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Chainlink fences were installed next to the creek when the homes were built in the 60s.Many posts have dropped into the creek. The fences make it even harder for residents to maintain the banks.

Multi-agency effort to address Cedar Mill, Johnson Creek flooding
By Mary D. Edwards, associate editor

Cedar Mill Creek used to be a trickle in Lisa Fletcher’s back yard. “It was so tiny, we didn’t even know it was there,” she said of the Evergreen Street home she and her family have lived in for more than 25 years. That’s not the case anymore. For the past several years the creek has grown each rainy season, eating away at her backyard and those of her neighbors.

Many of the trees that line both banks are heavy with English ivy and blackberry vines. They lean precariously toward her and her neighbors’ houses. Huge logs from trees cut somewhere upstream back up water in the streambed. Fletcher, looking down at the fast-moving water one late November day, worries that cracks in the embankment may be precursors to more of her yard sloughing off into the stream.

Fletcher and her neighbors aren’t alone in their concern. A coalition made up of public agencies including FEMA, the state of Oregon, Washington County and local cities, as well as businesses and other organizations, has been formed to look at what can be done to cut down on flooding along Cedar Mill and Johnson creeks. Called the Cedar Mill Creek Flood Remediation Collaborative, the partnership aims to “work together to address flood risks while providing high quality natural habitat within the Cedar Mill Creek and North Johnson Creek corridors.”

Beaver dams may be natural, but they don't help with flooding issues!

The project, which is expected to issue recommendations by summer 2018, is starting with a survey of those who live in the watershed, particularly those who have been affected by flooding in the past 10 years. The survey and project timeline can be accessed at www.cedarmillcreek.org.

Cedar Mill Creek and its tributaries, including North Johnson Creek, drain 5,300 acres from the Tualatin Hills, passing through neighborhoods and parks, around businesses and under roadways, and then join together at the intersection of Walker Road and Murray Boulevard in Beaverton. That area, south of Highway 26, has experienced the most flooding in recent years. Cedar Mill Creek then runs through the Nike campus to join Beaverton Creek in the Tualatin Hills Nature Park, and then the stream eventually join Rock Creek, which drains into the Tualatin River.

On its website, the Collaborative points to 200 years of human impact as the root of the flooding. From the trapping of beavers and removal of beaver dams, logging of the forests and “channelizing” the streams for farming, on to today’s hillside development and roads with their impermeable surfaces—all have led to less land to slow and absorb rain water.

When the storms come, the water pours off the asphalt and concrete in the hills into streambeds that widen to accept the torrent that eventually tears at lower-lying areas like Fletcher’s neighborhood. Apart from the flood of winter 1996, the worst flooding has been in the past five years, she said, adding that dealing with the creek is a bigger job than she and her neighbors can handle.

The bank in Lisa Fletcher's yard has been collapsing for several years. Sandbags aren't preventing the erosion, which threatens her garden shed.

Homeowners and property owners on the creeks are expected to care for the stream and riparian zones that run through their property. Clean Water Services, which manages stormwater drainage and treatment of the wastewater in the Tualatin River watershed, is the agency property owners can turn to for questions about stream care and flooding. It has published streamside care tips to educate property owners on planting and protecting streambanks, and provides a phone number to call in flood events.

As the existence of the Collaborative makes clear, however, efforts to address the flooding haven’t paid off. Gov. Kate Brown, in approving county supervisors’ request to include the Collaborative as an Oregon Solutions project, expressed hope that this time with “all the necessary stakeholders working together … there would be positive results.”

Next steps include gathering more survey information (photos are also requested) and public input through spring 2018. The project team will take into consideration the input, existing regulations, and funding before developing a roadmap and “declaration of cooperation” that will be signed in summer 2018. 

NOTE: The December 12 CPO1 meeting will include a panel of experts to provide solutions to homeowners dealing with this winter’s flooding problems, as we anticipate the longer-term remedies that the Collaborative will provide. See Community News for details.

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