The Los Angeles Department of Water and Power (LADWP) manages the water supply for the second most populous city in the United States—that’s about 4 million residents. LADWP has the critical task of ensuring that the water supply can support a growing population in the face of a changing climate.

As part of its ongoing relationship with UCLA—through a long-standing Memorandum of Agreement (MOA) stewarded by the Sustainable LA Grand Challenge—LADWP has worked with some of the nation’s leading climate researchers to tackle this critical challenge. 

The MOA has created the infrastructure to allow LADWP to easily leverage ongoing work by UCLA’s climate researchers to better inform the country’s largest municipal utility’s Urban Water Management Plan (UWMP)—the roadmap for ensuring LA has a reliable water supply—so that decisionmakers can anticipate vulnerabilities and reduce uncertainty in their planning.

“We gave [LADWP] a data deliverable of multiple climate projections catered to the LA region for their very specific data requirements to run their water demand model,” said Ben Bass, an assistant researcher focused on hydroclimate change, in UCLA’s Department of Atmospheric and Oceanic Sciences. 

As part of Professor Alex Hall’s research group, Bass works with a team to refine global climate models—powerful supercomputing programs—that simulate the long-term global climate dynamics in order to reduce uncertainty in future projections of climate change. Their work—especially when it comes to modeling temperature changes, precipitation rates, and how those factors interact—aligns perfectly with LADWP goals.

Through the MOA, Bass and his colleagues have provided LADWP with the best available data for three separate projects since 2019, each time refining and updating the data and applying it to emerging questions.

“[T]he data set we're giving LADWP…is based on the Ferrari of climate projection techniques,” said Bass. “It's state-of-the-art. It really is utilizing novel techniques for improving the global models down to a regional scale across California.”

LADWP updates its UWMP every five years and, as part of this most recent collaboration, UCLA researchers are leveraging their ongoing work to provide important data and modeling for the agency’s 2025 update. 

This work builds on a previous collaboration with LADWP in 2020, through which the research team used cutting edge climate projections to update and refine the climate change analysis relevant to the city’s Eastern Sierra Nevada Watershed—an area critical to LADWP’s operation of the LA Aqueduct and LA’s water supply in general.

 When it came time for LADWP to update the UWMP for 2025, the MOA meant the infrastructure was already in place for the agency to turn again to the Hall Research Group, building off the work from previous collaborations.

“We're also putting together a report letting [LADWP] know how that data was created, what it means, and also other information that they've asked for, like how evaporation rates will change,” he said. 

Understanding how much—and how rapidly—rising temperatures will increase the rates of evaporation in LA’s critical water sources, like the Eastern Sierra Nevada Watershed, is foundationally important for any future planning.

The MOA essentially gives LADWP access to the broader scope of work being undertaken by UCLA’s leading researchers. Through the Hall Research Group, UCLA is actively engaged in the California Fifth Climate Assessment, a statewide undertaking that brings together experts across institutions to create a holistic foundation for understanding climate risk throughout California.

“The specific data set that we're using here is based off of the California Fifth Climate Assessment,” said Bass.

The work the Hall Research Group did with LADWP in 2020 also laid the groundwork for another research effort from 2021 to 2023. That project looked at the risks posed to the LA Aqueduct system by changes in seasonal snowpack volume. 

This effort built off on one of the key findings from the 2020 project, namely that climate change will significantly reduce snowpack in the Eastern Sierra Nevadas. For their work in the 2021-2023 effort, researchers delved deeper and used advanced modeling techniques to better understand how the changes in the snowpack volume would change the seasonal timing, amount, and volume of water runoff.

LADWP leveraged this research to evaluate water system operations and water supply management plans.

Read more about the longstanding UCLA partnership with LADWP.