Friday, September 25, 2020

Zone A Phase III Floodplain Delineation Study

New Preliminary Flood Maps Provide Updated Understanding of County Flood Risks

The Yavapai County Flood Control District (the District) and the Federal Emergency ManagementAgency (FEMA) are processing a new Letter of Map Revision (LOMR) of several flood hazard areas within Yavapai County. These more detailed maps will help property owners better understand their flood risk and help them make more informed decisions on how to protect their family and property during a runoff event.

Why Remap?

The flood hazard areas in Yavapai County were originally mapped in the late 1970s. Over time, water courses have changed due to large rainfall events, erosion and development. In addition, development over the last several decades didn't always include managing the increased runoff into our watersheds. So, the County’s flood maps are being updated to show the current high and moderate-low flood hazard areas.

High-risk flood areas are shown on flood maps (known as Flood Insurance Rate Maps, or FIRMs) as flood zones beginning with the letter “A” or “AE”. While Zone AE is based on detailed studies that include defining not only the floodplains but also floodways1 and Base Flood Elevations (BFEs)2, most of the County’s original flood studies were based only on approximate studies and therefore, BFEs and floodways were not shown. When BFEs are not available, the burden falls on the permit applicant to determine the true flood hazard area. In some cases, flood insurance could also be less expensive if BFEs were available instead of using approximate Zone A rates.

To help provide this additional detail as well as updated flood risk information, the District started a multi-phase study to remap hundreds of miles of Zone A and include Base Flood Elevations. The updated studies don’t have as much detail as Zone AE studies provide, such as floodways, but they do include Base Flood Elevations, as well as depths and velocities. This data is much less expensive to create and provides information that property owners would otherwise have to determine themselves (or do without when their flood insurance cost is calculated).

What Areas Are Being Updated in Phase 3?

The first phase of updating Zone A flood risk information and providing BFEs included the Big Chino Wash, Kirkland, and Date Creek areas among others. It was part of a bigger mapping study which became final on February 15, 2019.

The second phase kicked-off in August 2015, and covers numerous watercourses including streams and tributaries to Partridge Creek, Skull Valley Wash, and the Hassayampa River. Nearly 145 stream miles representing 90+ creeks, washes, rivers, and tributaries were studied.

This third phase covers Cherry Creek and its tributaries in Cherry, AZ, as well as Cienega Creek near I-17 and SR 169.

The District mailed updated maps to any property owners that have structures on their property as well and LOMA applications to have their structure removed from the flood hazard area prior to the maps becoming effective.

Where Do I Go for More Information?

This web page is the primary source of information about the Zone A-Phase 3mapping project and areas being studied. You can view your property on the new preliminary maps by clicking on the Property Search Tool in the menu at the top of this page. If you want additional details, contact Lynn Whitman (District Director) at 928-771-3197 or email For more information about flood insurance, contact your insurance agent or visit  .

1 Floodway is the land immediately next to the river channel (or other waterway) that is the natural channel for floodwaters. Since the floodway must remain open in order to allow flood waters to pass, construction is typically limited in these areas.
2 Base Flood Elevations are the heights to which floodwaters are anticipated to rise during a major (base) flood, known as the 1-percent annual chance flood. A 1-percent annual chance flood can happen more than once in a year.

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