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  • Writer's pictureMark L. Johnson

Water Woes VIII-Water Study Session Report Part A

Hope you had the opportunity to attend or watch (video stream) the Water Study Session on Tuesday. Jing Luo, Marana's new Water Director, gave an excellent update on Marana Water and the water supply/demand situation. We finally got the information requested months ago. Click on the button below to view Jing's PowerPoint Presentation and we will break it down in a two Part Series with Part A below.


Water Study Session Report-Part A

Designated Assured Water Supply (DAWS)

The big item covered in Jing's presentation was Marana Water's DAWS. As a reminder, each Arizona water utility must prove to the Arizona Department of Water Resources (ADWR) that they have a bonafide 100-year water supply, i.e. DAWS. TA has requested DAWS data from Marana for months and now we finally have it. Here is the skinny:

  1. Current Approved DAWS = 7,580 acre-feet per year (AFY)

  2. Actual Water Use (2020) = 2,788 AF

  3. Committed Demand (Platted & Vacant Lots-2020) = 1,988 AFY*

  4. Actual Water Use & Committed Demand (2 + 3) = 4,776

  5. Remaining DAWS (1 - 4) = 2,804 AF

*Note the data presented by Marana Water includes the commercial water demands which is converted to an equivalent residential water use called an Equivalent Dwelling Unit (EDU).

Subdivision Approvals Exceed DAWS

The Study Session presentation did not include a discussion on subdivision approvals but it confirms what TA has been reporting all along. It is included here as it astonishing that subdivisions keep getting approved without regards for DAWS.

Marana uses 0.3 AFY per residential lot to establish water demands. Therefore, there is

Remaining DAWS to serve 9,347 lots (2,804/0.3).

However, the Marana Planning Commission has approved subdivisions (not platted) in the Marana Water Service Area totaling 25,767 lots (from July 2021 Subdivision Activity Report).

This means there are 16,420 lots (25,767-9,347) approved that have no DAWS and the developers are gambling that Marana will obtain additional DAWS in the future.

Existing DAWS Runs Out In 2032

It was reported that Marana can process (platting & approvals) about 835 lots/year. At this rate, existing DAWS will be used up by 2032. See graph from PowerPoint below:

Interesting Factoid

Let's assume that Marana Water had DAWS to cover all the approved subdivisions. Under that assumption, it would take another 20 years (16,420/835) to process all the approved subdivisions! This extends the timeline to 2052! I hope these developers are in there twenties!

This calculation shows how irrational it is to be approving subdivisions well beyond DAWS availability and the ability of Marana to actually process the subdivisions.


In Part B, we will examine some of the future programs Marana Water will undertake to better analyze, plan and be transparent about future water supply and demand.


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