This article was published on: 09/20/15 12:00 AM
12-mile swath runs from Todd Lake to Three Creeks Lake
By Scott Hammers
The Deschutes National Forest has begun constructing a 12-mile fire break east of Bend, intended to halt wildfires from moving from the Three Sisters Wilderness into the city’s Bridge Creek watershed.
The watershed supplies the surface water portion of Bend’s dual-source water system. Water drawn from Bridge Creek near Tumalo Falls runs though pipes to a facility just west of Summit High School, where it is treated and pumped to Bend residents’ homes.
The 50-to-200-foot-wide swath would run from near Todd Lake to Three Creeks Lake, following Forest roads 370 and 4601.
Jean Nelson-Dean, public affairs officer with the Forest Service, said a fire break in the area has been a priority for several years.
The Pole Creek Fire of 2012 showed how such a break could be helpful, she said.
“There was concern during that fire — and fortunately, it didn’t happen — that (it) was going to move over and go right into the watershed, which could potentially impact the Bend watershed for years.”
Patrick Griffiths, water resources manager for the city, said wildfire can generate large amounts of sediment that infiltrate surface water systems by eliminating the organic material that serves as a natural filter.
“When you take away duff, the tree canopy, the needles on the trees, you allow rainfall to come in and move sediment that used to be anchored by vegetation,” Griffiths said. “Once you remove that vegeatation layer, that soil unwinds pretty quickly.”
Griffith said even today, the city’s water system takes in sediment due to the damage done by a 1979 fire that burned much of the area surrounding Tumalo Falls.
Nelson-Dean said contractors working for the Forest Service will thin trees and mow down brush along the fire break, but will not clear cut the area. Sisters Forest Products LLC is currently clearing dead trees from 172 acres of the project.
Mechanized equipment is not permitted in wilderness areas, making it difficult to reduce the fuel load that can contribute to explosive fires.
Nelson-Dean said although the fire break would also serve to keep fires that began in the watershed from moving into the wilderness area, protection of the watershed is the primary goal of the project. The partially cleared swath will also create a safe space for firefighters combating any future fires in the area, she said, recalling a recently thinned area that was used in similar fashion during the 2014 Two Bulls Fire.
The city is also in the process of installing a new filtration system for its surface water intake, a membrane-based system that can deal with heavier sediment loads. The city rejected a system that uses ultraviolet light to kill microorganisms that can cause illness, but does not address larger particles that can find their way into the water system.
Griffiths said because it is impossible to eliminate the risk of fire in and around the watershed, the combination of the fire break and the membrane filtration system will serve as a “belt and suspenders” approach to assuring the surface water system can produce usable water for city residents.
Users of the Metolius Windigo Trail and the Mrazek Trail may encounter crews working on the fire break project when crossing Forest Road 4601.
Work on the project is expected to continue through 2018, with most work conducted during the fall and spring.
— Reporter: 541-383-0387, shammers@bendbulletin.com