San Diego Region Well-Prepared for Water Year 2025

San Diego Region Well-Prepared for Water Year 2025

October 01, 2024

Region has sufficient water supplies ahead of an expected La Niña

Today the San Diego County Water Authority announced that the region has plenty of water to meet demands in water year 2025 regardless of the weather, thanks to regional investments in water reliability and two consecutive wet winters.

A water year is a 12-month period that extends from October 1 to September 30. Hydrologists chose October as the start of the water year because total annual precipitation reflects winter snow accumulation and summer rainfall. Precipitation that falls during a water year indicates how much water will contribute to stream flow and groundwater.

"San Diego County's water supply remains stable and reliable to support our region's people, economy, and quality of life," said Water Authority Board Chair Nick Serrano, whose two-year term as chair starts today. "As we move forward, I am committed to preserving this stability and reliability while keeping water prices affordable for all. Our focus will be on ensuring that every household and business in the region benefits from a secure, sustainable, and affordable water supply."

Despite two abundant water years in a row, a changing climate and years of drought on the Colorado River continue to impact the San Diego region and the West. These hotter and drier conditions stress water supplies. Over the past three decades, the Water Authority and its member agencies have been ahead of the curve by investing in supply reliability.

"San Diego County's water supply remains stable and reliable to support our region's people, economy, and quality of life."

Nick Serrano, Chair, San Diego County Water Authority Board of Directors

Those investments include maintaining and upgrading water infrastructure, participating in the nation's largest water conservation and transfer project, and building the nation's largest seawater desalination plant in Carlsbad - all of which have paid off during dry times.

"The investments we've made are a down payment on a sustainable water future for our region," said Water Authority General Manager Dan Denham. "We're proud of the work we've done to ensure water reliability, not just today but in the years to come."

As La Niña conditions are expected to replace El Niño conditions, the San Diego region remains prepared for the ongoing climate whiplash. During La Niña conditions, California residents can expect drier winters with reduced rainfall and snowfall, which could exacerbate drought and wildfire conditions. The latest outlook from NOAA's Climate Predication Center shows a 71 percent chance of La Niña conditions emerging this fall. Seven of the 10 La Niña events this century resulted in dry years, according to California's Department of Water Resources. However, research also suggests that as the climate grows hotter and drier, precipitation California receives will arrive in stronger storms, increasing the risk from flooding.

On the Colorado River, the Water Authority has worked collaboratively with other California water agencies as well as Arizona and Nevada on a Lower Basin voluntary conservation program. That program is intended to help stabilize water levels in Lake Powell and Lake Mead, which California depends on for its river supplies, through 2026.

The conservation effort exceeded 1.8 million acre-feet in water year 2024, maintaining Lake Mead storage at more than 8 million acre-feet, roughly the same storage volume as a year ago. Under the Bureau of Reclamation's anticipated river operations for 2025, California will not face mandated supply reductions. Additional voluntary system conservation is expected in water year 2025 to support the river, but that won't impact the amount of water available for San Diego County.

(An acre-foot is approximately 325,900 gallons, or enough water to meet the annual needs of 2.5 typical single-family households.)

Meanwhile, in Northern California, Lake Oroville and San Luis Reservoir - two key State Water Project reservoirs - have 3.2 million acre-feet in storage. Statewide reservoir storage at the end of August was 115% of average.

Meanwhile, in Northern California, Lake Oroville and San Luis Reservoir - two key State Water Project reservoirs - have 3.2 million acre-feet in storage. Statewide reservoir storage at the end of August was 115% of average.

In the San Diego region, water users will benefit from the supply reliability associated with ongoing operations at the Carlsbad desalination plant and water transfers of conserved agricultural supplies. Additionally, at the end of August 2024, member agency local surface water storage was roughly 287,000 acre-feet (129% of the historical 10-year average), and the Water Authority had approximately 89,000 acre-feet available in combined emergency and carryover storage to protect the region against drought or emergencies like an earthquake that could disrupt water imports.

For information on water-efficiency programs and rebates go here.

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