Contact Information
Community Relations
Carol Brichta
Program Manager
Department of Transportation
(520) 724-6442
email: Carol Brichta
Project Planning
Stephen Wilson
Civil Engineering Manager
Department of Transportation
(520) 724-5912
email:
Stephen Wilson
Final Design
Nancy Cole
Director Capital Program Office
Department of Transportation
(520) 724-6312
email: Nancy Cole
Meeting Notices
Open House - March 31, 2020 - Cancelled
Floodplain Mapping
A Conditional Letter of Map Revision (CLOMR) application has been submitted to the Federal Emergency Management Agency (FEMA) to reflect changes to the Rillito Creek floodplain associated with the proposed Sunset Road Bridge over the Rillito Creek that will connect River Road to Interstate 10. The project will modify the Flood Insurance Rate Maps (FIRMs) for Pima County and the City of Tucson. The FIRM panels impacted are 04019C1660 L, 04019C1666 L and 04019C1667 L.
The regulatory floodplains on the FIRMs are designated as Special Flood Hazard Areas (SFHAs), which are areas that have 1-percent chance of being inundated in any given year. The FIRM maps also show a floodway, which is the portion of the floodplain that must be reserved for the regulatory flow. FIRMs are used to determine if flood insurance is required for federally backed mortgages. The FIRM maps are also to help assist communities with floodplain management.
Each of the three maps linked on this webpage show three floodplains. The imagery on the maps are as follows:
- The areas highlighted in LIGHT and DARK BLUE represent the Special Flood Hazard Areas (SFHAs), which are areas that would be inundated with water from a flood event that has a 1% probability of occurring in any given year.
- The BLUE areas covered with FINE RED DOTS reflect the floodway.
- The areas in GREEN represent areas that would be inundated with water from a flood event that has 0.2% probability of occurring in any given year.
- The BLUE NUMBERS represent the Base Flood Elevations in feet above sea level.
The first image on each page reflects the current or Existing FIRM mapping.
Map 1 of 3
Map 2 of 3
Map 3 of 3
It is important to note that watercourses and watersheds change overtime and, since 2011, floodplain modeling and mapping standards have changed. This has led to the creation of the corrective effective conditions floodplain model.
The center image reflects the Corrective Effective Conditions and illustrates what the floodplain would look like if it were remapped today without the proposed bridge. The pre-bridge analysis indicates that the Rillito Creek could breakout to the north at the Camino de La Tierra Road alignment (LIGHT BLUE area). There are four privately owned properties where the floodplain limits extend slightly past the property lines under the current conditions; no homes are impacted. The majority of the breakout flow would impact publicly owned land and rights-of-way. There is an additional breakout in a drainage channel further north where the flow is contained within the channel.
The image on the right reflects the Proposed Conditions, which represents the floodplain changes to the Rillito Creek with the proposed Sunset Road Bridge. When you compare the water surface elevations from the Corrective Effective Conditions to those on the Proposed Conditions, you will see the maximum increase in the regulatory base flood elevation is about one foot just upstream of the proposed bridge. The image also shows an increased width of the floodway by approximately 180 feet, 600 feet downstream of the proposed bridge. The final floodway will be contained within the soil cement bank protection.
There are two structures adversely impacted by the increased water surface elevation by the proposed bridge. Those are two greenhouses owned by Pima County that will be removed or relocated. There are no other structures impacted by increased water surface elevations under the proposed conditions.
Once the project is completed, a Letter of Map Revision (LOMR) request will be submitted to FEMA to revise the water surface elevations and FIRM SFHAs and the floodway. Please see the attached brochure for the most frequently asked questions about LOMRs.
If you have any questions regarding the FEMA mapping process for this project, contact the Pima County Regional Flood Control District at (520) 724-4600 or email the District at RFCD@Pima.Gov.