Presentation

City of Mesa — City Council Strategic Planning Session (2026-09-17)

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Mesa's Water Supply Update
Preparing Today for Tomorrow's Water Needs
City of Mesa Water Resources Department
Presented by: Joe Giudice, 
Jesse Heywood and Nicole Petker

PURPOSE OF TODAY'S DISCUSSION
Focus: drought on the Colorado River System and the primary reservoirs — Lake Powell and Lake Mead.
Federal actions
Record of Decision and Final EIS
2027–2028 operating rules
What rules now apply?
≈Mesa implications
Mesa water supplies
How supply reductions affect Mesa
Future investments
How Mesa continues preparing
Photo Credit: UNLV
Mesa Water Resources
The Decline of Lake Mead
Review of Portfolio
1

Mesa Water Resources
Mesa’s Water Portfolio Has Evolved Over Generations
From foundation supplies to an integrated, diversified water portfolio
≈
1900s–1960s
SRP + 
Groundwater
Local surface water 
and groundwater 
established Mesa’s 
municipal system.
+
1970s–1990s
CAP Added
Colorado River water 
broadened Mesa’s 
regional supply 
portfolio.
↓
1990s–Today
Recharge + 
Storage
Mesa expanded 
underground 
storage, and 
recovery capacity.
Today + Tomorrow
Reuse + 
Exchanges
Reclaimed water and 
partnerships add 
flexibility and extend 
existing supplies.
Increasing Diversity  •  Greater Flexibility  •  Long-Term Reliability
2

Mesa's Water Portfolio
INTEGRATED RESOURCES SUPPORT LONG-TERM WATER RELIABILITY
Surface Water
85%
≈
Salt & Verde Rivers (SRP)
40%
≈
Colorado River (CAP)
45%
Groundwater
6%
Recharge • Storage • Recovery
↓
Reclaimed 
Water Exchange
9%
Reuse • Sustainability • Partnerships
Mesa Water Resources
3

Strategic Water Resources Beyond the Core Portfolio 
❖Gila River Indian Community 
(GRIC) Water Exchange
❖New Conservation Space (NCS) 
Water
❖Groundwater
❖Underground Long-Term Storage 
Credits (LTSC)
❖Arizona Water Bank
Reuse + Exchange Infrastructure
Central Mesa Reuse Pipeline / GRIC Exchange
New Conservation Space
Roosevelt Dam and SRP storage
Groundwater
Production and recovery well capacity
Banked Water Credits
Recharge and long-term storage
Mesa Water Resources
4

On-Project vs. 
Off-Project
• "On-Project" area is 
the City Zone and 
supplied by SRP
• "Off-Project" area is 
comprised of the 
Eastern & Southern 
Zones and supplied 
by Colorado River 
Water
• All areas can be 
supplied with 
Groundwater
5

Mesa Water Resources
↓
!
6

The Colorado River has changed
Current system status
Lake Mead
27%
Lake Powell 23%
1
Reservoir levels remain low
Lake Mead and Lake Powell continue to carry the 
effects of long-term system imbalance.
2 Near-term projections remain challenging
Continued dry conditions and high demands keep 
pressure on reservoir operations.
3 Record of Decision and Operating Guidelines 
8-21-2026
Post-2026 guidelines will shape Colorado River 
operations beginning in 2027.
4 Arizona has already absorbed reductions
Future actions must account for prior 
conservation and impacts to CAP users.
Planning implication: Mesa must continue preparing for less certainty in 
Colorado River supplies.
Source: Central Arizona Project Colorado River Conditions Dashboard; user-provided current conditions graphic.
7

Federal Response: Post-2026 Timeline
June 2023
Notice of 
Intent to 
prepare EIS
October 2023 
Scoping 
Summary 
Report and 
Federal 
Register Notice
January 2025
Released 
Alternatives 
Report
January 2026
Published 
Draft 
Environment
al Impact 
Study
July 2026
Published 
Final EIS
August 2026
Adopted 
Record of 
Decision and 
issued 2027–
2028 Operating 
Guidelines
Fall 2026
Finalization 
of parallel 
agreements
With no seven-state consensus on long-term operations, Interior established a federal framework and 
near-term operating rules while Basin negotiations continue.
Source: Arizona Reconsultation Committee August 24, 2026 Meeting user-provided current conditions 
graphic.
8

What the Federal Decision Does
10-Year Record of Decision
2027–2036 Decision Framework
Planning implication: Mesa must continue preparing for less certainty in Colorado River supplies.
• Establishes operating principles, thresholds and 
ranges for managing Lake Powell and Lake Mead 
through 2036
• Operating rules established in two-year increments
• Lower basin shortage up to 3 MAF per year
• Coordinated reservoir operations 5-12 MAF to protect 
critical infrastructure at Glenn Canyon Dam
• Lake Powell is expected to begin Water Year 2027 in 
the Lower Elevation Infrastructure Protection Range, 
with an initial release range of 6.0–7.0 MAF
• No Upper Basin imposed reductions and discretionary use of Reservoirs
• Allows future seven-state consensus agreements to be incorporated
9

2027–2028 Operating Guidelines
Planning implication: Mesa must continue preparing for less certainty in Colorado River supplies.
•1.25 MAF annual Lower Basin reduction
•At least 700 KAF additional Lower Basin conservation now through 2028
•Lake Powell operations focused on maintaining 3,510 feet for infrastructure reliability
Arizona
California
Nevada
Total Lower 
Division States
2027
760 KAF
440 KAF
50 KAF
1,250 KAF
2028
760 KAF
440 KAF
50 KAF
1,250 KAF
Total Reductions 
2027-2028
2,500 KAF
Additional Conservation 
2027-2028
300 KAF
300 KAF
100 KAF
700 KAF
Total Reductions and 
Conservation
1,820 KAF
1,180 KAF
200 KAF
3,200 KAF
10

Planning implication: Mesa must continue preparing for less certainty in Colorado River supplies.
2027 Operations: Federal Impact of Lower Basin Reductions
Estimated cut to M&I Priority is 14%, Indian Priority is 10%, and 100% to NIA Priority. 
MESA CAP PORTFOLIO
53,345 AF
Full allocation
→
≈41,537 AF
Estimated after reductions
−11,808 AF
22%
78% remains
22% reduced
CAP resource
Full
2027–28
Impact
Mesa M&I Allocation
43,503
37,413
−14%
SRPMIC Lease Water (IP)
1,669
1,502
−10%
Wellton-Mohawk Exchange (P3) 
Water
2,622
2,622
No cut
RWCD Assignment Water (NIA)
627
0
−100%
Hohokam Water (NIA)
4,924
0
−100%
TOTAL CONTRACT ALLOCATION
53,345
41,537
−22%
Mesa retains its M&I, Indian Priority and Wellton-Mohawk 
supplies, but NIA supplies are fully reduced.
Preliminary planning estimate. Headline values are rounded; table total reflects the unrounded calculation.
11

Mesa Has Prepared for Colorado River Drought
Five actions strengthen Mesa’s supply reliability, operational flexibility, and demand management.
1
Invested in renewable 
supplies
Expanded Roosevelt Dam / New Conservation Space to 
support long-term surface-water resilience.
2
Stored water 
underground
Mesa water banking and Arizona Water Bank credits provide 
drought reserve capacity.
3
Established policy tools
Large Water User Ordinance and drought/tiered rates support 
responsible use.
4
Built smart 
infrastructure
AMI water meters and the Central Mesa Reuse Pipeline 
improve efficiency and reuse.
5
Advanced conservation
Turf reductions, xeriscape, and efficient landscape programs 
lower demand.
Mesa Water Resources
12

-
 100,000
 200,000
 300,000
 400,000
 500,000
 600,000
0
20
40
60
80
100
120
140
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
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2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
Population
Avg Daily Water Demand (MGD)
City of Mesa Population & Average Daily Water Usage 1970 to 2025
Average Day Demand
(mgd)
Population
13

Lost & Unaccounted for Water
• Compares the water leaving 
the Treatment Plant vs. what 
is metered to the customer
• National Average is 17%
• AZ State Law Required to 
stay under 10%
• Since AMI project started it 
has dropped below 5%
• Actively doing leak 
detection to find & fix leaks
0.00%
1.00%
2.00%
3.00%
4.00%
5.00%
6.00%
7.00%
8.00%
9.00%
10.00%
December
May
October
March
August
January
June
November
April
September February
July
December
May
2020
2021
2021
2022
2022
2023
2023
2023
2024
2024
2025
2025
2025
2026
% Lost & Unnacounted Water
14

Since 2016, Mesa has saved enough water to fill Saguaro Lake.
 That’s over 70,000 acre-feet of water.
15

16

17
0
20,000
40,000
60,000
80,000
100,000
120,000
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
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2026
2027
2028
2029
2030
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2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
Acre-Feet
Off Project Water Supplies vs Demand Scenarios (No CAP Cuts) 1990-2050
GRIC Exchange M & I Priority Water
Total Indian & NIA Contracts
Subcontract M & I Priority Water
NCS Water post SCIF
ADWR Groundwater Allowance and Incidental Recharge
NCS Water pre SCIF
Long-Term Storage Credits
91st Ave Advanced Water Purification Facility
Bartlett Dam Water
Historical Off-Project Demands
Projected Average Growth Off-Project Demands
Projected Moderate Growth Off-Project Demands

18
0
20,000
40,000
60,000
80,000
100,000
120,000
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
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2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
Acre-Feet
22% Cut to Colorado River Supplies vs Demand Scenarios 1990-2050
GRIC Exchange M & I Priority Water
57% Cut to Total Indian & NIA Contracts
14% Cut to M&I Priority Water
NCS Water post SCIF
Arizona Water Banking Authority
ADWR Groundwater Allowance and Incidental Recharge
NCS Water pre SCIF
Long-Term Storage Credits
91st Ave Advanced Water Purification Facility
Bartlett Dam Water
Historical Off-Project Demands
Projected Average Growth Off-Project Demands
Projected Moderate Growth Off-Project Demands

19
0
20,000
40,000
60,000
80,000
100,000
120,000
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
Acre-Feet
50% Cut to Colorado River Supplies vs Demand Scenarios 1990-2050
GRIC Exchange M & I Priority Water
57% Cut to Total Indian & NIA Contracts
50% Cut to M&I Priority Water
NCS Water post SCIF
Arizona Water Banking Authority
ADWR Groundwater Allowance and Incidental Recharge
NCS Water pre SCIF
Long-Term Storage Credits
91st Ave Advanced Water Purification Facility
Bartlett Dam Water
Historical Off-Project Demands
Projected Average Growth Off-Project Demands
Projected Moderate Growth Off-Project Demands

Actions Mesa Will Take in Response to
Reduced Colorado River Supplies
A staged response: use available reserves, protect customers, and continue building long-term resiliency.
1
NEAR-TERM RESERVE
Utilize the Water 
Bank
Use Arizona Water Bank 
and Mesa bank resources 
to firm reductions when 
available and appropriate.
2
RESERVE SUPPLIES
Utilize NCS Water 
and Groundwater
Activate reserve supplies 
such as New Conservation 
Space water to reduce 
pressure on the operating 
portfolio.
3
NEW SUPPLIES
Investment in Bartlett 
/ Advanced Water 
Purification
Continue regional supply 
development and 
partnership opportunities 
that add flexibility over 
time.
4
OPERATIONAL READINESS
Deploy Drought 
Plans as Needed
Scale actions based on 
conditions, shortage 
severity, customer 
impacts, and Council 
policy direction.
Response principle: preserve reliability, maintain flexibility, and phase actions to match actual shortage conditions.
Mesa Water Resources
20

Additional Actions to Enhance Portfolio Resilience
• Recommend updates to Water 
Shortage Plan
• Recommend updates to Large 
Water User Ordinance
• Real time leak detection through 
Smart metering
• Pursue grants and funding 
opportunities for additional 
conservation investments
21

Regional 
Partnerships and 
Long-Term Solutions
• New Groundwater Wells to recover LTSCs
• Raise Bartlett Dam
• SCIF (connect the canal systems)
• Divert more Reuse Water to the Gila River 
Indian Community
• State Importation Projects led by WIFA
• Advanced Water Purification at 91st Ave 
WWTP – Exchange Water
• Septic to Sewer
• Federal funding to support improvements 
on the Colorado River system and 
development of replacement supplies
22

Key Takeaways
Mesa began building a resilient water portfolio a 
half century ago and must continue to invest in 
new supplies
Additional Supply reductions will be inevitable 
starting in 2027
Uncertainty regarding potential reductions beyond 
2028. 
Water Conservation is a tool that can temper future 
demand
The cost of future supplies will be higher than 
current supplies
23

To learn what Mesa is doing and how residents 
can help, visit mesaaz.gov/watersupply
24