Chehalis Basin Strategy progress in review: Log jacks protect wastewater treatment plant in Grays Harbor County


More than 130 local fish and flood projects have been completed across the Chehalis River, Basin coordinated and funded through the Office of Chehalis Basin (OCB).  

The OCB board is composed of local officials as well as tribal and environmental representatives. 

These projects are done in cooperation with the Chehalis River Basin Flood Authority, local governments, tribes and the Aquatic Species Restoration team. Together, these projects are part of the Chehalis Basin Strategy to restore aquatic species and to reduce flood damage for families and communities.

This article is part of an ongoing series highlighting projects that have been completed in the basin.  The Chronicle has partnered with the Office of Chehalis Basin for this series. 



Over the course of 2018 and 2019, more than 220 “log jacks” were placed in front of the Montesano Wastewater Treatment Plant (WWTP) to:

• Protect the treatment plant from the oncoming Wynoochee River.

• Prevent the treatment plant’s catastrophic failure from the river undermining and toppling the facility and preventing a public health and environmental disaster from raw sewage being dumped on downriver communities such as Cosmopolis and Aberdeen and tribal lands.

• Buy time by prolonging the plant’s operational life.


The problem

In the mid-2010s, basin residents were at risk of being exposed to sewage sludge because flooding and riverbank erosion were threatening the wastewater treatment plant in Montesano.  By 2017, it became clear that the Montesano WWTP was substantially threatened with catastrophic failure due to the continuing eastward migration of the Wynoochee River toward the city’s treatment plant.

• The Wynoochee River was steadily migrating eastward about 17 feet per year toward the treatment plan to the point where the river was beginning to work its way around the plant, threatening to encircle and topple the facility.

• Existing sheet pile wall and riprap protection measures were failing to the point where they were in fact exacerbating erosion and scour at the plant. Sheet pile wall had scoured out to a depth of minus 35 feet, significantly beyond the original design of no more than minus 25 feet.

• The city lacked the financial resources necessary to move the treatment plant. These kinds of facilities take years — decades even — of planning and capital investments to move.


The project

The project included constructing and installing more than 220 log jacks through 2018 and 2019 construction seasons to prevent further eastward migration and undermining of the wastewater treatment plant by the Wynoochee River.

• Log Jacks are an innovative, “bioengineered” streambank protection method that mimics natural processes and enhances aquatic habitat while minimizing typical “hard armoring” techniques such as sheet pile and riprap.

• This was a collaborative project involving local, state, federal and tribal agencies, which worked in tight timeframes within their authorities to develop and implement a cost-efficient, timely, permit-friendly and effective solution.


The impact

City and downstream communities can breathe a sigh of relief knowing an immediate environmental, public health threat has been averted and that there is now more time to plan for the future.

• Millions of dollars in emergency, cleanup and replacement measures have been averted — upwards of approximately $40 million — for relatively low cost, approximately $2 million.

• The river is moving away and the riverbank is growing.

• Habitat complexity has increased with more nooks and crannies for juvenile fish, river otters, vegetation and sediment deposition.

• Life of the WWTP has been extended by 15 to 30 years.


Thoughts on project

• “Back in 2018, the Wynoochee River that runs behind this plant was eroding at around 17 feet a year. The innovative project that occurred here protected the city of Montesano’s wastewater treatment plant and prevented a massive disaster for public health and safety, as well as a disaster for fish and wildlife.” — Montesano Mayor Vini Samuel 

• “If we chose to do nothing, the wastewater treatment plant would have washed away and would have ended up polluting the Wynoochee River with millions of gallons of raw sewage downstream into Aberdeen, as well as the tribal lands causing a pretty significant ecological disaster.” — Samuel 

• “I’m super impressed with what the local community in the harbor is doing for a variety of reasons. Number one is super collaboration. Everyone is working together from landowners, the Department of Ecology, to local mayors. Number two, people are making decisions based on science, not mythology, not ideology, just science. Third, we’re doing good things for economic development, which we know is so critical in the harbor. When you make infrastructure investments, you’re building jobs.  From soup to nuts, the Harbor is doing some great work, so it’s been a good day.” — Gov. Jay Inslee

About the Chehalis Basin Strategy

The Chehalis Basin Strategy is a network of partners and projects dedicated to protecting communities from flood damage, restoring critical habitat for aquatic life and ensuring the Chehalis Basin is safe and prosperous for people, fish and wildlife, for generations to come.

The strategy, through the Office of Chehalis Basin, has invested nearly $152 million in on-the-ground flood preparation, flood damage reduction and aquatic species restoration, and has completed more than 130 projects, with dozens more underway, across the Chehalis Basin.

The strategy is led by a group of representatives with diverse interests and perspectives called the Chehalis Basin Board, and is administered and funded by the Washington Department of Ecology’s Office of Chehalis Basin. It depends on its many partners and collaborators across the Chehalis Basin and the state, such as the Chehalis River Basin Flood Authority, to inform the path forward and take projects from ideas to reality.


— Source: Office of Chehalis Basin