Prescribed burns of recent years slowing fire's progress

ALONG THE GUNFLINT TRAIL, Minn. — As the Boundary Waters wildfire continued to burn Thursday, firefighters were thankful for a technique that amounts to fighting fire with fire.

A series of planned, controlled burns over the last five years has been key to minimizing the current fire's reach toward the homes and businesses along the Gunflint Trail, helping so far to avoid evacuations and property damage.

"Those burns were designed to slow a fire down, and they're doing just that," said Mike Martin, a fire information officer who was on a team that worked on a series of the so-called prescribed burns in the last few years.

The size of the Cavity Lake Fire grew only slightly Thursday as winds remained low and humidity high. The fire didn't get any closer to the Gunflint Trail, along which there are dozens of private homes, resorts and wilderness outfitters.

"It was a similar day to yesterday in that we didn't see growth that was very extensive," Martin said.

On July 4, 1999, a massive storm in the Boundary Waters Canoe Area Wilderness left about half a million acres of dead trees in its wake. All that dry wood creates a tinder box for wildfires, and the current blaze started July 14 with a lightning strike in one of those areas, called blowdowns.

Not long after the 1999 storm, forest management officials began assessing how to rid the area of all that fuel. After first clearing out dead trees close to settled areas, the team started larger controlled burns by the end of 2000.

University of Minnesota professor Lee Frelich, an expert in hardwood ecology, said forest officials didn't do enough controlled burns since 1999, but it wasn't their fault.

"For the first few years after the blowdown, it was just too rainy," he said. There were enough resources available, but not enough days when all the weather parameters for a controlled burn were in place. "Mostly it was just bad luck."

He said a burn requires that winds be from the right direction and strong enough to disperse smoke, but not so strong that it whips the fire out of control. If it's too humid the fire smolders, but if it's not humid enough the fire flares up.

The burn also requires a few days without rain before it starts and, obviously, it can't be raining on ignition day. "If you want to be careful with a prescription and not let it escape you have to be pretty strict with the parameters," Frelich said.

Dennis Neitzke, the district ranger for Superior National Forest who first came to the BWCA in 1999 as part of the controlled burn team, agreed it was a complicated process.

"You have a team of 200 people standing by, and when you hit what's called the 'burning window,' you basically say, 'OK, we're going tomorrow morning,"' he said.

Having scouted out fire blockades — lakes and standing trees, mostly — helicopters swoop in and ignite the fires using two methods. One is what firefighters call the pingpong gun, which fires pingpong ball sized canisters of chemicals that explode in flames as they hit the ground.

Some helicopters also have what's called a heli-torch — a drum that squirts out a gel of gasoline and diesel fuel that's ignited by a propane torch, raining waves of fire down on the forest.

Both Neitzke and Martin admitted it can get exciting. "You've got to understand, all wildfire fighters are part pyro," Martin said.

Since 2000, Neitzke said, teams have done prescribed burns on about 37,000 acres of blowdown. Much of it was in areas close to the Gunflint Trail.

That still leaves several hundred thousand acres of standing blowdown, parts of which are now being consumed by the Cavity Lake Fire. And there's still plenty to be consumed — out of an original 1,000 square miles of blowdown, only about 34 square miles have been burned in the last few days.

Locals who live and work along the Gunflint Trail said they're happy now that the prescribed burns were done.

"I think these prescribed burns are really paying off," Cook County Sheriff Mark Falk said Thursday, at a briefing just off the Gunflint. "If not for those we would not be standing where we are today."

The prescribed burns don't stop a fire completely, but rob it of the fuel needed to thrive. Martin said that from a helicopter, you can clearly see the dividing lines between existing blowdown and already-burned areas.

"Once it hits the burned areas, it just sort of smolders," Martin said. "It looks kind of like an extinguished campfire."

With the need to protect the Gunflint somewhat less pressing, firefighters were focusing major efforts Thursday on the northern edge of the fire in an attempt to avoid the political problems of it jumping into Canada.

"That's one of our concerns," said John Stegmeir, the incident commander. "We need to keep that here."

The prevailing winds were from the northwest, which should help. "The Canadians like that," Stegmeir said.

Fire information officer Pam Leschak said wilderness rangers would continue monitoring canoe campers in the sprawling wilderness area. "They are keeping an eye on where the people are," she said. "I know they have escorted a few people out."

About 255 firefighters were working on the ground, from boats and on aircraft, with the number growing daily. Firefighters considered none of the fire to be contained as of Thursday, and had not even made that a priority.

Instead, they were trying to keep it burning west and deeper into the wilderness. "We would be very happy if we could keep it out of Canada and off the Gunflint Trail," Leschak said.

The U.S. Forest Service, which manages the BWCA, has closed 11 of the region's 49 entry points, including connected lakes and portages. Campfires and charcoal-burning stoves were banned in the blowdown area, though gas or propane cook stoves were still allowed.

The BWCA, which covers about 1,500 square miles along Minnesota's border with Canada in what is known as the Arrowhead region, contains hundreds of lakes and rivers and is a popular destination for campers and anglers.

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On the Net:

Superior National Forest: http://www.fs.fed.us/r9/forests/superior