A large wildfire in the Tumalo Creek watershed west of Bend would kill trees and other vegetation and cause erosion. Depending upon the location and size of the fire, it could send enough sediment into Tumalo and Bridge creeks to force the city to stop using them as a water source.
The Bend City Council is poised to decide next week how to treat drinking water from the Tumalo Creek watershed, and one of the key issues is the risk that wildfire could shut down the water source.
The type of membrane filter the city would likely use can remove sediment from the water, whereas an ultraviolet light treatment plant would stop working if there were enough debris in the water. Sediment would block the light and prevent it from neutralizing the microscopic organism cryptosporidium.
City Manager Eric King said that damage from the 1979 Bridge Creek Fire in the watershed still sometimes results in high levels of debris in the creeks.
Ultraviolet light treatment is much less expensive than membrane filtration. According to city estimates, an ultraviolet treatment plant would cost $12 million to $14 million, and the least expensive membrane filtration plant would cost more than $30 million. The city could also build an ultraviolet treatment plant and add wells at additional cost to keep water flowing if the watershed was damaged by fire.
“If wildfire wasn't a threat, we'd choose (ultraviolet light treatment),” King said this week. “But because it is a threat, and there hasn't been much mitigation up there and there's a lot of dead, standing timber, it is a threat.”
The city must begin treating its drinking water for cryptosporidium to comply with a 2006 rule issued by the U.S. Environmental Protection Agency. Bend received an extension to October 2014 of the original 2012 federal water treatment deadline.
The types of forest in this area — lodgepole pines and, at higher elevations, mixed conifers and hemlocks — burn less frequently than ponderosa pine forests, said Fire Management Officer Doug Johnson with the Bend-Fort Rock Ranger District. When wildfire passes through these areas, however, there is greater potential for it to be a severe, “stand-replacing” fire that burns and kills all of the vegetation, including the larger trees.
Fires burn through lodgepole pine forests every 30 to 80 years, Johnson said. Without human intervention, mixed conifer trees at higher elevations in the watershed would burn once every 300 to 350 years.
“We can certainly put (in) an effort, and we do, at minimizing the impacts of fire in the watershed, but I'm never going to guarantee anybody another '79 fire won't come down through the watershed,” he said.
One of the major changes in recent years is that beetles have infested the area and killed many lodgepole pines. “The potential is growing each year, as we're not able to go in and treat any of that area just yet,” Johnson said.
“We've had small fires (in the watershed) we've responded to and been able to suppress,” he added. He estimated three to five small fires start in the watershed each year, and “most of those are lightning-caused.”
The Forest Service also wants to thin trees and complete other fire prevention treatment in the watershed, but has not yet begun the environmental impact review process for such a project.
Prevention, firefighting options limited
The U.S. Forest Service has a limited ability to prevent fires in the watershed because the agency does not want to stir up debris that could wind up in the city's water. Bend currently has an exemption to the requirement in the federal Safe Drinking Water Act that all municipalities filter their surface water. This is one reason most of the watershed is a roadless area.
“We're trying to maintain the quality of that water up there, but there is a price to that and the price is, you know, not having a lot of access up in there,” Johnson said. Federal regulations also prohibit the Forest Service from using fire retardant within 300 feet of any stream or other wet area, so that also limits what the Forest Service can do to slow down flames in the area. The two closest fire lookout towers do not have a clear view of the watershed, so when a storm passes through the area, the Forest Service uses an airplane to check for smoke from fires started by lightning.
“If a fire did get established up there, it would certainly be our No. 1 priority fire,” Johnson said. The only exception would be if the Forest Service had to focus on another fire that threatened lives or property. Due to the lack of roads, firefighters might have to hike a mile or two from their vehicles, Johnson said.
“Without roads to get in and anchor off of, some kind of safe anchor, (fires are) really hard to fight,” Johnson said.
Thinning project discussed
Despite the challenges of trying to prevent a major wildfire in the watershed, the Forest Service and representatives of other interests — other government officials, environmentalists, the timber industry and elected officials — are discussing the concept of just such a project.
The Deschutes Forest Collaborative Project brought together a variety of people to build agreement on how the Forest Service should manage public land, and one issue on the collaborative's agenda is fire in the Tumalo Creek watershed.
Phil Chang, who works on the Deschutes Collaborative Forest Project, said it might be at least another year until the Forest Service begins an environmental review process for any fire prevention project in the area.
“What I think is important about this ... planning area is unlike all the areas that we're focused on for restoration that are lower in elevation, the forest isn't as out of whack,” Chang said. “The probability of the fire starting is not huge, but the consequences of the fire would be pretty significant, both in terms of potential impacts to water quality and also potential impacts to a whole bunch of other values people care about.”
Chang said that on the question of whether the Forest Service should treat the forest to prevent fire in the watershed, people involved in the Deschutes Forest Collaborative Project hold a variety of views. Even among people who believe fire is an important part of the natural forest cycle, some think Tumalo Creek watershed is a unique area that should be protected from a major wildfire, Chang said.
“We definitely are finding this thing where in the environmental community, they are conflicted,” Chang said.
Johnson said Forest Service officials are waiting for the Bend City Council to decide how it will treat city water. If the city begins to filter water, that could help clear the way for a fire prevention project in the forest.
Chang said that during fire prevention work, road construction would pose the largest threat to water quality. “When you do thinning or logging types of operations, the thing that causes the most watershed disturbance is actually the road system,” Chang said.
It is unlikely the Forest Service would build roads as part of any effort to thin the forest. “I don't see us building roads in there,” Johnson said. Crews would do most of the work to thin trees and other vegetation by hand. “It's going to be very, very labor intensive for us, and probably quite expensive,” Johnson said.
Johnson said he can only tell people how often this type of forest typically burns, and there is no way to predict when the next major blaze will occur. That depends too much on factors such as weather. It's up to city councilors to decide how much risk to the water source they can tolerate, King said.
“A lot of that for council comes down to what is the risk of wildfire, and how to mitigate for that risk,” King said. “And what's the best return on investment.”