CALIFORNIA RESERVOIR REPORT

Last Updated: December 22, 2025

California's dam and reservoir system is currently experiencing a mix of conditions, with some reservoirs reporting above-average storage levels while others are showing signs of depletion. Notably, Lake San Antonio's storage is nearly double its average at 270,863 acre-feet, reflecting a significant boost likely due to recent heavy rains and flooding incidents across Northern California. Conversely, Bear Reservoir's storage is alarmingly low at just 2 acre-feet, suggesting a critical water shortage. The atmospheric rivers and the powerful Christmas storms have brought substantial precipitation, causing flash flooding and impacting travel plans, but also contributing to increased storage in some reservoirs.

However, these abnormal conditions can be partially attributed to one of California's worst snow droughts since 2001, as reported by E&E News. The lack of snowpack affects the gradual replenishment of reservoirs and river flows, which is a key natural water storage mechanism. With the Colorado River negotiations revealing water use problems and no long-term agreement in sight, the state's reliance on reservoir storage is heightened. The situation is exacerbated by climate change, leading to more frequent dust storms and extended flood threats from atmospheric rivers. Even as some reservoirs like New Bullards Bar and Lake Crowley are experiencing significantly high storage levels, the overall hydrological balance is precarious due to fluctuating weather patterns and the broader challenge of aridification in the region. The recent incidents of flooding and increased rainfall have provided temporary relief but do not offset the broader concerns regarding long-term water sustainability in California's reservoir systems.

California has over 1,400 reservoirs and dams, which provide water for agriculture, industry, and households. Some of the major reservoirs in the state include Lake Oroville, Shasta Lake, and San Luis Reservoir. These reservoirs are fed by streams, rivers, and creeks such as the Feather River, Sacramento River, and San Joaquin River. The snowpack in the Sierra Nevada mountains is a crucial source of water for these reservoirs, as it melts during the spring and summer and fills the streams and rivers that flow into the reservoirs. However, drought conditions have been a major concern in recent years, with record low levels in some reservoirs. Seasonal trends show that reservoirs are typically at their lowest levels in the fall and winter, and reach their highest levels in the spring and summer. Overall, California’s reservoirs and dams play a vital role in managing the state’s water resources and ensuring a reliable water supply for its residents.

California has over 1,400 reservoirs and dams, which provide water for agriculture, industry, and households. Some of the major reservoirs in the state include Lake Oroville, Shasta Lake, and San Luis Reservoir. These reservoirs are fed by streams, rivers, and creeks such as the Feather River, Sacramento River, and San Joaquin River. The snowpack in the Sierra Nevada mountains is a crucial source of water for these reservoirs, as it melts during the spring and summer and fills the streams and rivers that flow into the reservoirs. However, drought conditions have been a major concern in recent years, with record low levels in some reservoirs. Seasonal trends show that reservoirs are typically at their lowest levels in the fall and winter, and reach their highest levels in the spring and summer. Overall, California’s reservoirs and dams play a vital role in managing the state’s water resources and ensuring a reliable water supply for its residents.