Floodplain Management

The Town’s floodplain maps recently went through the Federal Emergency Management Agency’s (FEMA) map modernization program. This program updates maps from a paper product to a digital product with aerial imagery as a background, making the maps easier to read and use. During the course of map modernization, FEMA issued “draft” maps of proposed floodplain changes in Marana. These maps considered the Central Arizona Project Canal (CAP), Interstate I-10 and the Union Pacific Railroad (UPRR) to be levee-like structures. Under FEMA’s change in previous policy, they were requiring levee-like structures to be certified in the same manner as actual levees.  Essentially, these structures were not constructed as levees, do not meet the levee requirements, and the owners of these facilities do not maintain them as levees.

As a result, FEMA’s draft maps would have brought large areas of Marana into an indeterminate Special Flood Hazard Area (SFHA) – including significant areas that had been previously removed from the SFHA by letters of map revision. The affected land included everything between the Santa Cruz River and either the CAP canal or the UPRR from the county line to Ina Road. It is important to note that FEMA had identified these areas as being at risk in the absence of actual study and that the indeterminate nature of their SFHA designation gave no details on the depth of flooding. The Town of Marana disputed this simplified approach by FEMA and with backing from our congressional leaders, map modernization was put on hold in Pima County so that the Town could conduct a large scale detailed floodplain study of the Tortolita Mountain alluvial fan and assess the levee-like structures.  Also at that time FEMA reversed their policy on levee-like structures having to be certified as levees.  FEMA now allows analysis of levee-like structures on a case-by-case basis to determine their effectiveness in affecting floodwaters.  The Marana study helped shape the parameters of how this analysis is performed.

The Town of Marana selected CMG Drainage to perform this large scale drainage study to show the actual floodplain hazards of the entire Tortolita Fan and assess the levee-like structures in the Town limits. FEMA gave the Town until October 1, 2008 to submit the study information. CMG Drainage completed the study and submitted it to FEMA in August of 2008. CMG’s study verified some of the areas FEMA identified as SFHA, but the majority of the original affected area was shown in the Town’s study to not meet the classification of Special Flood Hazard Area. Areas that are not classified as SFHA can and do flood. Flood insurance can be purchased in areas that are not classified as SFHA for more reasonable rates than those that are classified as SFHA. Homeowners may contact their home insurance providers (most of which can broker FEMA flood insurance policies) regarding a “preferred risk policy” for more information.

The final review by FEMA was completed and the CMG study was formally accepted by FEMA on March 30, 2009. With this acceptance, FEMA’s map modernization program was restarted.  An appeal period soliciting technical information and comments started October 16, 2009 and ended January 13, 2010. There was one appeal and three protests to the new mapping.  The appeals and protests were resolved by FEMA on October 7, 2010. The Town received a Letter of Final Determination from FEMA on December 16, 2010 which closed out the mapping process.  The final FIRM was published with an effective date of June 16, 2011. Web-friendly versions of the FIRM are available for viewing below.

As a service to our residents, on March 18, 2011 the Town mailed letters to property owners whose properties were affected by map changes from the 2011 FIRM. These letters provided recommendations for those residents regarding their change in floodplain status and flood insurance strategies. Town staff also participated in publicly advertised workshops regarding the map changes in May of 2011. Detailed information about map changes and flood insurance implications can also be found in a brochure available at the Town Municipal Complex.

The Town of Marana’s floodplain management staff will answer questions as we are able at (520) 382-2600. Town of Marana staff cannot give insurance rate quotes.

2011 Flood Insurance Rate Maps
Below are the links for the 2011 FIRMs. Paper orginials of these maps are available for viewing at Marana Town Hall.
Additional information can be found at the following web links: