As the Mountain community enters the cold and dark season (all while dealing with a pandemic), the 10 year anniversary of the 2011 flood reminds us all that a little warmth at the wrong
time can be a very dangerous thing. Unseasonably warm temperatures
coupled with heavy rainfall and melting snow wreaked havoc in mid-January
2011, causing flooding in the Sandy, Zigzag and Salmon Rivers while leaving
more than 200 people without electricity, water or telephone service, and
necessitating a human chain up and down Lolo Pass Road. Thankfully, nobody
perished in the flood, but three houses were lost.

“It was quite an endeavor,” said Mic Eby, who served as the Hoodland Fire
District Chief at the time and has spent more than 40 years with the district.
Eby noted that the district began preparations for the flood in the days before
and watching the weather reports. He added that the district’s volunteers
came out in force, including members of the CERT group, to help fill and
transport sandbags, provide traffic control, perform welfare checks and more.
“It was amazing how the community came together for that,” he said.
Jay Wilson, Clackamas County Resilience Coordinator, recalled that in the
aftermath of the flood, a town hall was held, featuring all the County
Commissioners and a large crowd of community members.

“It was quite a heated, passionate conversation,” he said. “It was a packed
house.”

Wilson noted that out of that conversation, among many others, it became
clear that members of the community wanted to “fix” the rivers in a similar
fashion to what the Army Corps of Engineers did following the 1964 flood.
“That just became the biggest single issue that our office worked on for the
next five years,” he said, adding that they had to shift those expectations to
help people understand that it was not a case of trying to control the river,
but trying to manage the risk involved with the river.

Wilson explained that when people protect a property with riprap, rock
formations placed to prevent erosion, the hydraulic energy bounces off of it
and creates a slingshot, sending the destructive force elsewhere in the river.
In light of that, efforts have been made to restore the rivers to their natural
floodplains, which takes some pressure off of the homeowners.

“It doesn’t make the risk go away, it just helps to give it more stability,”
Wilson explained, while also noting that fighting a river will also harm fish
habitat.

Wilson pointed to two big projects on the Mountain connecting the rivers to
their floodplains: one completed in 2016-17 upstream of Timberline Rim that
opened a side channel and installed big lumber erosion management
structures (which has already demonstrated that cutting the flow and energy
out of the water does work) and the removal of levees and opening of side
channels at the confluence of the Sandy and Salmon Rivers.

While the 2011 flood helped to shift in this thinking process, the recovery
from the event was different for the county than anything it had done before,
Wilson noted. In the past, the county mostly dealt with permits for emergency
work on properties impacted by flooding, but Wilson described the county’s
efforts in 2011 as being a community recovery facilitator, doing “more
listening than talking” and trying to find common ground through a
transparent public process.

He noted that the county formed an interdepartmental flood recovery group
that met weekly and then bi-weekly for approximately eight years to
coordinate their efforts primarily on the Sandy River flood issues.

The aftermath of the flood also revealed that the county needed a scientific
analysis of the behavior of the rivers to better understand what the best
approach was for policies and programs. The result was a 2015 channel
migration zone study, which Wilson described as the “single biggest
development” resulting from the flood.

“Oregon didn’t have anything like that before,” he said. “This was the state’s
first assessment of that degree.”

The study, which has not yet been formally adopted, came with hazard and
risk maps that identified hundreds of homes on the Mountain that are
currently in imminent threat if a repeat of the 2011 flood took place. Wilson
added that the numbers jump to several thousand homes in imminent threat
if we have another flood similar to 1964.

“That got a lot of people’s eyes open,” he said.

By adopting the hazard and risk maps in that study, the zoning and land use
designations of those areas would change. But Wilson added that there are
complications that have prevented that.

To help share the valuable information, the county has held a “Flood of
Information” event every year (except 2020, thanks to the pandemic) to
provide new information, including a mapping tool that is also available online
(https://www.clackamas.us/dm/channelmigrationzoneresources.html).

Wilson noted that for two years in a row, he met couples at the event that
realized their property was in the channel migration zone, and therefore at a
higher risk, and noted they wouldn’t have purchased the property if they had
known before. But there is no law requiring the disclosure of the risk during
the sale of one of these properties.

Wilson added that people’s perception of risk has changed since the 2011
flood, noting that at some of the public meetings immediately following the
flood, a lot of people expressed interest in the possibility of a buyout for their
property. But after time, fewer and fewer people were interested.

“Unfortunately, I think a lot of human nature is to be reactive,” he said.
Wilson added that the biggest single finding from the 2015 report confirms
that the deck is stacked against homes that are right next to the Sandy and
Zigzag Rivers. That’s because these rivers lie in a volcanic landscape and the
homes are built on terraces that are still unstable, and that doesn’t even
account for climate change causing glaciers to retreat and revealing loose
soils.

“It doesn’t take much to mobilize it,” Wilson said. “Sediment creates erosion
patterns. Anything that brings more sediment into the river, it creates a lot
more uncertainty.”

And despite the magnitude of the 2011 flood and the strong emotions that
followed, the past 10 years have been fairly quiet for flood events, perhaps
creating the appearance that the risk has diminished.

“I think people get lulled into complacency despite all the work we’ve done up
there,” Wilson said.

To make matters worse, Wilson added that should the Mountain community
be impacted by wildfires, the loss of vegetation in the forest would mean a
diminished ability to manage runoff from heavier rainfall.
“If we ever have a fire in the upper Sandy basin, you can bet the jeopardy of
the riverside homes will go up as the river reacts to the new environment,” he
said.

Wilson noted that now is the time to rethink our assumptions about living in a
community with such dynamic rivers. Perhaps instead of property owners
taking what they can get after a home is destroyed, programs that buy out
properties in harm’s way could solve the problem before it arises again, with
the potential for bringing more land into the public domain and providing
greater recreational opportunities on the rivers.

“We’re still working to try and find a way to live with the river, rather than
fighting it,” Wilson said.