MARK BOYAR IS A DIFFERENT sort of NIMBY. Though he lives in the Seward Park neighborhood, he’s battling to keep development out of a forested river valley in the Cascade foothills, an hour from his home.

Boyar has spent the better part of the last 10 years fighting to preserve the Middle Fork of the Snoqualmie River—the most pristine in King County—which stretches out northeast of North Bend. He and other environmentalists have been struggling to put in place a long-term recreation and conservation plan for the surrounding valley, which has long been known for shootings, car dumpings, and a generally lawless atmosphere.

But now Boyar feels those years of work are threatened by one very wealthy homebuilder.

Steve Gillis, one of the nation’s most successful biotechnology executives (he cofounded Immunex), and his wife Anne have bought a piece of property deep inside the Middle Fork area. According to documents filed with the county, the couple plans to construct a four-bedroom home topped by a “tower,” along with tennis courts, a 5,000-square-foot “activity center,” four parking stalls, and heated passageways between the estate’s three buildings.

“This is the first major setback to the vision of a publicly owned valley,” Boyar laments, standing just outside the Gillis property, a peaceful little clearing in the shadow of beautiful jagged peaks. “It’s just heartbreaking, given the amount of community effort that’s gone into saving this place.” King County has already spent over a million taxpayer dollars buying up private lands along the river, while Paul Allen’s foundation and various other land trusts have acquired nearby parcels as well.

The Gillis structure will be the first luxury home erected this far into the Middle Fork forest, bringing with it more lights, impervious surfaces, and other habitat disruption. Most worrisome to Boyar, the Gillises will not rely on a generator, but instead plan to lay wires across several miles and run their electricity in from North Bend. “Most people don’t have the means to do that,” Boyar observes. The introduction of electricity will, in turn, drive up the value of the surrounding land parcels, making them more attractive for development and thus harder for preservationists to acquire.

THE CASE HAS BECOME a rallying point for environmentalists and county officials, who are now seeking to stop a potential outbreak of millionaire mansions in the remaining forests of King County.

King County Executive Ron Sims has put forward a controversial new zoning plan that would restrict new housing development in the county’s so-called Forest Production District (or FPD), which includes the Middle Fork. Sims’ plan would have the effect of locking up huge swaths of timberland—much of it prime for development—and preventing it from being turned into new homes. Hearings on his proposal are scheduled to begin at the County Council next week.

The Forest Production District encompasses nearly two-thirds of the county’s land, reaching from Carnation and Black Diamond east to the Cascades and the National Forests. A good portion of that land is owned by big timber companies such as Weyerhaeuser and Plum Creek.

Before selling off their land to other foresters or real estate developers, the timber companies typically break their large tracts down into lots, which may be further subdivided for houses. Since the mid-’90s, county zoning has allowed FPD land to be broken into lots no smaller than 80 acres. The idea was to keep the land in chunks that are large enough to support continued forestry and too large to convert to some other use.

In actual practice, county officials admit, many smaller lots were created, due to local decision-making that was not always in accord with countywide policy. And hundreds of smaller lots were created before this zoning was put in place.

Now county officials are finding that the 80-acre limit itself is insufficient. “The timber companies tell us that they’re actually seeing, in some places, a market for 80-acre [residential] lots,” says Lori Grant of Sims’ Office of Regional Policy and Planning. (Eighty acres is four times the size of Gas Works Park.) With all the new high-tech wealth around here, “it’s no longer prohibitive for someone to buy up an 80-acre parcel and just bring all their own services in,” says Nancy Keith, executive director of the conservation group Mountains to Sound Greenway.

To stem the potential tide of development, Executive Sims wants to prohibit new residential construction in the Forest Production District, except for lots that were created before January 1. “We’re trying to prevent this from becoming ‘estate zoning,'” says Grant.

Sims had originally proposed a much tougher measure, forbidding new homes on any lot bigger than 10 acres, no matter when it was created or purchased. Such a rule change would have stopped the Gillises, who bought their 20-acre property last year.

But in public hearings Sims and his staff caught hell from rural landowners and had to back down. Now they propose to allow houses on any lot that was carved out before this year. “People who have already purchased property out there to build their dream home can still do so” under the revised rule, says Grant. Close to a thousand lots will be grandfathered in.

EVEN WITH ALL the loopholes, Sims’ ideas have not been warmly received in the Republican-controlled King County Council—indeed, they may be dead on arrival.

“There are no Republicans willing to vote for any more downzones,” says Republican King County Council member Chris Vance. “It’s simply wrong for the government to say, ‘Here’s what you can or can’t do on your property,’ and then five years later say, ‘Oh, we changed our minds.'”

Other property rights activists are up in arms as well. “A person’s right to build a cabin on his own property is one of the most—if not the most—fundamental attributes of real property ownership,” declares Bill Kombol, manager of Palmer Coking Coal, a 67-year-old mining company in Black Diamond that still manages some 200 acres of forest land. “Some people seem to think that rights reside with the king, and he grants you privileges,” says Kombol. “But our country was founded on different principles.”

Chris Brownell, a landowner in the Lake Joy area who is actively opposing Sims’ plan, says, “It’s unrealistic to expect no building. If that’s the goal, they should offer to buy everyone out.”

The interest group that would be most directly affected by Sims’ plan—the timber industry—has been relatively quiet so far. Frank Mendizabal, a spokesman for Weyerhaeuser, will say only: “We have an interest in these types of changes and we’re going to continue to monitor what happens.” Of course, the zoning rules aren’t permanent, as the industry well knows, and can be undone again with the next change in county leadership.

BOYAR SAYS THE GILLIS home is “the poster child for what’s going to happen if Sims’ plan isn’t accepted by the county.” Still, is one little house—or even one giant mansion—in the middle of 80 acres such a big deal? Policy analyst Lori Grant says that the problem is the domino effect: “If you have people who are quite wealthy moving deep into the [forest], it will drag more development with them.” In the Gillis case, for example, she says, “Other properties out there that didn’t have hope of getting electricity—and so couldn’t be developed—now might be.”

Eventually, she says, those remote residents start demanding “a full level of services” from government, such as emergency response, fire, police, school buses, and paved roads. They also start to complain about the noise and other unpleasantness that comes from living in close proximity to mining and timber cutting—which, Grant says, “is still a very important industry for King County.”

For his part, Steve Gillis offered this comment when reached at the office of his latest hot biotech company, Corixa: “We are trying to build a single-family house, which is a permitted use of the property we purchased. And we’ve hired some well-trained consultants to help us stay within all regulations.”

Indeed, the Gillises are clearly making some effort to go lightly on their surroundings. According to county files, their housing plan calls for removing only three trees from the site and leaving everything else intact. Only six of their 20 acres will be built on.

And the site doesn’t exactly reside in virgin forest. It’s reached along a gravel and dirt road littered with a couple abandoned shacks and cars, as well as the remnants of a major meth lab that was busted a few years ago. A handsome, now-doomed two-bedroom cabin from the previous owner already sits on the Gilleses’ property.

This part of the Middle Fork has been logged out several times and today is mostly lined with skinny alders, the first tree species to move in after a clearcut. “Forests take time,” says Boyar, as he conducts his tour.

Boyar holds out little hope that he will be able to stop the Gillis project, though he says he’s going to “push for every study possible.” The nonprofit Land Conservancy of Seattle and King County has been trying to interest the biotech executive in another site, so far without success.