A Canyon Apart : Environment: Plans to develop the pristine, 171-acre area in Diamond Bar is an exciting dream for builders and for city and school officials. To critics, it is an ecological nightmare.

Jan Dabney’s dream for Sandstone Canyon is Don Schad’s nightmare.

Wedged between the droning traffic of the Orange Freeway and tracts of neat suburban houses, Sandstone Canyon may seem a relatively unremarkable chunk of ravine and ridges.

But to Schad, it is Diamond Bar’s Grand Canyon.

“There is no other place in the world just like this canyon,” said Schad, a 70-year-old self-taught naturalist whose house overlooks one of Sandstone’s steep, wooded cliffs. “My nightmare is that it all will be destroyed.”

To Dabney, the spokesman for two major developers, and to city and school officials, the 171-acre canyon represents a rare opportunity to create a dream: a $170-million, meticulously planned development.

They hope to build a junior high school, a 28-acre park with nature trails winding through oak and walnut woodlands, ball fields, a 290,000-square-foot commercial area, and 200 single-family homes selling in the $500,000 range.

It is estimated that the commercial development alone would create anywhere from 464 to 1,160 new jobs in the city.

The potential economic benefits to Diamond Bar, population 55,000, are vast and in the long run, 48-year-old Dabney said, worth what would be a virtual remaking of the landscape.

“I think the legal term is ‘overriding considerations,’ ” he said of the trade-offs as he walked along the Sandstone hillsides and created a verbal picture of what one day might be there.

If approved by the Planning Commission and City Council, the proposal calls for the removal of close to 800 coast live oak trees, most of the oaks in Sandstone. The development would also mean filling the half-mile-long canyon with an 80-foot-deep layer of dirt, to be scraped from the surrounding ridges.

James DeStefano, the city’s community development director who has been overseeing creation of the South Pointe Master Plan, acknowledges that the project “clearly involves a reconfiguration of the canyon.”

“Significant amounts of vegetation will be removed and replaced,” he said. “We recognize that to some folks this is an oasis in suburbia. But we recognize we have a responsibility to look at the broader needs of the community and . . . believe the benefits outweigh the detriments.”

In the works for two years, the proposal has raised the ire of environmentalists and prompted questions from state and federal environmental officials.

Both the U.S. Fish and Wildlife Service and the state Department of Fish and Game have written letters expressing concerns about the draft of the project’s environmental study.

An official of the U.S Fish and Wildlife Service wrote that “the project site represents habitats that are rapidly disappearing in Southern California.”

A state Fish and Game official raised the issue that the study had not adequately addressed the potential impact on the California gnatcatcher--a tiny, rare songbird being considered for addition to the federal endangered species list--and another sensitive species, the San Diego coast horned lizard.

Furthermore, the regional official, Fred Worthley, questioned the environmental report’s conclusion that the loss of the oak and walnut trees would not represent a significant impact on regional biological resources.

Cal Poly Pomona biological sciences professor Jack Bath, who has done studies on mountain lions for the last three years in the region, cites another concern: the potential impact on a small population of cougars that move regularly through the canyon on their way to places as far away as Anaheim Hills and Whittier Narrows.

“It’s an atrocity,” said Bath. “A single project like this could block the (cougar) pathway” and in effect, he said, cause the demise of the few mountain lions remaining in Diamond Bar.

As Schad scanned some of the 5,000 slides he has taken in Sandstone, he spoke of his heart-wrenching love affair with the canyon.

“In this canyon we have every (plant and animal) that’s in Diamond Bar, except one kind of wildflower. It’s been home to wildlife for thousands of years. The canyon itself is between 800,000 and 1.2 million years old.”