Rio de Flag Flood Control Project

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

Project Potential

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.

Rio de Flag Flood Control Project Video

Southside Community Interviews

Click below to enter the Rio de Flag Virtual Meeting Room

Rio de Flag Virtual Meeting Room

See the latest progress of the Rio de Flag Flood Control Project by clicking here.

Project Updates

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60 percent submittal, concept composite channel improvement plans

Rio de Flag in Picture Canyon - Photo by Bobby Chin, Wikimedia Commons

Rio de Flag in Picture Canyon,  photo by Bobby Chin (Wikimedia Commons)

Rio de Flag in the winter - Photo by Shannon Clark, Friends of the Rio de Flag

Rio de Flag in the winter, photo by Shannon Clark (Friends of the Rio de Flag)