Levees are earth structures that keep elevated waters from flooding interior lowlands. Yakima County has 21.8 miles of levees. 15.1 Levee miles are certified by the Army Corps of Engineers for different flood level events, and are maintained per Corps requirements, while the rest are orphan levees that have no certification.
8.6 miles of Authorized Federal Levees
6.5 miles of PL84-99 Certified Levees
6.7 miles of Non-Certified "Orphan" Levees
City of Yakima and Terrace Heights are protected to 100 year flood event
Disrupted river processes
River attack at constraints
Reduced area for sediment deposition
PL84-99 Project Maps: Non-Federal Levees Systems in the Federal Program
Levee Owner’s Manual for Non-Federal Flood Control Works
The Levee Owner’s Manual (PDF) for PL84-99 was written specifically for the public sponsors of non-Federally constructed levees, floodwalls, channels, and other Flood Control Works. It describes the proper operation and maintenance of these structures, and the assistance the U.S. Army Corps of Engineers can provide before, during, and after a flood.