2025 San Bernardino Valley
Regional Urban Water
Management Plan
EXECUTIVE SUMMARY
1 Executive Summary
2025 San Bernardino Valley Regional Urban Water Management Plan Due to the dedicated and collaborative efforts of the regional water managers, water resources in the San Bernardino Valley continue to support thriving communities and are vital to protect and enhance natural resources. Water supply reliability over the next 25 years continues to remain strong and will be able to withstand uncertainties, including extended drought conditions.
The 2025 Regional Urban Water Management Plan (RUWMP or Plan) was prepared as a collaborative effort by nine Participating Agencies: San Bernardino Valley Municipal Water District, City of Colton, City of Loma Linda, City of Redlands, City of Rialto, City of San Bernardino Municipal Water Department, Riverside Highland Water Company, South Mesa Water Company, and West Valley Water District.
2 Purpose of the Plan
The California Water Code requires urban water suppliers within the state to prepare and adopt Urban Water Management Plans (UWMPs) for submission to the California Department of Water Resources (DWR) every 5 years. A UWMP describes water supply planning for a 25-year planning period in five-year increments and identifies water supplies needed to meet existing and future demands. The demand analysis identifies supply reliability under three hydrologic or rainfall conditions: an average (or normal) year, a single-dry year, and multiple-dry years.
A UWMP is intended to function as a planning tool to guide broad-perspective decision making by water supply managers. It is a long-term, general planning document, rather than an exact blueprint for supply and demand management. Water management in California is not a matter of certainty, and planning projections may change in response to a number of factors. The long term perspective provided by a UWMP supports decisions by water managers to invest in feasible and cost-effective options and opportunities to maintain water supply reliability into the future.
This UWMP addresses several planning objectives, including:
1. Identification of the potential sources of water supply and the reasonable amount of supply available from each source.
2. Estimation of probable water demand based on a reasonable set of assumptions regarding growth and the implementation of good water management practices.
3. Evaluation of how current and future water supply and demand compare, based on the supplies anticipated to be pursued.
3 Regional Collaboration
Beginning with the 2010 UWMP cycle, San Bernardino Valley Municipal Water District (San Bernardino Valley), the region’s wholesale water supplier, and several retail water agencies in the region have collaborated to prepare a San Bernardino Valley Regional UWMP (RUWMP) that addresses the entire San Bernardino Valley service area (Region).
The purpose of jointly preparing the RUWMP is to facilitate a consistent evaluation of water sources common to the various agencies, to take advantage of group knowledge and experience, and to reduce collective preparation costs. The unique document structure of the RUWMP preserves each agency’s ability to independently convey unique water management considerations for their service area while leveraging the regional information and activities that are applicable to all.
In addition to the Participating Agencies, this RUWMP incorporates data from other agencies within the San Bernardino Valley that rely wholly or partially on the shared water resources analyzed in this Plan. While these agencies are not signatories to this RUWMP, their water demands and associated supply needs are included to accurately evaluate regional water supply reliability through 2050.
Key Takeaways
• Coordinated regional planning: Since 2010, San Bernardino Valley and regional retailers have jointly prepared a Regional UWMP to consistently evaluate shared water resources and reduce planning costs. • Local flexibility with regional consistency: The RUWMP structure supports agency‑specific planning while relying on common regional analyses and data.
• Complete view of shared water demands: The Plan includes demands from both participating and non‑signatory agencies to accurately assess regional water supply reliability through 2050.
4 Service Area
San Bernardino Valley and eight retail water agencies collaborated to produce this 2025 RUWMP spanning the San Bernardino Valley service area.
The Region encompasses more than 350 square miles and includes a vast metropolitan area that is home to approximately 725,000 residents and a robust and diverse economy.
RIALTO
RIVERSIDE
SAN
BERNARDINO
YUCAIPA
REDLANDS
Santa Ana
River
Seven Oaks
Dam
Seven Oaks
Dam
15 60
10 215
210
Riverside
Narrows
Riverside
Narrows
COLTON
LOMA
LINDA
Recharge Basins
San Bernardino Valley Service Area
Upper Santa Ana River Watershed
0 1 2 4
Miles
0 10,000 20,000
Feet
N
5 Organization of the Plan
The organization of the 2025 RUWMP is depicted below.
Each Participating Agency adopted the Regional Context and Supporting Information, Parts 1 and 3, and their respective chapters and appendices of Parts 2 and 4.
Regional Context
Part 1 contains the
information needed to
meet a portion of the
UWMP Act requirements
for the local agencies
who are using this Plan to
meet their 2025 UWMP
Requirements.
1. Introduction
2. Region Description
3. Regional Water
Sources and
Management
4. Regional Water Use
5. Comparison of
Regional
Supplies and Demands
CONTENTS
2025 San Bernardino Valley
Regional Urban Water Management Plan
Part I: Regional Context
Local Agency
UWMPs
Part 2 provides
supplemental
information for the
nine local agencies who
are using this Plan to
meet their 2025 UWMP
requirements.
1. San Bernardino
Valley
Municipal Water
District
2. City of Colton
3. City of Loma Linda
4. City of Redlands
5. City of Rialto
6. Riverside Highland
Water Company
7. San Bernardino
Municipal Water
Department
8. South Mesa Water
Company
9. West Valley Water
District
2025 Urban Water
Management Plan
Public Draft
Part 2 Chapter 9
APRIL 2026 WEST VALLEY WATER DISTRICT
Regional Supporting
Information
Part 3 includes all
of the supporting
documentation
referenced in Part 1
that is applicable to the
region as well as the
regulatory compliance
guide that DWR will
use to verify that Part 1
meets requirements.
2020 IRUWMP EXECUTIVE SUMMARY 3
PART 3: REGIONAL
SUPPORTING INFORMATION2025
Photo Credit: San Bernardino Valley Water Conservation District
SAN BERNARDINO VALLEY
REGIONAL URBAN
WATER MANAGEMENT PLAN
UWMP Agency
Supporting
Information
Part 4 includes a set of
supporting documentation
for each Participating
Agency corresponding to
their respective chapters
in Part 2. Documents will
include the regulatory
compliance guide that
DWR will use to verify the
agency has met the UWMP
Act requirements, the
agency’s Water Shortage
Contingency Plan and
other documents specific
to each agency.
2020 IRUWMP EXECUTIVE SUMMARY 4
PART 4: UWMP AGENCY
SUPPORTING INFORMATION
SAN BERNARDINO VALLEY
2025
REGIONAL URBAN
WATER MANAGEMENT PLAN
Photo Credit: San Bernardino Valley Water Conservation District
CONTENTS
6 Outreach and Engagement
Management of water resources in the Region takes place within a complex legal and institutional framework. Development of this RUWMP involved the cooperation of many parties engaged in regional water management as well as the public.
In accordance with the UWMP Act, the Participating Agencies issued a Notice of Plan Preparation to cities and counties, as well as other entities in the region, engaged in water management on March 3, 2026, more than 60 days prior to the public hearings. This notice informed stakeholders that the 2025 RUWMP was being prepared and invited input.
The Participating Agencies encouraged public participation in the preparation of this Plan to incorporate public feedback on water management and reliability in the Region. Public comments on the draft RUWMP were invited via email announcements, website postings and newspaper notices, and during the public hearing prior to each Participating Agency adopting the RUWMP.
In addition, two workshops with the
Participating Agencies were conducted to
align the approach for RUWMP preparation
and to review the results of the regional
water supply and demand analysis. Direct
engagement with non-participating agencies
who rely wholly or partially on the shared
water resources was conducted to share
information and promote consistency with
individual retail agency UWMPs that are not
part of this RUWMP.
Key Takeaways
• Developed with regional partners
and public input.
• Notice of Plan Preparation sent
more than 60 days before hearings.
• Comments gathered via email, web,
newspaper, and public hearings.
• Two workshops aligned approach and
reviewed supply/demand results.
7 Regional Growth
The Region has experienced rapid growth in the past, adding approximately 8,000 people each year from 1990 to 2010. Growth slowed from 2010 to 2020 and is projected to continue at a more moderate rate than previously projected, according to the recent growth forecast developed by Southern California Association of Governments (SCAG) for the 2024 Connect SoCal Regional Transportation Plan (2024 RTP).
SCAG’s 2024 population growth projections have declined from the last Connect SoCal RTP in 2020 due to ongoing economic impacts of COVID-19, pandemic-related death increases, increasingly negative net domestic migration, decline in births, and near-zero level of foreign immigration. SCAG’s 2024 update uses a 2019 base year and incorporates a broader data range from 2016 to 2022, capturing key post-COVID shifts in population, employment, and household trends.
Figure ES-1: Population Projection for the San Bernardino Valley Service Area 8 While the 2024 SCAG RTP projects
slower growth, the population
within the San Bernardino Valley
service area is expected to grow
by about 140,000 by 2050 from a
2020 Census value of 709,858. By
2050, the San Bernardino Valley
service area is expected to have
a population of approximately
847,000 people.
Key Takeaways
• The Region grew rapidly from 1990 to 2010,
then slowed from 2010 to 2020. Future
growth is projected to remain moderate.
• SCAG’s 2024 projections are lower than the
2020 RTP, reflecting post‑COVID shifts
• Despite slower growth, the service area
population is still projected to rise by
approximatley 140,000 by 2050.
9 Figure ES-2: Regional Demand Projections for Regional Supplies in the RUWMP Regional Demand
As a result of slower projected population growth, and continued gains in water use efficiency, the total demand projections in this RUWMP are also slightly lower than the projections from 2020, totaling approximately 208,000 acre-feet per year (AFY) by 2050, including demands for potable water, recycled water and non-potable groundwater.
These totals include demands from all entities within the San Bernardino Valley that rely wholly or partially on the shared water resources analyzed in this RUWMP. For agencies who rely only partially on supplies evaluated in the Plan, the demand projection only includes their use of Regional supplies analyzed in this Plan to ensure a consistent comparison of supplies and demands.
10 Figure ES-3: San Bernardino Basin Precipitation Index Regional Climate
Climate in the Region is characterized by
relatively hot, dry summers and cool winters
with intermittent precipitation. The historical
record indicates that periods of below-average
precipitation can last more than 30 years, such
as the dry period that extended from 1939 to
1969. The Region has been experiencing an
ongoing drought since 1999, indicated by a
long term downward trend in the Precipitation
Index, except for a few wet years.
11 Regional Water Sources
The Region’s diverse water supplies support the regional economy, environment and quality of life.
Securing a reliable water supply is the primary mission of San Bernardino Valley and the Participating Agencies. The Region relies on a diversified portfolio of water supplies to meet the needs of its residential, commercial, and institutional customers. The Region’s water supply portfolio consists of imported water, local groundwater, local surface water and recycled water.
CHINO
RIVERSIDE-
ARLINGTON
RIVERSIDE-
ARLINGTON
RIALTO-
COLTON
SAN
BERNARDINO
YUCAIPA
SAN
TIMOTEO
SAN
TIMOTEO
Santa Ana
River
Seven Oaks
Dam
Seven Oaks
Dam
15 60
10 215
210
Riverside
Narrows
Sterling Natural
Resource Center
Riverside
Narrows
Sterling Natural
Resource Center
Water Treatment Plant
Wastewater Treatment Plant
Recharge Basins
Groundwater Basins
San Bernardino Valley Service Area
Upper Santa Ana River Watershed
0 1 2 4
Miles
0 10,000 20,000
Feet
N
12 Imported Water
San Bernardino Valley’s imported water comes
from the State Water Project (SWP). San Bernardino
Valley is the fifth largest State Water Contractor,
with a maximum annual entitlement of 102,600
acre foot (AF). However, the amount of SWP water
delivered in a given year depends on a number
of factors, including the demand for the supply,
amount of rainfall, snowpack, runoff, water in
storage, pumping capacity from the Delta, and
legal/regulatory constraints on SWP operation.
Regulatory and environmental constraints have
changed over time, becoming more restrictive and
impacting SWP availability. According to modeling projections provided in the DWR 2025 SWP Delivery Capability Report (DCR), future long-term average SWP deliveries are expected to be 54% of total allocations under current conditions and 46% under 2043 conditions, when accounting for the impacts of climate change. During very dry years, allocations have been as low as 5%, which occurred in 2014, 2021 and 2022. During a 5-year drought, allocations are expected to average 15% over that period.
However, during wet years, a much larger portion of the allocation is available; this Plan is based on 83% for a wet year, but in 2023, SWP allocations reached the full 100%.
Due to the broad range of SWP supply availability in different year types, storage is a fundamental component of regional water management that enables the Region to maximize beneficial use of SWP supplies when they are available and store them for use in future droughts. Local groundwater basins have over 10 million AF of total storage capacity to support optimization of SWP supplies.
Sites Reservoir
The Sites Reservoir Project
is a proposed 1.5 million
AF water storage project in
northern California that would
capture extra water from the
Sacramento River and store it
in a large off stream reservoir
for use during dry years. San
Bernardino Valley is one of the
proponents of Sites Reservoir
and would receive a share of
the water during average and
drier years, with a long term
average of 11,200 AFY.
13 Local Surface Water
Local surface water is diverted from
the Santa Ana River and two of its
tributaries — Mill Creek and Lytle Creek
— and either treated for potable use,
delivered as non-potable irrigation
water, or routed into spreading basins
for groundwater recharge.
Surface water flows can be highly
variable from year to year. When
surface water flows are low, retail
agencies shift their supply strategy to
use groundwater and/or SWP water
instead of local surface water. During
wet periods when local surface water
flows are high, retail agencies typically
prioritize this supply, and excess flows
are captured for recharge to maximize
local storage for use in future dry years.
Enhanced Recharge
In 2025, San Bernardino Valley,
in partnership with Western
Municipal Water District,
Riverside Public Utilities, and
San Bernardino Valley Water
Conservation District, proudly
marked the completion of the
Santa Ana River Enhanced
Recharge Phase 1B Project, which
will allow up to 80,000 AF of local
stormwater per year during wet
years to be captured and stored
in the local aquifer, creating a
critical supply of groundwater for
future drought years.
14 Groundwater
Local groundwater provides about
80% of the supply for Participating
Agencies in an average year. All of the
Region’s groundwater is produced from
four distinct groundwater basins: San
Bernardino, Rialto-Colton, Riverside-
Arlington, and Yucaipa. Together, these
four basins provide over 140,000 AFY
of annual supply and a total of 10
million AF of local storage capacity. The
Region's primary drought resilience
strategy is to recharge water into these
basins when it is available to provide
stored water for use in dry years.
Key Takeaways
• The Region has a diverse portfolio of
imported water, groundwater, local
surface water, and recycled water.
• Groundwater provides
approximately 80% of the Region's
supply in an average year and 10
million AF of local groundwater
storage capacity provides a critical
resource for drought resilience.
• Local surface water and imported
water supplies are highly variable
but can be captured and recharged,
along with recycled water, to
increase local groundwater storage
for use during dry years.
15 15
Recycled Water
The development and use of recycled
water is another important water
supply strategy for the Region.
Recycled water supply is highly reliable
because wastewater flows to treatment
plants remain relatively constant
during dry hydrologic conditions. For
this reason, recycled water is often
considered a drought-proof supply.
Some of the retail agencies in the
Region provide recycled water to their
customers for non-potable uses, such
as irrigation and industrial cooling
water. The Region also recently began
recharging recycled water into the
San Bernardino Basin to increase
groundwater storage. The agencies
in the Region plan to expand recycled
water use in the future, both for
non-potable uses and groundwater
recharge, to increase long- term
regional water supply reliability and
drought resilience.
Regional Recycled Water System
In 2024, the first phase of the
Regional Recycled Water System
was completed when highly
treated water from East Valley
Water District’s Sterling Natural
Resource Center began recharging
the San Bernardino Basin at the
newly constructed Weaver Basins
to store local water for future use.
16 Water Supply Reliability
Every urban water supplier is required to assess the reliability of its water service under normal year, single‑dry year, and multiple‑ dry year hydrologic conditions. Multiple factors can impact supply reliability, including legal, environmental, water quality, and climatic factors. These factors can result in immediate, near‑term, or long‑term impacts to reliability and must be considered in future planning.
The Region’s ongoing efforts to maximize capture of supplies in wet years for later use in dry years is the most important step toward improving the long term reliability of supplies. In addition to the core supplies included in the supply reliability analysis, the Region continues to invest in additional supply and storage projects to improve long term resilience and supply reliability,
including ongoing and expanded recharge
of recycled water, imported water, and
local stormwater. By 2050, these collective
investments in recharge are projected to
contribute over 59,000 AF of additional
groundwater storage each year, on average.
Key Takeaways
• Reliability is assessed for normal,
single‑dry, and multiple‑dry (5‑dry)
years.
• The Region improves reliability by
storing water in wet years through
groundwater recharge.
• The Region projects sufficient
supplies under normal, single‑dry,
and 5‑dry conditions, with no
anticipated shortages over the next
25 years.
17 17
Imported Water Reliability
Of the supplies in the San Bernardino Valley service area, imported water has the highest sensitivity to hydrologic conditions and is subject to reduced availability due to drought, environmental factors, and climate change. These projected supply impacts are included in this analysis and have the potential to limit the amount of water available for groundwater recharge over time, with the impacts being essentially the same in single dry and 5-dry year periods. However, the implementation of the planned Sites Reservoir, which is incorporated into this analysis beginning in 2040, would significantly increase dry year imported water supplies to offset the impacts of SWP reductions.
Local Water Reliability
Groundwater in the local basins can be considered drought resistant, as long as sufficient water is stored during wet periods for use during dry periods, which is the Region’s core water management strategy. Although local surface water is reduced during drought, it is included in the safe yield of the San Bernardino Basin, so it is not evaluated separately in this analysis.
Recycled water is similarly drought resistant, and available recycled water supplies exceed planned uses. Therefore, groundwater and recycled water are assumed to have the same yield in normal year, single-dry year, and multiple-dry year drought scenarios.
Long Term Supply Reliability
As shown in Figure ES-4 (Normal Year Supply and Demand Balance) and Figure ES-5 (Single Dry and 5-Dry Year Supply and Demand Balance) on the next page, the Region projects to have sufficient supplies to meet demands under normal year supply and demand conditions as well as single-dry year and 5-dry year conditions, with a surplus in all years types. 18 Due to long standing and ongoing collaborative efforts of the regional water managers, water resources in the San Bernardino Valley continue to be reliable, with no anticipated shortages in the next 25 years, including during extended drought conditions.
Figure ES-5: Single Dry and 5-Dry Year Supply and Demand Balance (AFY) Figure ES-4: Normal Year Supply and Demand Balance (AFY) 19 Water Efficiency and
Conservation
The Region has invested in expanding and optimizing local water resources to improve enhance long term water supply reliability for its residents. At the same time, the Region continues to advance water use efficiency and conservation programs that have meaningfully reduced per-capita demand and strengthened long-term supply reliability.
These conservation efforts are a core component of the Region’s resource management strategy and help maximize the value of available supplies.
Since 2005, there have been several regulatory changes related to conservation, including new standards for plumbing fixtures, a new landscape ordinance, a state universal retrofit ordinance, metering and billing requirements, new green building standards, demand reduction goals and permanent State-mandated restrictions that were implemented in response to the most recent statewide drought.
Each of the eight participating retail agencies maintain conservation programs to reduce water waste and manage customer demand and San Bernardino Valley provides support at a regional level. These proactive conservation programs, in conjunction with passive conservation due to changes in codes and ordinances, have resulted in significant reductions in retail water use within the Region.
20 The Water Conservation Act of 2009 (SB X7-
7) required a 20% reduction in urban per
capita water use in California by December
31, 2020 (20 by 2020). The bill required
each urban retail water supplier to determine
their baseline per capita water use (gallons
per capita per day or gpcd), develop an urban
water use target for year 2020 and set a 2015
interim urban water use target. Each of the
agencies participating in this Plan met their
2020 targets, and some have continued to
reduce their per capita water demand beyond
the 2020 target. These reductions in per capita water use essentially expand the water supply for the Region by reducing use of regional supplies to meet existing demands.
Going forward, retail suppliers continue to improve water use efficiency and align with the State’s urban water use management strategy (Making Conservation a California Way of Life), the result of two 2018 policy bills enacted by the California Legislature (SB 606 and AB 1668).
Figure ES-6: SB X7-7 Compliance and Water Use Efficiency Improvements Key Takeaways
• The Region’s conservation programs
have reduced per‑capita demand
and strengthened long‑term supply
reliability
• Under SB X7‑7, agencies exceeded
the required 20% per‑capita
reduction by 2020, and the Region
continues to align with “Making
Conservation a California Way of
Life” requirements.
21 Water Shortage
Contingency Plan
The Water Shortage Contingency Plan (WSCP) is a strategic plan that the participating agencies use to prepare for and respond to foreseeable and unforeseeable water shortages.
Although the Plan demonstrates the Region’s strong long term supply reliability, agencies must still plan for potential short term shortages. A shortage may occur due to several reasons, such as water supply quality changes, climate change, drought, regional power outage, and catastrophic events (e.g., earthquake). Additionally, the State may declare a statewide drought emergency and mandate that water suppliers reduce demands, as occurred in 2014 and 2022. Each agency’s WSCP serves as an operating manual that it will use to prevent catastrophic service disruptions through proactive, rather than reactive, mitigation of water shortages. Each WSCP provides a process for an annual water supply and demand assessment and structured steps designed to respond to actual conditions.
Although the water agencies in the Region do not foresee implementing water shortage levels under normal conditions, this level of detailed planning and preparation provide accountability and predictability and help the Region’s water agencies maintain reliable supplies and reduce the impacts of any supply shortages and/or interruptions. 22 23