The regional chief of the Forest Service recently banned a practice that allowed local fire managers to let some blazes burn if they don't pose a threat.

Critics said the ruling could expose more firefighters to deadly risks like the helicopter crash that killed a pilot and eight firefighters in Trinity County on Tuesday.

That crash occurred in the Trinity Alps Wilderness, part of which has been identified as an appropriate place for the "let it burn" policy.

Called "wildland fire use," the practice has been embraced to reduce firefighting costs by allowing some naturally caused fires to run their course if they don't threaten people or structures. A small crew of firefighters is assigned to monitor the fire, but there is no massive suppression effort.

Such fires also improve forest health by thinning small trees and dense underbrush, which have accumulated after a century of aggressive firefighting on federal lands.

On July 9, in a memo to forest supervisors throughout California, Regional Forester Randy Moore banned wildland fire use for the remainder of the fire season.

In the decision, he cited a national preparedness rating system that indicates fire crews are stretched thin because of the large number of blazes burning throughout the West.

John Heil, spokesman for the regional Forest Service office in Vallejo, said the health impacts to nearby communities from smoke from wildfires are another concern that led to the decision. Extinguishing fires may have less health impact than letting them burn.

Local forest managers can no longer decide to let a forest fire burn itself out.

"At any point, (Moore) may make a modification. But at this point … the regional forester is basically overriding all those decisions," said Heil.

Timothy Ingalsbee, executive director of Firefighters United for Safety, Ethics and Ecology, said the ruling means that every fire will be fought aggressively, essentially reviving an age-old practice proven to be troublesome.

"Each and every time you send people out to aggressively fight a fire, you put their health and safety at risk," said Ingalsbee, whose group represents professional firefighters. "There is collateral damage involved in every fire fight."

He also said it represents an "irrational" paradox, because Moore cites personnel shortages as a leading reason for the ban on "let it burn" fires. Yet the ban eliminates a practice designed in part to prevent personnel shortages.

"It's causing extreme morale problems amongst the fire teams in California," he added. "They're sitting on their hands unable to do their jobs, or they're going out on suppression assignments doing what they know to be the wrong thing."

Every federal forest is empowered to adopt "let it burn" rules. Half of the 18 forests in California have done so.

The practice is a relatively new one for the Forest Service but has proven effective.

Studies have shown that letting a fire run its course costs $50 an acre, compared with $500 an acre or more for a full firefighting effort. It also has ecological benefits that save money compared with other forest restoration methods.

But many forests don't have enough personnel to prepare plans for such fires or to manage them as they burn.

A 2006 report by the Agriculture Department's inspector general said the Forest Service needed 300 more personnel nationwide just to plan wildland fire use programs.

Casey Judd, business manager of the Federal Wildland Fire Service Association, which also represents firefighters, said the Forest Service is having trouble retaining fire experts because its pay and benefits aren't keeping pace with other agencies.

He also said that nationally, the agency has diverted money from fire programs for administrative purposes.

"The (federal) fire program in California is imploding," said Judd. "It's driving our fire chiefs nutty out on the forests."

Mike Odle, spokesman for the Shasta-Trinity National Forest, said his forest has considered wildland fire use but has not finished the planning.

Regardless, he said, the practice would not have made sense under current conditions because fire crews are stretched too thin fighting other fires in the region. "If something were to go wrong with 'fire use,' those resources are already on other fires," he said. "It would not have been smart for us had it been approved on the forest anyway."

Call The Bee's Matt Weiser, (916) 321-1264.