Chehalis River Erosion Could Threaten Montesano Water Treatment Plant

MONTESANO, Wash. – The city of Montesano is more closely watching an eroding bend in the Chehalis River near Mary’s River Lumber, Mayor Ken Estes toured the area last week “We were able to see that the years, or maybe even centuries of the buildup of silt that created the oxbow are now being washed away – apparently caused by as the tide comes in the ground becomes saturated, when the tide goes out it starts ‘sluffing’ off.”
Estes told his council at this week’s meeting, erosion has cut the bend in the river from 1,000 to just over 100 feet wide near the mill along State Route 107 “Without any action by man, the oxbow will erode through in the next few years, or in the next major flood like the one in 2007. The result would be like a firehouse stream directly into Mary’s River.”
The city is concerned that the river could blow through the lumber mill and go straight for their wastewater treatment plant across State Route 107. Estes said all options are being explored, including reopening of the relic channel closed in the 1940’s. The city contracted Parametrix to draft some solutions through a Flood Authority grant late last year.