LA CROIX RANGER DISTRICT— When a prescribed fire goes awry, it’s only natural to ask what went wrong. In fact, that’s a question that officials with the Superior National Forest will be asking …
LA CROIX RANGER DISTRICT— When a prescribed fire goes awry, it’s only natural to ask what went wrong. In fact, that’s a question that officials with the Superior National Forest will be asking themselves in the wake of the 1,015-acre Foss Lake fire, now almost entirely contained.
In most cases, it’s not a matter of laying blame— it’s about learning from every incident. “The end goal is generating a common understanding of what happened,” said La Croix District Ranger Andrew Johnson. “We try to learn what mistakes were made, if any, or what might have been missed, in order to lead to better decision-making.”
While the Foss Lake fire was just ten miles from Ely, it is located in the Superior’s La Croix District, headquartered in Cook, and it was Johnson who made the ultimate decision to proceed with the scheduled burn on May 19, although that decision wasn’t made in isolation. “We have a team of fire specialists who build these fire plans and understand how fire burns in these forest types,” he said. “I rely on their inputs and recommendations.”
Once the fire is out and it’s time to look back, the Forest Service will send in an outside specialist to begin the review, otherwise known as a facilitated learning analysis. “Someone will come in with a fresh set of eyes to look at our data and see what happened,” said Johnson. “They could find that we missed something, or determine it was just one of those things that happens. Either way we really want to know.”
With input from members of the local and regional staff, the review team will thoroughly examine all the planning and related data that led up to the decision to light the fire and provide conclusions and recommendations. “It’s not that there isn’t accountability— there is. But the real purpose is to lead to better decision- making,” said Johnson.
As the Foss Lake fire demonstrates, when mistakes are made, or when weather conditions change unexpectedly, the costs can be high. While the fire burned north into wilderness, and damaged no structures, Johnson said the Forest Service spent $300,000-$400,000 on the initial aerial response alone, which was focused on preventing any fire spread to the east, where it could encroach on Burntside cabins and homes. He said the total bill to control the fire is already well in excess of $1 million, with a final tally potentially as high as $2 million.
Fire planning a long process
In most situations, prescribed fires involve years of planning, according to Superior National Forest spokesperson Kris Reichenbach. The Forest Plan provides a broad picture view of how the Forest Service wants to manage the federal land it oversees. More detailed subsequent planning identifies areas in need of some form of management action, or “treatment” in the Forest Service lexicon. From there, forest managers identify individual stands and decide how best to achieve their objectives, whether through mechanical treatment, like a timber sale, or prescribed fire.
According to Reichenbach, Forest Service managers look at a number of factors in determining how to proceed. While a timber sale is a common method of managing the forest, it doesn’t always meet the “prescription” in every case, said Reichenbach.
“If we’re looking to regenerate jack pine, encourage blueberries, or reduce fuels, fire is usually the only good means of achieving that,” she said. “For certain species, mechanical treatment won’t get the most desired outcome.”
The original plan for a 78-acre fire near Foss Lake was part of a larger complex of prescribed burning along the north and west side of Burntside Lake, primarily intended to reduce fuel loading from blowdown and standing dead balsam fir, killed in recent years by a combination of drought and spruce budworm. Forest Service managers had determined that the fuel loading, much of it within the relatively inaccessible Boundary Waters wilderness, posed a particular risk to homes and cabins along portions of the north shore of Burntside Lake.
Fire officials had already completed much of the burning along the North Arm of Burntside and the Foss Lake treatment represented a continuing shift to the west. Given prevailing winds, fires in Minnesota most often burn roughly west to east, so fire officials intentionally opted to reduce fuel levels on the eastern end of the Burntside treatment zone first, so that any escaped fires to the west would pose less risk to residences in the area.
The Foss Lake burn was, similarly, a building block to a much larger prescribed burn, near Crab Lake, tentatively scheduled for this fall. Much of the Foss Lake fire burned into areas that were part of the planned Crab Lake burn.
While most prescribed burning goes off relatively smoothly, Forest Service officials acknowledge there’s always a level of risk. And that’s why every fire has a long list of criteria that must match before fire officials give the order to light it up. “Our people really work hard to come up with the optimal conditions for a particular site,” said Reichenbach. That includes the right weather, which is always a balancing act. Too wet or too calm, and the fire won’t burn well enough to achieve the objective. Too dry and windy, and the fire can quickly jump containment lines, as happened at Foss Lake on May 19.
“Our fire managers also look at available resources, to be sure we have contingency forces in place,” said Reichenbach. Given the dry conditions in May, the Forest Service had both air tankers and a Chinook helicopter stationed at the Ely airport, which allowed fire officials to respond quickly when the Foss Lake fire jumped the lines.
Fire officials closely follow weather forecasts, often days and weeks in advance as they look for the right conditions to achieve their objectives. The Forest Service issued a press statement early on Thursday notifying the media that weather conditions were favorable for the Foss Lake burn and that the ignition could come that afternoon.
One of the key factors that officials were looking for was a south wind, said Johnson. While some wind is critical to achieve the desired fire growth, officials look for wind directions that will tend to take the fire away from structures or other potential hazards should it escape its boundaries. The Foss Lake burn unit was located just south of the wilderness boundary, so the south wind was expected to push the fire into the wilderness, where risks to property were significantly lower.
Forest Service officials rely on specially prepared fire forecasts from the National Weather Service, which can project spot weather conditions for almost any location. The Weather Service’s initial forecast, issued for an 11 a.m. fire ignition on Thursday, projected that south-southwesterly winds would increase to nine miles per hour, with gusts to 14 by 2 p.m. It also forecast relative humidity, a critical factor in fire activity, at around 23 percent. That’s low for Minnesota in the spring, but it wasn’t enough to generate a red flag warning. In either case, the forecast put the conditions within the parameters that the Forest Service had determined would allow for a successful, and safe, burn.
Forest Service burn crews monitor weather conditions at the fire scene with a portable weather station so they can quickly know if conditions are moving towards a higher level of danger. And shortly after the fire crew began ignition, at around 1 p.m., that’s exactly what happened, according to Johnson. “The relative humidity dropped and it dropped fast,” he said. “And the winds grew increasingly gusty.” The fire crew likely could have handled either one of the changes by themselves, said Johnson. “But when both indices go the wrong way, you would expect to see a pretty dramatic increase in fire behavior.”
With the southerly wind, the fire crew started the fire near the north end of the planned burn. “We prefer to back the fire into the wind,” said Johnson.
But shortly after ignition, when the fire was first taking off, a spark landed to the north of the containment line. “It was the worst possible place,” said Johnson, noting that the ember landed at the base of a steep, rocky slope peppered with dead and bone-dry balsam fir. The fire caught, headed up the slope, and was quickly racing to the north into the Boundary Waters.
Whether the Forest Service misjudged the weather forecasts, or whether the forecasts were flawed remains to be answered by the subsequent incident review. The readouts from the portable weather station set up by the Forest Service weren’t available as of presstime. An afternoon forecast issued by the Weather Service reflected only a minor change in wind gusts, to 17 miles per hour, with no change in the overall wind speed. The forecast did push estimated relative humidity down significantly, from the 21-26 percent range to 15-20 percent.
While the Foss Lake burn went awry, Forest Service officials note that careful planning did prevent the subsequent wildfire from doing much damage. Previous burning had reduced fuel loads in the populated areas to the east of the fire. While weather conditions weren’t exactly as forecast, the wind direction did keep the fire restricted to the wilderness. And, because the planning included having contingency resources nearby, both air tankers and heavy lift Chinook helicopters were just minutes away in Ely and quickly and effectively responded to the fire.
Even when fire conditions took a turn for the worse over the next several days, fire crews were able to keep the fire from spreading much beyond its initial Thursday run. Meanwhile, the crews worked quickly under difficult circumstances to construct fire line around the entire burn.
“We’re amazed at the progress the crews have made,” said Johnson. “And the rain didn’t hurt.”
Update: As of Thursday morning, the Forest Service declared the Foss Lake Fire to be 95 percent contained. It also submitted an updated acreage estimate, at 936 acres.