Approximately 48,000 acres of Pierce County's 1,070,000 acres is regulated as floodplain. Floodplains are found along our coastal shorelines, valley bottoms, surrounding lakes, and other waterbodies.
While floodplains can be found throughout the county, 95% of the county is located outside of the floodplain. For health and safety reasons, the floodplain is classified into different hazards areas based on the risk of damage to structures and potential for loss of life. Standards for floodways were passed in 1987, until that time there were no regulations to prevent development in these areas.
As our understanding of floodplain management has matured, regulations were developed and put in place to require new development to build in safer areas. As more information becomes available, the areas—which are included within a floodway—will be refined.
Floodways are some of the most dangerous areas of the floodplain.
A floodway can generate erosion forces powerful enough to destroy bridges, roads, and homes. During a flood, the water is deep and/or fast moving enough to sweep a person off their feet or move a car. Because of the risk to life and property, there are significant restrictions on development within the floodway.
To not penalize people who already have homes within the area, the code is written to allow them to live there until such time that their home becomes substantially damaged. Substantial damage is defined as damage which exceeds 50% of a structures value during a five-year period.
Once it is damaged, the home must meet current standards. Options available include moving the home out the hazard area if there is space available on the parcel, the property becomes used for recreational purposes, or other mitigation measures are applied.
Within the county there are 7,800 acres, which falls within one of the three types of floodways: channel migration zone; FEMA floodway, and deep and/or fast flowing water areas. Overall, floodways are 0.7% of the land within Pierce County.
You will find the background and more detailed and technical information of the three types of floodways on the tabs above and to the right under "Information Center".