Project ListProject Map


Project Name: Mesa Zone D Flood Delineation Study


Project Manager: Richard Harris
Contact by phone at (602) 506-4528 or by email

Project is in Supervisor District:

  • District 1: False
  • District 2: True
  • District 3: False
  • District 4: False
  • District 5: False

You can find your Supervisor District by clicking here.

Project Type: Study

Project Description:

The overall study will identify the current Special Flood Hazard Areas for a portion of the previously unstudied FEMA Zone D area in the City of Mesa. 

The study area is approximately 26.1 square miles and is roughly bounded by The Central Arizona Project (CAP) Canal to the east, US 60 to the north, Ellsworth Road to the west and Williams Filed Road alignment to the south. 

Phase 1 

Phase 1 studied the portion north of Elliot Road is currently being reviewed by FEMA as a LOMR request. The study area covers approximately 8.1 square miles. 

Flows in the area generally pass from east to west. Siphon Draw Wash is the primary drainage feature with outflows entering the Phase 1 study area near Elliot Road. The Powerline Floodway flows through the Phase 2 study area, draining outflows from three upstream Flood Control District Dams (Powerline, Vineyard and Rittenhouse dams). Additional flows come from the north, passing under US60, then across Arizona State Land south of the HIghway,  where they eventually collect along Baseline Road and then pass west towards Signal Butte Road. 

Hydrology and hydraulic models for Phase 1 have been developed using topography flown in June 2019.  

Detailed information for study results can be viewed on the Proposed FEMA Floodplain Map For Mesa Zone D Phase 1 by selecting the link at the bottom of this page.

The Phases 2 and 3 will develop these types of models as well. All hydrologic modeling will utilize NOAA Atlas 14 rainfall depth-frequency statistics. 

Phase 2

Phase 2 covers the area south of Elliot Road and north of the SR24 is in progress. Phase 2 extends east to the CAP Canal and west to Signal Butte Road, covering approximately 12.0 square miles. 

Phase 3

Phase 3 will be studied at a later date and will extend from the western boundary of Phase 2 to Ellsworth Road, covering 6.0 square miles.

Last Updated: 2/24/2023 11:53:44 AM

Project Updates

Preliminary Results Available for Review
Posted On: 3/8/2022 3:21:12 PM

There are proposed changes to the current flood maps. They will be submitted to FEMA for review in March 2022.

Review these changes here:

The new mapping will include the following flood hazard zones:

  • Zone AE: An area with a detailed delineation of a floodplain and in which Base Flood Elevations have been determined. A Regulatory Floodway may be part of the delineation. 
  • Zone AO: An area with Flood depths of one to three feet (usually sheet flow on sloping terrain); average flood depths have been determined. For areas of alluvial fan flooding, velocities may have also been determined.
  • Zone X (shaded): Areas of 500-year flood; areas of 100-year flood with average depths of less than one foot or with drainage areas less than one square mile; and areas protected by levees from the 100-year flood. 
  • Zone X (unshaded): Areas to be determined outside the 500-year floodplain.

Public Meetings

There are no public meetings scheduled.

Project Documents

Document Name Description Document Type Filesize Posted On  
Proposed FEMA Floodplain Map for Phase 1 Proposed FEMA Floodplain Map for Mesa Zone D Phase 1 PDF 7 3/3/2022 4:08:59 PM View