Ross D. Franklin, Associated Press
Land maintained by the Nature Conservancy spreads into the San Pedro River valley near San Manuel, Ariz. State planners are eyeing an I-10 bypass in the area to reduce traffic congestion around Tucson.

REDINGTON, Ariz. — The sign on the dusty road running past Andy Smallhouse's cattle ranch reads "No Pavement 50 Miles," and he would rather it stay that way, especially since the alternative could be a freeway.

The biggest road in the area now is I-10, about 40 miles away. But state planners are drawing lines on a map, and some of them would route a proposed I-10 bypass right through his southern Arizona spread.

"We don't see any way possible for an interstate to come through the middle of us and not interrupt what we're doing," said Smallhouse, whose great-great-grandfather established the ranch in 1884. "We might possibly profit from it, but we're not really interested in that aspect."

At one end, a bypass would allow cross-country truckers and long-distance motorists on I-10 to skirt Tucson, a metro area of 1 million. Farther north and west, a bypass could route traffic on I-10 around bigger and even more congested Phoenix.

The proposals are an outgrowth of efforts to adjust to Arizona's furious growth. Arizona and Phoenix consistently rank among the nation's fastest-growing areas, and traffic congestion has been a byproduct.

The roughly 100-mile trip from Tucson to Phoenix at times takes as long as three hours because of bottlenecks that slow motorists to a crawl at both ends.

Efforts to create an alternative have set the stage for conflicts, and not just around Smallhouse's ranch.

Similar growth-versus-environment concerns are likely to surface north of Phoenix with a separate state study of a possible alternate to a 145-mile stretch of I-17, frequently jammed with Phoenix-area residents escaping the desert heat by heading to northern Arizona's cooler high country and with commuters heading to sprawling new developments.

Some of the possible I-10 bypass routes would cross miles of desert of no particular distinction. Others, however, would put concrete near national monuments and wilderness areas.

Those include the lower San Pedro River valley, where the washboard road runs past Smallhouse's place. The north-flowing San Pedro is lined by cottonwoods and in places flows next to steep bluffs and vertical cliffs. Its above-ground flow is intermittent, but it remains one of Arizona's few undammed rivers.

Residents delight in regularly seeing javelinas, mountain lions and other wildlife in the area.

"We have a beaver dam, and it's so unique in that you look around and you have desert," said Maria Araiza Troutner, who lives about a dozen miles south of Redington in Cascabel and is active in an anti-bypass group.

State transportation officials acknowledge the possible I-10 bypass routes raise environmental concerns and other objections. But they say no decisions have been made.

"We have done due diligence in identifying the environmentally sensitive lands and the sensitive land use areas and have sought to not traverse them," said Dale Buskirk, the Arizona Department of Transportation's planning director.

Private and governmental organizations have spent $25 million to buy or protect approximately 40,000 acres in the San Pedro River valley, and it and the neighboring Aravaipa Valley present important opportunities for preserving open space, wildlife corridors and habitat for endangered native species, said Tom Collazo, the Nature Conservancy's Arizona associate state director for conservation.

The Department of Transportation has held public hearings on its preliminary study, and the Transportation Board could decide as early as Dec. 21 whether to order more detailed work.

Buskirk said that rough cost estimates on a 25-mile bypass for I-10 are $6 billion to $8 billion and that so far there's no funding.

Andy Smallhouse and his wife, Stefanie, wonder whether the products of generations of work will still be around for the next generation.

"Basically this heritage would come to an end, and that would be just at the time when my daughter and my son would be deciding whether they wanted to take over the ranch. And so to me personally, it's hard to talk about," Stefanie Smallhouse said, dabbing an eye. "As far as the future, it's (not) just a chapter in the heritage of the ranch. It could be the end."