While the flood in January 2011 wreaked havoc on many homes and streets on the Mountain, one population got a reprieve from the rushing waters: steelhead and coho smolt. Thanks to stream restoration work performed by the U.S. Forest Service, Portland Water Bureau and other agencies with the Sandy River Basin Partners, the juvenile fish had safe havens to get through the high water.

“It really dispersed the flood,” said Greg Wanner, supervisory fish biologist at
the Zigzag Ranger District, particularly noting the work done near The Resort
at The Mountain “With all the wood there it really protected a lot of the side
channels and islands (and) fish used them to get out of flood waters. It’s a
phenomenal success story.”

In the past 10 years, the SRBP has activated historical side channels, infused
streams with woody debris and restored fish habitat in an attempt to help
coho and winter steelhead populations recover after being listed as a
threatened species. The organization is now at the beginning of a 20-year
study of the coho and steelhead smolt, which began in 2009
“We’re investing a huge amount of money to restore rivers up here,” Wanner
said. “This is one of our best tools to show how good we are doing.”

History
After a flood event in 1964, the Army Corps of Engineers straightened
portions of the Sandy and Salmon Rivers and removed wood to increase water
conveyance.

“As we all know, that wasn’t the right approach; you want the floodplain, you
want the rivers to enter active floodplains ... because the water has more area
to disperse,” Wanner said.

Starting in the 1970s, some biologists began to reintroduce some wood into
the streams to return it to its natural state, but they only added simple
structures, some of which would be easily moved by high water.

Things gained momentum with the formation of the SRBP and really got going
with the removal of Marmot and Little Sandy Dams in 2007. The SRBP first
prioritized the Salmon River and Still Creek for the restoration work, with
much effort concentrated into the Salmon River in the past six years.

Smolt leave their river homes to head out to the ocean based on the river
temperature and discharge. While smolt that originate further downstream
leave their homes earlier, rivers on Mount Hood typically see the peak of
steelhead departures in early May and the peak of coho departures in late
May (sampling occurs from the first week in April until the last week of June).
Biologists capture the fish with rotary screw smolt traps, large metal devices
featuring a spinning basket that direct fish into a live well at its rear and fixed
in the stream by cables. Once a day, biologists check the trap, sort and count
the fish and record fish data, including weight, length and the general health.
Fish are then marked with paint or a fin clip and returned at least a quarter
mile upstream.

When recaptured, the marked fish are then used to perform population
estimates and to see how productive the streams are.

Wanner noted that the study is in the early stages – approximately three
years in – and it cannot be known how successful the stream restoration work
has been, but there have been some trends he’s noticed.

“The Coho in Still Creek are the fattest in the basin; there must be a lot of
food and good rearing habitat up in Still Creek,” said Wanner, adding that the
Bull Run River and Little Sandy River feature some of the better areas for
steelhead, while the Salmon River produces the most fish of all the area
tributaries.

And since coho return to their freshwater homes to spawn after three years in
the ocean, and steelhead take up to six years to return, it will take a few more
years before the picture gets any clearer.

Wanner also noted how environmental factors, such as drought or flood, can
impact the fish population.

“It’s going to take about 20 years to get a really good data set because you
have to include those environmental factors,” Wanner said.

* * *

Next month: an update on stream restoration work being done on the Salmon
River and Still Creek.