Thank you to those of you who provided input!
The final Upper White River CMZ study is now available.
Read the final Upper White River CMZ study (24 MB) (August 2020)
Read the draft Upper White River CMZ Study
The county’s project team, including technical consultant GeoEngineers, gathered physical data (July 2019) and historical data (1913-2017.) This data was then augmented with local information provided by area residents and community groups to analyze the potential future migration of the Upper White River. The study is based on best available science, using the Washington State Department of Ecology’s CMZ study methodology.
Using all available data, the project team has been able to identify potential river migration areas. The figures in the draft report and the below map indicate the severe (red), moderate (orange), and low (yellow) migration potential areas. These zones are determined based on the distance the channel is likely to travel within the next 10, 20, or 50 years. The project team also identified two disconnected migration areas. These areas lie within a migration area but are unlikely to experience migration due to existing human-built infrastructure. In this case, the disconnected migration areas are at Highway 410 near Greenwater at RM 45.
If your property has areas mapped at a severe risk for channel migration, the severe risk area on your property will be regulated as a floodway. Structures located in a floodway may only be restored up to the limits of substantial improvement, if the structure is damaged or destroyed from flooding or channel migration, as set forth in Pierce County Code (PCC) 18E.20.070.
If you currently have flood insurance or plan to obtain it, the severe risk zone will not change your insurance rates. The National Flood Insurance Program does not set policy rates based on erosion hazards. It would pay a flood claim if a structure was damaged in a flood due to erosion.
Properties mapped in a low- or moderate-risk channel migration zone is for information purposes only. The county does not regulate the low- or moderate-risk areas any differently than areas with no identified erosion risks. The low and moderate risk areas represent where the river was calculated to be able to migrate over a period of 50 or 20 years (respectively.)
Once the CMZ study is fully complete and the channel migration and erosion hazard is mapped as severe, moderate, or low, the county will prepare to adopt the study. Once adopted by Council the severe risk areas are then regulated under Pierce County’s floodway codes.
Over the next several months, there will be three additional opportunities to provide public comment before the final report is adopted:
- Planning Commission review
- Council Committee review
- Full Council review
If you would like to be added to the interested parties list, email firstname.lastname@example.org.