Plans for removal of irrigation dam get under way
Grant funding is allowing the planning process to move forward, with removal set for 2013
As part of an ongoing steelhead reintroduction effort, the Crooked River Watershed Council plans to remove an irrigation dam 12 miles downriver from Bowman Dam.
According to Watershed Council Director Chris Gannon, the six-foot-tall, century-old Stearns Dam has thus far slowed reintroduction efforts.
“Stearns is really an important barrier that we need to take action on,” he said.
In addition to the fish passage issues, the structure rests on Bureau of Land Management (BLM) property, but is privately-owned by Quail Valley Ranch. Although the dam was once used as an irrigation diversion, the owner has since chosen to utilize other sites, essentially vacating the structure. Consequently, the BLM would like to remove the dam as well.
“We would like to see the right-of-way no longer being used,” said Jimmy Eisner, fisheries biologist with BLM’s Prineville District. “It would be nice to get that structure out of there.”
At this point, removal of Stearns Dam will still take at least a year to complete. With help from a $71,000 National Oceanic Atmospheric Administration/American Rivers grant and another $38,000 grant from the Oregon Watershed Enhancement Board, the Watershed Council has begun the design phase. So far, they have conducted studies with help from BLM to determine what problems the removal would cause.
“The downriver impacts are primarily attached to the sediment that has been impounded behind this six-foot-tall structure over more than a century,” Gannon said.
A study revealed that the dam holds back around 15,000 cubic yards of sentiment, although the material appears manageable.
“The good news is that it is not real fine sediment like clay-size and silt-size material,” Gannon said. “It is really more of the sand, cobbles, (and) gravels. That is important for us because that’s also the size classes of materials that will help create habitat downriver when we release the sediment.”
Once they remove the dam, the Watershed Council plans to let the sediment travel downriver, work it, and deposit it along the way. While that could improve river habitat, it does potentially create a problem for irrigation district.
For example, the sediment could harm Ochoco Irrigation District’s (OID) head works, where they draw water out of the river.
“What we are wrestling with is potentially in our budget coming up with some contingency funds so that if we have problems with the sediment at any point downriver, we can go out and dredge or remove the materials, so that we don’t create impacts for others that they have to bear the cost for,” Gannon said.
While the increased sediment could harm OID’s head works, District Manager Mike Kasberger still supports the removal.
“The project is part of the steelhead reintroduction, so anything that can possibly make that reintroduction a success, we are in favor of it,” he said. At the same time, OID will do their part to help avoid the damage.
“We have to look out for the best interests of the district,” Kasberger said, “and if the sedimentation can come up and foul the head works, then that is a concern. So, we’re going to sit down and talk with the parties involved and make ourselves comfortable that the procedures used to remove the dam won’t adversely affect the district’s ability to operate.”
As far as upriver concerns go, the primary problem, according to Gannon, is that removing the dam could cause the river to adjust and compromise portions of nearby Highway 27.
“It is kind of a narrow canyon and the state highway runs right along the river,” he said. “That adjustment at the bed load level could mean that the river would start to cut a little bit into that section, and that cutting could undermine the highway and that road bank.”
Gannon anticipates the design phase to conclude around the end of 2012, at which time they will begin seeking permits. If all goes according to plan, they will begin the actual removal around November 2013.
“Our plan and our hope is to enlist the help of the National Guard to use it (the removal) as a demolition exercise,” he said. “The idea is to fracture the concrete in place. We are not trying to blow it out of the river.”
From there, hired contractors will then remove the concrete chunks from the river.