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Tucson Mountains Unnamed Wash 1 Floodplain Study

Study status:  LOMR approved by FEMA, effective January 24, 2011 

For more information, please contact the Project Manager:
Akitsu Kimoto, Principal Hydrologist
(520) 724-4600
FEMA has approved Letter of Map Revision (LOMR) Case Number 11-09-2711P for the floodplain of Unnamed Wash 1 in the Tucson Mountains. The LOMR became effective January 24, 2011. The Pima County Regional Flood Control District and the town of Marana submitted changes to the Unnamed Wash 1 Floodplains in the Tucson Mountains to the Federal Emergency Management Agency. The revisions start at approximately 1000 feet southwest of Belmont Rd. and extend to the Santa Cruz River. The map revisions are effective as of January 24, 2011. The proposed map revisions reflect better topographic information, revised hydraulic modeling, and incorporates drainage infrastructure. The maps cover portions of Sections 02 and 11, Township 13 South, Range 12 East. If accepted, the revised Floodplains, Floodways, and Base Flood Elevations would modify portions of Flood Insurance Rate Maps 04019C1605K.

Frequently Asked Questions (FAQs)

The most frequently asked questions regarding the re-mapping of the floodplain for the Campbell Wash, the Flood Insurance Rate Maps, Letters of Map Revision, Flood Insurance and more can be found in this LOMR FAQ. The District also has a Flood Insurance page that answers many common questions about flood insurance.

Individual Elevation Surveys

Frequently, published floodplain maps may not reflect whether a residence at the edge of the regulatory floodplain is actually outside to floodplain limits due to map nomenclature issues.  For example the width of a floodplain boundary line on a map at a scale of 1 inch equals 1000 feet may measure 20 feet wide on a printed copy of the map and a residence may be declared in the floodplain by a lending institution even though it may be 20 feet or more above the water surface elevations.  The District identified residences along the edge of the floodplain where additional survey data would clarify of the residence would be impacted by the Regulatory Flood (100-year flood).    Those property owners offered surveys by the District to determine if the residence is impacted by the revised limits.  For those homes that meet FEMA’s qualifications to be removed from the floodplain via a Letter of Map Amendment (LOMA) or a letter of Map Revision based on Fill (LOMR-F).  When appropriate, the District submitted additional data to FEMA to request the residence be removed from the revised floodplain.  The District performed these surveys only with the consent of the property owner.  If accepted by FEMA, a LOMA or LOMR-F occurs sometime after the LOMR is effective. Be aware there are occasions FEMA rejects LOMA and LOMR-F data, therefore property owners should assess the need to purchase flood insurance prior to the effective date of the map revision. For more information contact the Project Manager listed below.


Below is a map of the project area. The map is clickable, so click within a map area or on the map label to get a PDF map showing greater detail. Each map shows the current and proposed FEMA floodplain for portions of the project area. The maps outlined in dark blue highlight the properties on which the floodplain footprint is reduced. The maps outlined in light blue highlight the properties on which the floodplain footprint is shifted or increases.

Clickable index map to access floodplain comparison maps for Tucson Mountains Unnamed Wash 1 LOMR Unnamed Wash 1 LOMR Map #1 Unnamed Wash 1 LOMR Map #2 Unnamed Wash 1 LOMR Map #3 Unnamed Wash 1 LOMR Map #4 Unnamed Wash 1 LOMR Map #5

If you have trouble accessing the maps through the index map above, they are available below.