit is widely regarded as a prod to get the county to designate receiving areas and to fulfill its promise to create a "Development Rights Bank" to buy TDRs until a substantial private market exists.

In the meantime, the county is rife with rumors of contracts between farmers and developers for TDRs, contingent on places to put them. Anthony Natelli, a Potomac resident who heads the firm seeking to develop Avenel, said he owns 40--from another property his company has upcounty--far fewer than he needs. A Chevy Chase firm recently disclosed it had acquired 87 TDRs from a Poolesville area turf farm, at a price of $4,750 each, to build more town houses elsewhere in the county.

For now, the value of any given TDR is largely ethereal. Mostly, upcounty landowners appear to be waiting for an active market to develop as more receiving areas are approved.

So the planners and politicians proceed. Today, Potomac. Tomorrow, Damascus, Gaithersburg, Clarksburg, Wheaton-Glenmont, Four Corners. Wherever close-in green space remains, the decision-makers are determined to see that TDRs follow. And the beauty of it all, they say, is that the taxpayers won't pay a cent to save upcounty's wide open spaces. But another generation of politicians and planners could change their minds about the future of the upcounty. Zoning is not immutable, under law.

On the patios of Potomac they are raising funds for a future lawsuit of their own and circulating petitions for a referendum to ban the use of TDRs in the name of saving farms. "If the opportunity arises, please emphasize that we are not against agricultural preservation upcounty," name gatherers have been advised. "We are against trying to reach that goal by disrupting long-standing zoning and environmental protection for downcounty areas."

The whole concept still remains elusive to many. "Most people don't even know what it's about," said Isabel (Doe) Fitts, a petitioning Potomac activist. "They think TDR is Teddy Roosevelt."