Earthmovers belch as they taper a future neighborhood from sage-and-scrub hilltops overlooking rolling canyons. Like other developments reaching as far as the eye can see, the machines are devouring the flaxen hills that are home to scores of endangered species such as the California gnatcatcher and the fairy shrimp.
But many conservationists aren't condemning this latest housing project outside San Diego. Rather they are touting the agreement that led to it as a turning point in the United States conservation movement.
The idea behind the agreement: In exchange for the rights to build houses here, developers give up rights to develop hundreds of thousands of acres elsewhere - from Los Angeles to Mexico. While these land swaps are not new, the current San Diego plan is the largest of its kind - setting aside 172,000 acres to protect 85 imperiled plants and animals - and is seen as a practical middle ground between the interests of developers and environmentalists.
It is being used both as a model for revisions to the 20-year-old Endangered Species Act, now being drafted in Congress, and for hundreds of other agreements in states and cities nationwide. If the idea passes a public-comment period that began Sunday, as is likely, it could change the future of plant and animal preservation in North America.
This is "the most comprehensive and imaginative conservation plan in history," says US Interior Secretary Bruce Babbitt, who has been working on the idea since 1993 to avoid what he says would have been "the next, big environmental train wreck" - a fight over the tiny, endangered bird known as the California gnatcatcher.
Quietly in the works for half a decade, the land swap is being increasingly questioned by opponents right and left, who see it either as an assault on property rights or a sellout to builders. Mainstream environmental groups are also divided.
"The idea is controversial even in the environmental community, which is split over whether it is good or bad," says Joel Reynolds, analyst for the Natural Resources Defense Council (NRDC).
This Thursday, the organization is releasing a major study that includes recommendations concerning clearer standards, public participation in planning, assurances made to landowners, and independent review.
"We feel the concept is good but it has very serious flaws which need to be corrected," adds Reynolds.
That concept started with a decision to harness a little-known California law called the Natural Communities Conservation Program that empowered counties and cities to plan open space for endangered species. Some of the largest landowners in southern California joined with local government officials five years ago. Starting with a single contribution of 21,000 acres by Orange County's Irvine Company, which led to dozens of others from small landowners, Orange County was able to approve a plan conserving 38,000 acres.
Last month, San Diego approved its much larger 172,000-acre plan.
"This plan demonstrates that the preservation of ecosystems and the unique plants and wildlife they support is compatible with growth and development," says San Diego Mayor Susan Golding, who campaigned four years ago on ending enmity between developers and environmentalists.
But a key provision is coming under increasing scrutiny. Known alternately as "no surprises" and "mutual assurances," the provision holds that participating landholders have no further responsibility for protecting endangered species on the lands they have donated into reserves.
If fire, or other natural calamity occurs, for instance, causing listed species to decline - or if a lack of sufficient contiguous acreage causes their numbers to diminish through biological isolation - participants are not required to act.
Such future immunity is, in fact, a primary attraction for landholders to participate. But it ignores the unpredictability of nature, environmentalists say, and goes against the overall intent of saving endangered species.
"These plans are inflexible and ignore the realities of how species might respond to surprises," says Eric Glitzenstein, lawyer for Spirit of the Sage, a coalition of environmental groups that is fighting the agreements. "It's a classic case of leaping before anyone takes a serious look."
Because of a major federal court decision in March, a chance for more serious looks began just this week. The judge ruled that the San Diego and other similar agreements throughout California were going forward illegally without public comment periods, and established the formal, 60-day period.
How the "no surprises" provision will fare under such scrutiny has direct consequences on how federal policy might evolve in the future. A clause with similar wording to the San Diego conservation plan is currently written into draft legislation to revise the Endangered Species Act.
"We are adapting whatever is successful in individual examples of this idea into the national bill," says Mark Snider, communications director for Sen. Dirk Kempthorne (R) of Idaho, co-author of the bill.
Challenging the plan
Although the San Diego plan has been approved by the city, it still must pass muster by county and other local governments who are expected to vote on the issue before autumn. Key conservatives such as Bill Horn, chairman of the San Diego Board of Supervisors, are challenging the plan for other flaws.
"Fifty-eight percent of this county is already run by the government, and I don't think they need to control any more," says Mr. Horn, who still opposes the plan, despite the fact that the city has approved it. "This is not about saving species; it's about land control."
Despite such comments, a growing number of observers seem to feel the San Diego model, while perhaps flawed, might still be America's best chance to overcome the developer versus environmentalist battle.
"These agreements have shown that governments, landowners, and environmentalists can resolve a lot more by collaborating on these issues than if we all stay in our bunkers and heave grenades at each other," says Don Barry, acting secretary for fish, wildlife, and parks at the US Department of Interior.