• Mark L. Johnson

Water Woes XIV-Pause On DAWS

The following serves as an update to the previously reported Marana Water Designated Assured Water Supply (DAWS) analysis.


Remember DAWS is supposed to be a 100-year water agency supply, which is approved by the Arizona Department of Water Resources (ADWR).


The data utilized in this analysis came from the Response to two Marana Public Records Requests; (1) Marana Water Service Area Approved Lots and (2) Marana Water Production 2021. The water production data had to be interpolated as Marana would only provide the data in graphical form.


The following terminology is critical:

  • Approved & Platted-subdivision approved by Marana Planning Commission and Town Council and lots are approved for platting and construction as DAWS water supply is available.

  • Approved-Not Platted-subdivision approved by the Marana Planning Commission and Town Council but platting not approved, i.e. construction cannot proceed unless DAWS is available.

The factors used in this analysis come from updated factors provided by Marana Water that were originally used in Marana's 2018 DAWS submittal to ADWR and include the following:

  • Water Consumption/Residential Lot = 0.3 acre-feet/lot

  • Persons/Residential Lot = 2.70 persons/lot

  • Commercial Water Demand = 17% of total water demand

The data is presented in the graphical form below with an explanation of the analysis.

 


Explanation

  1. Current approved DAWS = 7,580 acre-feet/year (AFY)

  2. Current Long Term DAWS Supplies = 4,186 AFY

  3. 2021 Water Production (2,912 AFY)+Platted Vacant Lots (468 AFY) = 3,380 AFY

  4. 806 AFY of existing Long Term DAWS water supply is available which is equivalent to 2,230 Lots (homes)

  5. Groundwater (light green) must be replenished by the Central Arizona Groundwater Replenishment District (CAGRD) and is the only source available when the Long Term DAWS supplies are completely allocated

  6. Are the CAGRD sources Long Term? The Kyle Center for Water Policy at Morrison Institute-Arizona State University prepared a report entitled, "The Elusive Concept Of An Assured Water Supply-The Role of the CAGRD and Replenishment", which questions the long-term viability of CAGRD supplies. CAGRD utilizes some long-term supplies but much of proposed CAGRD supplies are short-term supplies (30 years or less) and non-renewable Long Term Storage Credits (LTSCs) to meet its obligations. This seems inconsistent when a 100-year supply is required to obtain DAWS status.

  7. Marana has approved subdivisions with residential and commercial water demand of 6,227 AFY beyond the current approved DAWS. The residential portion (Approved-Not Platted Lots) is equivalent to 17,228 Lots. Where will the water come from?


 

Conclusions


Marana will be relying on CAGRD replenishment water supplies to meet Approved-Not Platted Lot obligations within its existing DAWS (9,390 Lots) and beyond (17,228 Lots)---unless other hard to find renewable water supplies are secured. But do these CAGRD water supplies really meet the 100-year standard?


Marana needs to ensure that these water supply obligations are permanent so that 30, 50 or 75 years from now there will not be any scrambling to find water when the short term water is gone. The current and prospective Marana Water customers deserve a secure water supply for the duration.