Arizona releases interactive subflow zone map for the public

Subflow Zone Locator
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Landowners in Arizona who own wells that pump subflow or who use direct surface water rights face expensive and complicated litigation in what is known as “the water adjudicationOpens in a new tab.” currently involving surface water use within the Gila River and Little Colorado River systems.  As of this writing, surface water rights in the San Pedro River watershed and the Verde River watershed — both part of the Gila River proceedings — are the subject of numerous “contested cases” that are based on information reported in hydrographic survey reports.

For laypeople, a very general concern is if their well is pumping subflow, that means that their well may be taking surface water and they will become parties to the water adjudication.

Well owners worried about whether their wells are located in subflow zones now have a handy interactive tool, thanks to the Arizona Department of Water Resources.

ADWR’s interactive map called “the Subflow Zone LocatorOpens in a new tab.” allows users to type in their well registration number or address to see whether a well is “in the zone” of the proposed Verde River subflow zone or the approved San Pedro River subflow zone.

ADWR writesOpens in a new tab.,

On December 30, 2021 ADWR Adjudications released a subflow zone report for a portion of the Verde River watershed. The report was intended to assist the Court in distinguishing between subflow and other underground water consistent with Arizona law. The report includes maps showing the proposed subflow zone.

The report garnered a great deal of attention. Since the release of the report, ADWR Adjudications has received over 300 inquiries about it, mainly from landowners within the Verde River watershed, an area that includes hundreds of unresolved water-rights claims. By and large, those inquiring property owners wanted to know whether or not their property fell within the proposed subflow zone.

With the assistance of the Department’s IT team, ADWR Adjudications set out to assist those landowners in determining whether or not their properties fall within the proposed subflow zone. Adjudications has posted the fruit of that effort – an interactive map now available on the Department’s website – that allows the public to zoom into the areas covered by the proposed subflow zone.

The map allows the public to see the boundary of the subflow zone laid over a more familiar topo or street map. The map also allows users to enter an address to allow them to more specifically see where the proposed subflow zone is located in relation to their property.

The map includes more than just the proposed Verde subflow zone, however.

It also includes the approved San Pedro subflow zone, so that landowners in the San Pedro River watershed can also see where their property is located in relation to the subflow zone.

Finally, the site also includes a data download of both of the subflow zone maps, so that users with GIS software can access the data. Previously, obtaining these data downloads required the submission of a public records request to the Department.

Access the locator hereOpens in a new tab..


Since 1995, Deborah has owned and operated LegalTech LLC with a focus on water rights. Before moving to Arizona in 1986, she worked as a quality control analyst for Honeywell and in commercial real estate, both in Texas. She learned about Arizona's water rights from the late and great attorney Michael Brophy of Ryley, Carlock & Applewhite. Her side interests are writing (and reading), Wordpress programming and much more.

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Justine Weber
Justine Weber
March 13, 2022 3:24 pm
Very cool resource tool if you have GIS software. Most laypeople will not.

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