Presentation

City of Mesa — City Council Study Session (2026-02-12)

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Mesa Water 
Resources
Presented by Chris Hassert

Introduction
The 2007 Operating Guidelines for the Colorado 
River expire at the end of this year
The Seven Basin States are working toward new 
Guidelines to start in 2027
Arizona has already absorbed supply reductions
Deeper cuts inevitable to address the supply-
demand imbalance on the River System
Prolonged drought and robust demand have 
contributed to falling reservoir levels
Near term hydrologic projections are not 
encouraging
Every Water Provider is unique and must 
address the challenges before them

On-Project vs. 
Off-Project
"On-Project" area is 
the City Zone and 
served by SRP
"Off-Project" area is 
comprised of the 
Eastern & Southern 
Zones and served by 
Colorado River Water
All areas can be 
supplied with 
Groundwater


Water usage for a Mesa median 
residential customer
6,000 gallons per month
72,000 gallons per year or 0.22 acre-
feet/year
1 acre-foot serves 4.5 median 
residential households for 1 year

1,000 acre-feet serves 4,500 median 
residential customers (households)

1,000 acre-feet serves 3,000 households 
consuming the average demand of 9kgal 
per month
Water Units Refresher

Salt River Project (SRP) 
“On-Project”
SRP Resources
Annual af/yr
SRP Cutover Land (Acres)(1)
21,194
Surface Water Allocation (af/ac/yr)(1)
2.27
Allocation Water Availability =
48,110
Normal Flow Water Availability
14,000
TOTAL SRP Water=
62,110

Central Arizona Project 
"Off-Project"”
CAP Resources (AF/YR)
Full Portfolio
MESA Municipal (M&I)
43,503 
M&I Total
43,503 
SRPMIC Lease (IP)
1,669 
IP Total
1,669 
Wellton-Mohawk (P3)
2,622 
P3 Total
2,622 
RWCD  (NIA)
627 
Hohokam (NIA)
4,924 
NIA Total
5,551 
Available Allocation
53,345

Mesa's Additional 
Water Supplies
Gila River Indian Community 
(GRIC) Water Exchange
New Conservation Space 
(NCS) Water
Groundwater Pumping
Underground Long-Term 
Storage Credits (LTSC)

Gila River Indian Community 
Water Exchange
5:4 exchange of Reuse Water from 
NWWRP, SEWRP & GWRP for CAP water 
delivered at SBWTP or BRWTP
Water obtained through the exchange 
charged at the CAP pumping charge 
($85/AF) opposed to M&I CAP rate 
of ($365/AF) 
Agreement allows Mesa to deliver up to 
29,400 AF of Reuse water to be exchanged 
for 23,520 AF of CAP water
For CY 2026, Mesa's CAP Order accounts 
for 8,128 AF of water through the Exchange
Reuse water that will be delivered through 
the CMRP doubles the volume above

New Conservation Space (NCS)
Roosevelt Dam, completed in 1911
In 1996, a $430M project raised the 
dam by 77 feet to increase storage 
in Lake Roosevelt
Storage increased by 304,729 acre-
feet
Mesa's share of increased storage is 
41,000 acre-feet
In the City's 100-year AWS, ADWR 
recognizes an annual usage of 
12,500 acre-feet
This water can be used anywhere in 
Mesa's service area

Groundwater 
Pumping 
Two types of Groundwater
Assured Water Supply 
Groundwater Allowance
Incidental Recharge
Groundwater can be pumped in all 
parts of the service area
Mesa has 35 active groundwater wells
Pumping could be focused in the 
Eastern and Southern Zones during 
CAP supply reductions
Assured Water Supply Groundwater 
Allowance
AF
2025 Total Demand
98,799 
Annual Incidental Recharge 5.35%
5,286 
Groundwater Allowance
467,895 
Annual Amount
4,679 
Total Annual Groundwater Allowance + 
Incidental Recharge
9,965

Long-Term Storage 
Credits (LTSCs)
Mesa has over 550,000 acre-feet of LTSCs banked 
underground
Three quarters of the stored credits are in the 
Roosevelt Water Conservation District (RWCD) 
Groundwater Savings Facility (GSF)
Granite Reef Underground Storage Project (GRUSP) 
operated by SRP was completed in 1994
Since 2000, Mesa has banked nearly 90,000 acre-
feet of Reclaimed and NCS water at GRUSP
LTSCs are recovered through Mesa's groundwater 
pumping wells
Long Term Storage Credits
af
GRUSP 
88,228
NWUSF
49,710
RWCD GSF
413,033
SRP GSF
4,642
Red Mtn USF
1,470
 Total Stored Credits
557,084
 Total Annual LTSCs 
5,571

0
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Acre-Feet
Off-Project Surface Water Supply vs Demand
GRIC Exchange M & I Priority Water
Total Indian Community Contracts
Subcontract M & I Priority Water
Historical Off-Project Demands
Projected Average Growth Off-Project Demands
Projected Moderate Growth Off-Project Demands

0
10,000
20,000
30,000
40,000
50,000
60,000
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100,000
1983
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2039
2040
Acre-Feet
20% Cut to Colorado River Supplies vs Demand Scenarios
GRIC Exchange M & I Priority Water
16% Cut to Total Indian Community Contracts
20% Cut to M&I Priority Water
Historical Off-Project Demands
Projected Average Growth Off-Project Demands
Projected Moderate Growth Off-Project Demands

0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000
1983
1984
1985
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1988
1989
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1991
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2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
Acre-Feet
20% Cut to Colorado River Supplies vs Demand Scenarios
GRIC Exchange M & I Priority Water
16% Cut to Total Indian Community Contracts
20% Cut to M&I Priority Water
ADWR Groundwater Allowance and Incidental Recharge
NCS Water
Long-Term Storage Credits
Historical Off-Project Demands
Projected Average Growth Off-Project Demands
Projected Moderate Growth Off-Project Demands

Future Supplies 
Long-Term Solutions
Raise Bartlett Dam – $150M for 3,000 
acre-feet per year average
Divert more Reuse Water to the Gila 
River Indian Community
State led Importation Projects selected 
by WIFA
Advanced Water Treatment at 91st Ave 
WWTP – Exchange Water
Septic to Sewer
Continue finding and fixing leaks
Real time leak detection through Smart 
metering

Key Takeaways
The current 20-year Operating Plan for the 
Colorado River expires at the end of this year
Additional Supply reductions will be inevitable 
starting in 2027
Reductions may be introduced in phases
Mesa began building a resilient water portfolio 
a half century ago and continues to add to our 
supplies
Future supplies will be expensive as options 
become more scarce
Water Conservation is a tool that can temper 
future demand

Find fact sheets and more resources online at 
mesaaz.gov/water