New Partnership Expands Water Supply Security In Southern California

San Diego – The San Diego County Water Authority and Eastern Municipal Water District have reached a new long‑term water supply agreement – the second major regional partnership announced by the Water Authority in 2026. This latest arrangement expands a growing effort among Southern California water agencies to coordinate resources, strengthen drought preparedness, and make more efficient use of existing water supplies.

The Water Authority and EMWD collectively support more than 4 million residents in San Diego and Riverside counties. Leaders from both agencies said regional cooperation is essential as climate variability and economic pressures reshape long‑term planning and underscore the need for fresh approaches that sustain water affordability and reliability.

“When I became Chair, I committed to bring new, innovative solutions to the table to match the moment we’re in with ratepayer affordability as our North Star,” said Water Authority Board Chair Nick Serrano. “This partnership is exactly that: practical and common-sense regional cooperation that strengthens reliability and creates real value for ratepayers.”

Under the new partnership, EMWD will ramp up to receiving 10,000 acre‑feet of water each year for the next 21 years. EMWD is also securing an advance of roughly 30,000 acre‑feet for later delivery – a strategic tool that gives the district greater flexibility during dry periods and reduces long‑term supply risks.

For the Water Authority, the agreement will generate an estimated $74 million over the first five years, including upfront payments. These funds will help minimize wholesale water rate pressures while ensuring the region continues benefiting from decades of investment in supply diversification.

The Water Authority’s current draft Urban Water Management Plan confirms that the agency’s diversified portfolio of water supplies, combined with a sustained commitment to water-use efficiency, will meet the region’s water needs at least through 2050, even during multiple dry years. That means the Water Authority can continue providing reliable water for San Diego County while making the most of long‑term investments through agreements like the one with EMWD.

“Affordability and reliability go hand‑in‑hand,” said Water Authority General Manager Dan Denham. “This new agreement shows that when agencies share resources and expertise, we can deliver greater value for our customers. EMWD has been an exceptional partner in advancing a more resilient and innovative water future.”

EMWD and the Water Authority worked collaboratively to develop the agreement, reflecting a shared commitment to the health and resilience of Southern California’s water system. EMWD leaders said the new supply arrangement supports long‑term planning for one of California’s fastest‑growing service areas. The district gains access to dependable supplies without the expense or timelines associated with constructing new major infrastructure.

“Regional cooperation is essential for a stable water future,” said EMWD Board President Stephen J. Corona. “This agreement highlights how collaboration can generate benefits well beyond our service boundaries.”

“Dan Denham and I have been discussing a vision for our collective water future for many years,” said EMWD General Manager Joe Mouawad. “This agreement is the first step of many towards effective regional collaboration, which is key to positive outcomes for EMWD customers as well as those in San Diego, and around Southern California.” 

Like the March agreement between the Water Authority and Western Municipal Water District, water deliveries for EMWD will move through existing facilities operated by the Metropolitan Water District of Southern California, meaning water will be conveyed using current pipelines and treatment systems. This approach avoids the need for new construction and enables the transfer to be implemented quickly and efficiently.

“When Metropolitan and the Water Authority settled their long-running legal dispute last year, it opened up a new era of collaboration, making possible agreements like this one,” said Metropolitan board Vice Chair Michael Camacho. “By working together and thinking beyond our own political boundaries, we can forge smart solutions to ensure all Southern California communities have reliable water despite the ongoing challenge of climate change.”

The water transfer partnerships are part of a broader effort to modernize water management across the Southwest and Southern California. In addition, the Water Authority has committed to developing a pilot program that could result in transferring locally produced desalinated seawater to Colorado River Basin partners in other states – another step toward a more flexible and interconnected regional water network.