The Upper White River is active and adjacent to three nearby communities, and subject to potential channel migration. The Upper White River Channel Migration Zone (CMZ) study will enable Pierce County to develop an updated zoning map based on science and guide future development away from high-risk areas. The county has completed channel migration studies on the following rivers: Puyallup, Carbon and lower White (2003), Upper Nisqually (2007), and the Greenwater (2017), and South Prairie Creek (2005).
The Upper White River CMZ study is the only remaining CMZ study to be completed in the county. Pierce County is committed to practices (like the CMZ study) that reduce risks to residents, businesses, and infrastructure, while protecting and improving fish and wildlife habitat that rely on our river systems.
For more information on the methodology behind identifying CMZs, please visit Washington State Department of Ecology’s CMZ webpage.
For more information on the different types of channel migration processes and patterns in Washington State, view the Department of Ecology’s Synthesis for Floodplain Management and Restoration, August 2014.
View the Department of Ecology's Flood Hazard Map finder to find the flood hazard map near you.
Pierce County river and flood management
The Surface Water Management (SWM) division of the Planning and Public Works department addresses flood control, water quality and the preservation of natural drainage systems. This helps ensure that Pierce County rivers and streams are clean, healthy and safe, both now and in the years to come.
SWM plans, designs and implements a variety of construction and habitat restoration projects. These projects are identified and prioritized through our Capital Facilities Plan.
Past CMZ studies
Learn more about the SWM division, our current projects, upcoming projects, and more, on our SWM webpage.
Note – all information and updates related to the Upper White River CMZ Study are hosted through this website.
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The CMZ study area supports three nearby communities, which include full time residents, and a variety of seasonal outdoor enthusiasts that frequent the area during the winter and summer months when properties are often filled as short-term rentals. Roughly 50% of property owners live here year round.