Jan. 16 marked the eight-year anniversary of the 2011 flooding in the upper
Sandy River Basin that washed out a section of Lolo Pass Road, undercut the
Zig Zag River bridge, swept away three homes and left a swath of property
damage with over 150 residents stranded by the rampaging waters.

During a Jan. 19 Rhododendron Community Planning Organization (CPO)
Meeting held at the Mt. Hood Oregon Resort, Jay Wilson, resilience
coordinator for Clackamas County Disaster Management, discussed continued
flood risks in the area.

“The Sandy (Basin) is just as capable and dangerous to property in the
future,” Wilson said, citing the historic flooding in 1964 that destroyed 155
dwellings and the more recent 2011 event. “We need to have a policy that
gives us a framework to prepare for an event like this fairly.”

Wilson detailed county plans to request policy development at the state level
regarding Channel Migration Zones (CMZ) and their impact on public safety
and importance for healthy river habitats across the state. CMZ are areas
where river channels migrate laterally over time due to natural processes of
flooding and erosion. This natural movement of the river throughout the
floodplain provides a crucial breeding ground for endangered salmon.

It also provides the potential for highly erosive flooding with risk to property.
CMZ are not currently mapped by FEMA for flood insurance purposes or
regulated for development in Oregon.

Wilson described an increase in flood hazard in the community due to new
development in the CMZ, a continued risk to existing infrastructure and the
need to protect critical salmon habitat as reasons the county is proposing a
statewide CMZ policy. The county seeks a policy that provides a legal basis for
counties to make local land use regulations to limit flood hazards and protect
habitat.

“Current land use policies are allowing people to build in areas we know are
dangerous,” said Clackamas County Commissioner Jim Bernard during the
meeting. “We don’t have a policy in place to address this.”

Bernard, who was joined by fellow Commissioner Ken Humberston, noted that
Oregon disclosure laws are some of the most limited in the country in terms of
making property buyers aware of potential hazards.

“We feel like we should let people know of the potential (flooding),” he added.
Bernard discussed a letter written by the board of commissioners to Oregon
Solutions, an organization that helps local communities develop policy on the
state level, asking for the development of an Oregon CMZ policy group. The
group will be comprised of state and federal agencies with Clackamas County
as lead sponsor and will draft proposed legislation allowing local jurisdictions
to regulate development in areas known for flooding and severe erosion.
“Advisory maps are out there. They just haven’t been officially adopted on a
regulatory level,” Bernard said.

Maps of the CMZ hazard zones on the upper Sandy River were published in
2015 by the Oregon Department of Geology and Mineral Industries (DOGAMI)
using hydrologic surveys conducted with light detecting and ranging (LiDAR)
technology.

“These surveys give scientific basis for informing policies,” Wilson said. He
added they provided a guide for regulatory overlay on a mapped level.
Wilson stated that with county oversight of a state certified CMZ hazard area
there would be restrictions to new and existing development, direction for
bank protection and habitat conservation.

“Standards will be higher and more stringent rather than just the existing
approach,” he added. “We’re trying to think about the next 50 years ... to
insure a balance between natural systems and property protection.”

The Rhododendron CPO meeting marked the beginning of the county’s public
engagement regarding the proposed statewide CMZ hazard policy. Wilson will
present more information about the issue at the upcoming Mount Hood Area
Chamber of Commerce meeting, at 8 a.m. Tuesday, Feb. 5, at the Mt. Hood
RV Village Resort, 65000 Hwy. 26 in Welches.

Additional information about the CMZ and flood hazard is available online at
www.clackamas.us/dm/flooding.html.