Longtime Pima County residents are well aware of flooding hazards
in the desert. Many have personally seen the area's normally dry
creek beds become suddenly transformed into raging rivers during
storm events. When flooding occurs,
desert watercourses can overflow their banks and inundate surrounding
areas. Major flows in area watercourses can also severely erode
unprotected channel banks causing significant damage. During recent
flooding events in Pima County some property owners lost buildings and as much
as 300 feet of property due to channel
bank erosion.
Some areas in Pima County are subject to a special kind of flooding
called sheet flooding (PDF format). Sheet flooding is caused when flood water
spreads out over the land surface, rather than running off and
collecting into a defined stream channel. Sheet flooding depths
can reach six inches or more. Since there is often no defined
channel, the path of this type of flooding is highly variable
and unpredictable.
Pima County regulates all unincorporated areas lying within the
100-year floodplain. The 100-year floodplain is defined as the
area adjoining a watercourse that would be covered by water during
a flood event having a 1 out of 100 chance of occurring in any
given year. Of course, floods of differing magnitudes -- smaller
or larger -- could also occur, each with their own probability
of occurring during any one year. An important first step in evaluating
the risk of possible flood damages is to determine whether a property
lies within the 100-year floodplain. Floodplains and channels can change significantly over time, whether due to large flooding events on human alteration of the landscape. A comparison document of the Agua Caliente floodplain from 1960 to 1994 (PDF, 5 MB) illustrates these changes well.
Getting Flood Status Information
There are several methods by which you can obtain county floodplain status information for your property.
- A map of known flood hazards is available. The map replaces the MapGuide In or Out Map, providing information that was previously unavailable. This map shows FEMA and known locally mapped floodplains and regulatory washes within unincorporated Pima County. It is provided for general information only and may not be adequate for permitting purposes. Not all areas subject to flooding are shown on the map. Erosion hazard areas are not shown on the map. The accuracy of delineations, including the delineation of regulatory washes, is not guaranteed.
- Fax Back Service. You can request floodplain status information for a parcel by either faxing or mailing a floodplain status request to us. To process a fax request, you should fill out a floodplain status form (PDF format). To complete your request, simply print out the form, fill in the requested property information, and then fax (or mail) it to us. Copies of the form are also available at the District's offices.
When using our fax or mail service, be sure to include your name, the address of the property and the property tax code or legal description. You should also provide a daytime telephone number in the event we need to contact you for any clarifications regarding your request. Our fax number and mailing address are included on the form. Turn around time for fax and mail requests is typically 5 to 7 working days.
- Floodplain Service Counter. The District also staffs a floodplain service counter located in our offices at 97 E. Congress Street in downtown Tucson. Make sure to visit our service counter to find out if your property is subject to flooding, to determine if you need a floodplain use permit, or for any other flood-related questions you may have. We're located at:
97 E. Congress Street 3rd Floor,
Tucson, AZ 85701-1797
Phone Number: 520-724-4600
Fax Number: 520-724-4621
Please note that the District currently provides flood status information
only for unincorporated portions of Pima County. For similar information on parcels located within the incorporated areas of
the City of Tucson, Oro Valley (PDF request form), Marana, the City of South Tucson,
and the Town of Sahuarita (PDF request form), please check our who to contact page.
Floodplain status information is an essential component of our mission.
The District typically receives between 8,000 and 10,000 requests for
floodplain status information each year.
