USGS Washington Water Science Center
9722-DRE00 - FEMA Technical Support, Pre-Declaration, January 2009 Floods - Completed FY2009
A wide plume of warm moist air streaming in from west of Hawaii caused widespread rainfall throughout western Washington in early January 2009. National Weather Service flood stages were exceeded in many different basins, most of which drain from the west side of the Cascade Range. Flows at four long-term gages (more than 30 years record) situated on tributary streams recorded new all-time peaks for the period of record. As a result of flooding, a 20-mile stretch of Interstate 5 was closed because of water over the roadway. Thousands of Washington residents in flood-prone areas were evacuated to safety.
The Federal Emergency Management Agency (FEMA), Region X, requested scientific assistance from USGS hydrologists during the flooding. On-site in the FEMA Region X facility in Bothell, Wash., USGS provided important analyses, data, and consultations on hydrologic issues over a five day period. The analyses included the determination of the recurrence intervals, or the statistical frequency of occurrence, of the flows in each of the basins where flooding occurred.