PORTLAND--Stan Geiger, a Lake Oswego ecologist wanted his audience to learn something about the "human element" of the Great Wetlands Debate.

So he told a story about a field trip in west Eugene, where he was helping local officials identify wetland areas on private property.

"A farmer came out with a shotgun and told us to get off his property," Geiger recounted. Geiger patiently explained to the farmer that he was there on a peaceful mission--to find evidence of marshy, swampy areas that are so beneficial to plants, wildlife and water quality.

The farmer gripped the shotgun tighter.

Discovery of wetlands is anathema to property owners. It can mean a huge difference in the value of their land. It can mean months or years of painful, expensive bureaucracy if the owner wants to build on or develop the land.

If a developer is ordered to make up for wetlands destroyed by a construction project, the "mitigation" can add $25,000 to $40,000 per acre to the cost of the project, said Steve Pfeiffer, a Portland land use attorney.

That is why the national real estate community is sweating swamp water over mounting pressure to preserve what remains of the damp, boggy, greasy wetland areas that dot urban areas.

Wetlands, the best of which are full of food, diverse plant species and rich soil, are lures for ducks, heron, eagles, beaver and a wide array of wildlife.

But they also represent some of the last remaining prime real estate--ideal for condominium complexes, office campuses and shopping malls.

Local government officials this year identified about 1,400 acres of wetlands in west Eugene, one of the prime industrial growth areas in the county. But under a less restrictive definition proposed by the Bush administration, about 500 fewer acres would be classified as wetlands.

Geiger and Pfeiffer were among the speakers at a two-day "Wetlands 1991" symposium that ended Friday.

Real estate developers, land use lawyers and private land use consultants hear what they will be up against as Congress and the Bush administration attempt to forge a compromise between the needs of progress and the needs of the environment.

The conflict is a formidable one.

To begin with, the federal government is having a horrendous time defining precisely what constitutes a wetland. Changes occur almost weekly, often in the form of letters, memos, news releases or White House position papers.

And even tiny modification in the definition can mean huge changes in the amount of land that must be protected.

For example, a parcel of land in Portland has many classic wetland features. But the majority of vegetation is a type of grass that doesn't appear on the government's list of wetland plant life. Therefore, it's not a wetland--at the moment.

If the grass suddenly gets added to the list--probably at the well-intentioned whim of a government scientist--much of the land must be reclassified as a wetland, and it becomes subject to all the associated protections.

"It's almost like an endangered species problem," Geiger said. "One plant added to the list can add 20 percent more" to the nation's wetland inventory.

To developers and property owners, who work with budgets and bottom lines, the unpredictability is nightmarish.

"Your land is either worth 10 cents a foot or $2.50 a foot, depending on what day of the week it is," Pfeiffer said.

Most changes are the result of court decisions, which have favored broad criteria for wetlands, and political pressure, which often is aimed at tightening the criteria to please various constituents.

The result is a confusing set of policies that cannot be relied upon. In some cases, building permits have been approved by one government agency only to be overruled by another because it used a stricter wetlands definition.

At the heart of the problem are vast differences of opinion over the real value of wetlands. When Geiger tells a property owner he has found a wetland, "I am in effect finding a defect on their property," he said.

"It's like a used car lot, where you put a sticker on a car that says it has a bad transmission," he said. Only a fool would buy it.

But there are those who believe in the environmental benefits of wetlands, who see their ability to shelter wildlife, to harbor rare plants, to filter toxins from water, to control flooding naturally.

"Often, these areas are the last breath of open space for growing urban communities," said Dan Stotter, a Eugene environmental lawyer who attended the wetlands seminar. "They provide an escape hatch."

The fight over wetlands is only going to grow more intense, Stotter said.

Because they cost more to develop swampy areas often are the only remaining real estate left to build on in growing cities, he said. As such, they are becoming more and more valuable as a development commodity.

"When you have a scarcity question, sometimes the battle gets particularly fierce," Stotter said.