Integrated Resource Plan

Diamond Valley lake

The Integrated Water Resources Plan

Planning is a hallmark of Metropolitan. It's what makes us successful in delivering water reliability to a region with limited local resources. Since 1996, we've looked 25 years ahead to assess the needs of Southern California and adapt to ever-evolving challenges. The Integrated Water Resources Plan, updated about every five years, is an indispensable tool that guides our water supply investments, programs and policies. It allows our member agencies to make their plans for water deliveries in their service areas. The result - Southern California water supplies are reliable and Metropolitan is braced for change.

Threats to our water supply remain. Uncertainties with how climate change, natural disasters, and regulatory requirements, along with Southern California's population and economy, will impact the region's water supply and demands, require us to continue to adapt and plan to secure our future. Preparing for the uncertainties ahead is critical.

That's why in 2020 we initiated a new IRP process with a fresh approach, looking at multiple scenarios that could play out in the future and how Metropolitan could respond to maintain water reliability for the region.

Our IRP planning does not take place in a vacuum. It is coordinated consistent with other long-term plans such as the new Climate Action Plan and Metropolitan's 2020 Urban Water Management Plan. Metropolitan's IRP is also coordinated with member agency plans to develop local resources.

Contact us for more information about the 2020 IRP planning process.

The 2020 IRP

A New Way to Prepare

The IRP anticipates how much water Southern California can expect from its imported and local supplies, and forecasts regional water demands. Understanding the gap between supplies and demand helps set the targets to maintain reliability and inform the board on what actions Metropolitan and its member agencies can take to close that gap.

But past plans looked at a single forecast. Given all the uncertainties we face, the 2020 IRP looks at multiple scenarios that could plausibly unfold in the future. From these collaborative exercises, we are investigating resources, policies, and investments needed to maintain reliable water supplies through 2045. We are developing an adaptive management strategy along with a series of performance measures and reality checks to help inform us on what plausible future we are heading towards, so that plans can be adjusted as needed.


The IRP Process: Envisioning the Future


Determine What Will Impact Our Future

Identify the uncertain factors that could challenge or benefit Southern California’s water supply.

  • Climate change
  • Economics and demographics
  • Legislation and regulations
  • Federal and state support 
  • Technological advances in water
  • Aging infrastructure 

Build the Scenarios

With these potential impacts in mind, develop four scenarios looking at how these factors could play out in each situation, promoting greater understanding of the wider range of potential outcomes.

Key drivers of change such as climate change, regulatory requirements, and the economy will have uncertain but potentially significant effects on both water supply and demands. These and many other drivers of change were identified through a collaborative process with Metropolitan’s stakeholders. The process of quantifying the impacts of these drivers within each scenario is underway. A qualitative assessment of the key drivers within each scenario is shown below:

  • Scenario A: Gradual climate change impacts, low regulatory impacts and slow economic growth
  • Scenario B: Gradual climate change impacts, low regulatory impacts, high economic growth
  • Scenario C: Severe climate change impacts, high regulatory impacts, slow economic growth
  • Scenario D: Severe climate change impacts, high regulatory impacts, and high economic growth

Conduct an Analysis

Look at the gap between expected water supplies and how much water the region will need in each scenario.  

Develop a Mix of Actions

Using insight from the gap analysis, identify solutions and policies that address the outcomes of each scenario, promoting reliability despite the uncertainty of the future.  

An Expert View

Metropolitan has enlisted the support of expert consultants in the fields of water demand and climate change to help us better understand the key drivers affecting future water reliability. These experts responded to initial charge questions from Metropolitan staff, engaged with board members and member agency staff during workshops, and continue to respond to follow up questions. Their final memos will be included in the appendices to the IRP.

Future Water Demands: What the Experts Say

Southern California’s future population growth, housing mix and economy are drivers that will have considerable influence on future demands on Metropolitan supplies. To better understand these drivers, Metropolitan enlisted five consultants with diverse expertise in these issues. On March 23, 2021, they participated in a three-hour board workshop to share insights on key influences of future water demands in Southern California.

Lisa Maddaus

Co-owner and senior water resources engineer with Maddaus Water Management Inc.

Stephen Levy

Director and Senior Economist of the Center for Continuing Study of the California Economy in Palo Alto

Dan Rodrigo

Senior Vice President and Global One Water Practice Leader for CDM Smith

Dr. Thomas Chestnut

CEO of A & N Technical Services, Inc.

Dr. Kurt Scwabe

Expert on economic issues and water use, agricultural production, urban water conservation, ecosystem services, and environmental regulation


Learn about the insights they provided:

Experts Workshop Recording (March 23, 2021)

Summary of IRP Workshop

Summary of IRP Expert Responses to Charge Questions

What Did the Experts Say? A Summary of the Water Demands Workshop


Climate Change and Water: What the Experts Say

Southern California’s water future will be profoundly impacted by our changing climate. Science can’t provide a precise answer, given how future decisions will impact future levels of greenhouse gas emissions. But experts studying climate change can provide a range of potential futures to assist Metropolitan in updating the district’s long-term water strategy. On May 25, the Metropolitan Board of Directors held a three-hour workshop to listen to four climate change experts provide insights into their research and their thoughts on prudent planning.

Dr. Heidi Roop

Assistant Professor, University of Minnesota Department of Soil, Water and Climate

Julie Vano

Research Director at Aspen Global Change Institute

Brad Udall

Senior Water and Climate Research Scientist at Colorado Water Institute, Colorado State University

Heather Cooley

Director of Research at the Pacific Institute


Learn about the insights they provided:

Experts Workshop Recording (May 25, 2021)

What Did the Experts Say? A Summary of the Climate Change Workshop

Summary of Preliminary Responses

Preliminary Responses to Charge Questions

City Scape

25 Years of Successful Planning


The year 2020 marked the conclusion of a 25-year planning cycle that was first envisioned by Metropolitan’s inaugural IRP in 1996. And Metropolitan has never been more reliable. Regional water demands are far lower than expected, thanks in large part to Southern Californians adopting and maintaining water-saving behaviors. Metropolitan has also stored a record amount of water for drought or other emergencies.

Population growth