City of Grover Beach
Draft Long-Term Water Supply Study
City Council Presentation
08/24/2026
• Introductions and Study Purpose
• Water Supply and Demand
Assessment
• Water Supply Evaluation Model
Results
Pause for Council Questions
• Supplemental Supply Alternatives
Evaluation
• Funding Opportunities for Most
Viable Alternatives
• Next Steps for Consideration
Closing Council Questions/Public
Comment
Agenda
Introductions
• Long-Term Water Supply Study Technical Team
oDan Heimel, Confluence Engineering Solutions
o Charlotte Arnao, Confluence Engineering Solutions
o Ryan Aston, Confluence Engineering Solutions
o Tom McCarthy, Santiago Water Strategies
• Communications and Community Engagement Team
o Tracy Campbell, CEA Strategies
o Carolyn Berg, Koble Collaborative
• The reality is...
o Our region faces vulnerabilities such as increasing climate variability. o The current water supply strategy will not meet future needs. oThis first-ever water study will assist the City identify and determine the best reliable water supply portfolio for the future. o Evaluating current water sources, future challenges, and supply reliability options will reduce risk and allow the City to adapt to changing conditions for both residents and businesses.
Purpose of Long-Term Water Supply Study
Community Engagement
• Two small group learning sessions
• Online survey
• Two community workshops
• Integrated communications
• Dedicated study webpage
• Email
• Community mailer (postcard)
• City newsletter articles
• Social media
• FAQs
Study Webpage
Water Supply and Demand
Assessment
Lopez Reservoir
800 Acre-Feet per Year (AFY)
Water Supply Portfolio
Santa Maria River Valley
Groundwater Basin
1,407 Acre-Feet per Year (AFY)
Key Vulnerabilities
Possible
Seawater
Intrusion
Source Current Vulnerabilities Future Vulnerabilities
Lopez Reservoir Low Reservoir Response Plan
(LRRP)
Draft Habitat Conservation Plan
(HCP) and Lopez Downstream
Release Plan (LDRP)
Santa Maria River
Valley
Groundwater Basin
Seawater intrusion risk
Tightened sustainable production
constraints to avoid seawater
intrusion
City of Grover Beach Current Water Demand
• Demand declined ~32% since
2010 and remained near that level
("demand hardening")
• City exceeds 2040 State standards
for conservation (~17% below)
• Current 5-year average demand
(2021-2025): ~1,220 AFY, 85 GPCD
Large decreases in
demand over time
attributed to
conservation and
other initiatives.
2012 – 2016
Drought
Large decreases in
demand over time
attributed to
conservation and
other initiatives.
2012 – 2016
Drought
Planned Projects Demand
Large decreases in
demand over time
attributed to
conservation and
other initiatives.
2012 – 2016
Drought
Planned Projects Demand
2020 UWMP Demand
Large decreases in
demand over time
attributed to
conservation and
other initiatives.
2012 – 2016
Drought
Planned Projects Demand
2020 UWMP Demand
5-Year Average Demand
Water Supply Evaluation
Model Results
Water Supply Evaluation Model
• Simulates supply and demand
balance over 30 years
• Historical hydrologic record:
1996 through 2025
• Supply deficits = annual
shortfall between available
supply and projected demand
• Dispatch order: Lopez
Reservoir first, then
groundwater
Model Scenarios
Scenario Demand Basis Lopez Supply Groundwater Supply
Primary
Scenarios
Current
Vulnerabilities
Planned Projects
Demand
800 AFY with LRRP
reductions
Historical average (500
AFY)
Future
Vulnerabilities
Planned Projects
Demand
800 AFY with HCP
LDRP reductions
NCMA modeling
baseline entitlement
(~351 AFY)
Sensitivity
Analysis
Scenarios
Future
Vulnerabilities &
High Demand
2020 UWMP
Demand
800 AFY with HCP
LDRP reductions
NCMA modeling
baseline entitlement
(~351 AFY)
Future
Vulnerabilities &
No Growth
5-Year Average
Demand
800 AFY with HCP
LDRP reductions
NCMA modeling
baseline entitlement
(~351 AFY)
10% Lopez
Reservoir allocation
reductions under
the LRRP
10% Lopez
Reservoir allocation
reductions under
the LRRP
Historical average
groundwater
production (500
AFY)
10% Lopez
Reservoir allocation
reductions under
the LRRP
Historical average
groundwater
production (500
AFY)
Deficits range from
15 to 241 AFY and
end at 164 AFY in
Year 30
Lopez Reservoir
allocation reductions
under the HCP LDRP
due to lower amount
of water in storage
Regional
Groundwater
Modeling Production
Restriction (351 AFY)
Deficits range from
143 to 471 AFY and
end at 313 AFY in
Year 30
Lopez Reservoir
allocation reductions
under the HCP LDRP
due to lower amount
of water in storage
Regional
Groundwater
Modeling Production
Restriction (351 AFY)
Deficits range from
242 to 745 AFY and
end at 586 AFY in
Year 30
2020 UWMP Demand
assumed higher percapita water use (117
GPCD) than recent
historical trends (85
GPCD)
Lopez Reservoir
allocation reductions
under the HCP LDRP
due to lower amount
of water in storage
Regional
Groundwater
Modeling Production
Restriction (351 AFY)
Deficits range from
69 to 229 AFY and
end at 69 AFY in Year
30 5-year average
demand (1,220 AFY)
Estimated Supply Deficits Across Scenarios (AFY)
Current
Vulnerabilities
Scenario
Future
Vulnerabilities
Scenario
Future
Vulnerabilities &
High Demand
Scenario
Future
Vulnerabilities &
No Growth
Scenario
Year 5 Deficit 55 204 313 69
Year 10 Deficit 122 271 399 69
Year 20 Deficit 149 298 572 69
Year 30 Deficit 164 313 586 69
Maximum Deficit 241 (Year 27) 471 (Year 28) 745 (Year 28) 229 (Year 27) • Supply deficits are real and not dependent on worst-case assumptions
• The No Growth scenario confirms supply challenge is
NOT driven by growth alone
• Minimum supplemental supply of ~241 AFY is a
reasonable target for City based on max deficit in Current Vulnerabilities scenario
Key Model Conclusions
Questions?
Supplemental Supply
Alternatives Evaluation
• Conservation
• Desalination
• Local/Regional Water Purchase
• Purchase of State Water Project (SWP) Contract
• Recycled Water - Direct Potable Reuse (DPR)
• Recycled Water - Indirect Potable Reuse (IPR)
• Recycled Water - Non-Potable Recycled Water
• Stormwater Capture
Eight Alternatives Evaluated
Evaluation Criteria
Reliability
Consistency of supply delivery under normal
and drought conditions
Resiliency
Ability to perform during drought,
emergencies, or other disruptions
Life-Cycle Cost
Upfront, ongoing, and total cost of ownership
Quantity of Supply
Volume of new water the source can
realistically provide (min 241 AFY threshold)
General Feasibility
Technical and regulatory feasibility
Timing
How quickly water could be delivered (2 to
15+ years depending on alternative)
Environmental Impacts
Impacts to local ecosystems, carbon
footprint, water quality
Environmental Justice
Fair distribution of costs, benefits, and
burdens across the community
Quantity of Supply Threshold Analysis
Alternatives assessed against a minimum supply quantity threshold of 241 AFY (max deficit in Current Vulnerabilities scenario).
Alternatives that cannot realistically meet this threshold were not advanced as viable alternatives.
Alternative Expected Supply (AFY) Meets 241 AFY Threshold? Local/Regional Water Purchase 300 to 499 Yes ✓
Purchase of SWP Contract 500 to 999 Yes ✓
IPR Recycled Water 300 to 499 Yes ✓
DPR Recycled Water 300 to 499 Yes (ranked lower — cost and timeline) Desalination >= 1,000 Yes (ranked lower — cost and timeline) ▼ Alternatives below do NOT meet the 241 AFY minimum threshold ▼ Conservation (will continue as a foundational practice in the City) < 100 No ✗ Non-Potable Recycled Water < 100 No ✗
Stormwater Capture < 100 No ✗
Supplemental Water Supply Alternatives Evaluation Scoring
1. Local/Regional
Water Purchase
• Purchase water rights from
neighboring agency or
agricultural user
• Flexible and fast to
implement (~3 year
timeline)
• Reliability depends on
source and contract terms
• 300-499 AFY expected yield
2. Purchase of State Water Project
(SWP) Contract
• Access SWP water through
SLOCFCWCD and existing
Zone 3 infrastructure
• Variable year-to-year
delivery (5%-100% of
entitlement)
• Drought Buffer allocation
builds storage for lowallocation years
• 3 to 7 year timeline
• 500-999 AFY expected yield
3. Indirect Potable Reuse (IPR)
Recycled Water
• Advanced wastewater
treatment for groundwater
recharge
• Highly resilient; tracks
wastewater generation, not
hydrology
• Significant infrastructure
investment
• 7 to 10 year timeline
• 300-499 AFY expected yield
Three Most Viable Alternatives
Local/Regional Water Purchase Supply
Evaluation Modeling
CURRENT VULNERABILITIES FUTURE VULNERABILITIES
• Supplemental supply of 200 AFY eliminates deficits over 30-year planning horizon
• Stored Lopez averages 236 AFY
• Supplemental supply of 350 AFY eliminates deficits over 30-year planning horizon
• Stored Lopez averages 215 AFY
Purchase of SWP Contract Supply
Evaluation Modeling
CURRENT VULNERABILITIES FUTURE VULNERABILITIES
-
200
400
600
800
1,000
1,200
1,400
1,600
Acre-Feet
Stored SWP Water Stored Lopez Water Groundwater Utilized SWP Water Utilized Stored SWP Utilized Lopez Water Utilized Stored Lopez Water Utlized Planned Projects Demand • Supplemental supply of 400 AFY (200 AFY Water Service Amount + 200 AFY Drought Buffer) eliminates deficits over 30-year planning horizon
• Stored Lopez averages 260 AFY, Stored SWP averages 30 AFY • Supplemental supply of 700 AFY (350 AFY Water Service Amount + 350 AFY Drought Buffer) eliminates deficits over 30-year planning horizon
• Stored Lopez averages 405 AFY, Stored SWP averages 50 AFY IPR Recycled Water Supply
Evaluation Modeling
CURRENT VULNERABILITIES FUTURE VULNERABILITIES
• Supplemental supply of 200 AFY eliminates deficits over 30-year planning horizon
• Stored Lopez averages 236 AFY
• Supplemental supply of 350 AFY eliminates deficits over 30-year planning horizon
• Stored Lopez averages 215 AFY
Supplemental Supply Quantity Ranges
Alternative Current Vulnerabilities
(Minimum)
Future Vulnerabilities
(Maximum)
Local/Regional Water
Purchase 200 AFY (firm) 350 AFY (firm)
Purchase of SWP Contract
400 AFY Table A (200
AFY Water Service
Amount + 200 AFY
Drought Buffer)
700 AFY Table A (350 AFY
Water Service Amount + 350
AFY Drought Buffer)
IPR Recycled Water 200 AFY (firm) 350 AFY (firm)
Funding Opportunities for
Most Viable Alternatives
Water Supply Project Funding:
Three Distinct Cost Types
1. Capital cost (infrastructure)
2. Contractual cost (securing water rights/entitlements)
3. Water/commodity cost (ongoing water purchase)
This distinction drives funding eligibility:
Grants and loans generally apply only to capital cost. Development impact fees can potentially support both capital and contractual cost, but likely not ongoing water/commodity cost. City funding/Prop 218 rates are best suited to fund water/commodity cost.
Summary of Funding Opportunities
Alternative Currently Available Funding Potentially Available Funding
5.1 SWP Contract
• City funds
• Prop 218 rate adjustment
• State/federal grant and loan programs
(likely limited to capital components).
• Development impact fee (limited to
capital and contractual costs; excludes
water purchase).
5.2 Local/Regional
Water Purchase
• City funds
• Prop 218 rate adjustment
• State/federal grant and loan programs
(likely limited to capital components).
• Development impact fee (unlikely -
excludes water purchase).
5.3 IPR Recycled
Water
• State/federal grant and loan
programs supported by city
funds and Prop 218 rate
adjustment
• State/federal grant and loan programs
with pending guidelines/solicitations.
• Development impact fee (limited to
growth-related capacity).
Grant & Loan Funding by Alternative (1)
SWP Contract (5.1) and Local/Regional Purchase (5.2)
• Grant and loan funding likely applies only to capital infrastructure needs related to Alternatives 5.1 and 5.2, e.g., Lopez Pipeline turnout, pipeline/pump station upgrades.
• Potentially available:
• Drinking Water State Revolving Fund (DWSRF)
• Infrastructure State Revolving Fund (ISRF)
• Proposition 4 regional conveyance funding
Grant & Loan Funding by Alternative (2)
IPR Recycled Water (5.3)
• Currently available:
• Water Recycling Funding Program (WRFP)
• Clean Water State Revolving Fund (CWSRF)
• WaterSMART Title XVI Water Reclamation and Reuse Program • Water Infrastructure Finance and Innovation Act (WIFIA) • Potentially available:
• Integrated Regional Water Management (IRWM)/Watershed Resilience Program • Proposition 4 water recycling allocation
• Proposition 4 regional conveyance funding
Development Impact Fees Across Alternatives
• Governed by the Mitigation Fee Act (Gov. Code § 66000 et seq.) • Fees may only fund the incremental capacity or facilities attributable to new development – not existing deficiencies.
• Fee amount must be roughly proportional to the burden new development creates. • A nexus study is used to establish and document this proportionality. • Fees then adopted by ordinance or resolution.
For 5.1: may cover facility/entitlement acquisition costs – excludes ongoing water purchase.
For 5.2: unlikely due to exclusion of water purchase as eligible cost. For 5.3: limited to the share of facility capacity attributable to growth.
Next Steps
Next Steps for Consideration
• Advance feasibility & planning for preferred supplemental supplies • Explore local & regional water purchase opportunities • Engage SLOCFCWCD regarding SWP Subcontract Opportunities • Engage SSLOCSD regarding IPR treatment feasibility & cost-sharing • Pursue grant & loan funding for preferred alternative(s) • Monitor HCP process and adjust supply planning accordingly • Continue community engagement as City advances toward decision The Time to Plan Is Now
Approximate time from planning to first water delivery:
Local/Regional
Water Purchase
~3 years
Purchase of
SWP Contract
3-7 years
IPR Recycled
Water
7-10 years
Pursuing near-term planning steps for the City's preferred water supply alternative(s) will help build a resilient and reliable water supply portfolio that supports Grover Beach's long-term growth, economic vitality, and quality of life.
Questions?
Thank you for your
participation!
For additional information, please visit the
Project Website:
Pocket Slides
Lopez Reservoir: Key Vulnerabilities
Current Vulnerabilities: Low Reservoir
Response Plan (LRRP)
• Enacted when storage drops below
20,000 AF and County declares a
drought emergency (10% reductions in
2016 and 2022)
Future Vulnerabilities: Draft Habitat
Conservation Plan (HCP) and Lopez
Downstream Release Plan (LDRP)
• Aims to increase Arroyo Grande Creek
flows for steelhead trout through
mandatory downstream releases
Santa Maria River Valley Groundwater Basin: Key Vulnerabilities Current Vulnerabilities: Seawater intrusion risk
• Monitored through the Deep Well Index (DWI)
• 2008-2009, chloride spike from ~50 to ~700 mg/L
• NCMA agencies reduced pumping significantly, preventing recurrence, but risk remains
Future Vulnerabilities: Tightened sustainable production constraints to avoid seawater intrusion under future conditions • City’s current sustainable production up to ~500 AFY could tighten to ~351 AFY, according to Regional hydrogeologic modeling
The Time to Plan Is Now
Approximate time from planning to first water delivery:
Local/Regional
Water Purchase
~3 years
Purchase of
SWP Contract
3-7 years
IPR Recycled
Water
7-10 years
Pursuing near-term planning steps for the City's preferred water supply alternative(s) will help build a resilient and reliable water supply portfolio that supports Grover Beach's long-term growth, economic vitality, and quality of life.
Community Engagement Plan
• Multi-faceted plan to inform and engage the community. • Plan emphasized early listening, transparent communication, independent technical expertise, and public participation.
• Meaningful input from residents, businesses, development community, and community leaders.
• Build transparency and community trust in support of the technical analysis. • Timeline: March – June 2026.
30-Year Demand Projections for the Study
• Primary demand basis for Study:
Planned Projects Demand (85 GPCD
assumption)
• Sensitivity analysis scenarios also
evaluated:
• 2020 UWMP demand (117 GPCD):
ranges from ~1,393 to 1,737 AFY
(upper-bound condition)
• No-growth scenario: flat 1,220 AFY
throughout (lower-bound condition)
• San Luis Obispo Council of Governments
(SLOCOG) 2060 Regional Growth
Forecast population projections were
used to develop planned projects
demand for 2041–2055 and UWMP
demand for 2046–2055.
0 500
1,000
1,500
2,000
Demand (Acre -Feet)
Projected Demands for City of Grover Beach Water Supply Evaluation Modeling
5-Year Average (2021-2025) Planned Projects 2020 Urban Water Management Plan (UWMP) Primary Demand Assumption
Supplemental Supply Modeling Methodology
Each alternative was tested at increasing supply volumes until deficits were eliminated in all 30 years, establishing a supplemental supply range from Current to Future Vulnerabilities conditions.
Supply Dispatch Order
1. Groundwater
• Used first each year up to the
sustainable limit
2. Supplemental supply
• New supply used before
Lopez, preserving Lopez for
storage
3. Lopez Reservoir
• Unused Lopez allocation
banks into reservoir storage as
a drought buffer
Stored Lopez Water Local/Regional Water Purchase Supplemental Supply Understanding the SWP Contract Structure
Think of it like a bank account with two buckets:
Water Service Amount (WSA)
(200 AFY)
Your checking account
Water you can actually “spend”
that’s delivered directly to your
system each year, up to this
amount.
+
Drought Buffer
(200 AFY)
Your savings account
Cannot be delivered directly, but
any unused Table A allocation
(including this buffer)
automatically rolls into SWP
storage for use in future dry
years.
=
Table A Entitlement
(400 AFY total)
Your total credit line
The full amount available
each year but only the WSA
portion can be used directly.
Why is the Drought Buffer equal to the WSA?
Most SLOCFCWCD SWP subcontractors hold a Drought
Buffer equal to their Water Service Amount . This is the standard contract structure established under the
SLOCFCWCD's subcontracting program.
Why does storage matter? In low-allocation
drought years, SWP may deliver as little as 5% of
entitlement. Accumulated Drought Buffer storage fills
the gap, turning a volatile supply into a reliable one.