The Rio de Flag Flood Control Project is a twenty-year effort between the City of Flagstaff and the U.S. Army Corps of Engineers to prevent life/safety hazards and property damage caused by significant flood events in Flagstaff. It is a $122M project with 65% of funding provided by the Army Corps. Construction along the Rio de Flag and Clay Avenue Wash will increase the capacity of the channel and significantly reduce flooding in neighborhoods such as Southside. Project design is in the final stage of completion and the City is in the process of real estate acquisitions. Project scope and benefits include:
Increasing the capacity of the Rio de Flag channel to contain the 100-year storm event
Construction of underground and surface flood way structures
Construction of a composite channel (both above and below ground) in the Upper Reach north of City Hall to provide stormwater surface flow
Realignment of the primary floodway to the south of the BNSF Railway corridor to reduce the amount of stormwater in the Southside neighborhood
Utility relocations, landscaping and re-vegetation, and street reconstruction
Neighborhood stormwater connections will be reconstructed with the project, or planned as future improvements as needed
Once completed, this project has the potential to prevent damage to approximately 1,500 structures in Flagstaff, valued at over $916M. The Project will also remove the probability of $93M in economic damages due to flooding and remove restrictive requirements for floodplain redevelopment.