Summer 2026 Water Supply Findings and Outlook

Kevin Hostert, Senior Water Resources Analyst, Municipal Water District of Orange County
June 22, 2026

Spring 2026 brought extraordinary weather conditions across the western United States. Following a record-breaking March heatwave that rapidly melted much of California’s snowpack, the California Department of Water Resources (DWR) reported no measurable snow during its April 1 Phillips Station snow survey, only the second such occurrence in the state’s recorded history. While the disappearance of California’s “frozen reservoir” is concerning, strong reservoir storage and regional planning efforts continue to ensure reliability of Southern California’s water supplies. Below is an updated snapshot of the major factors influencing water supply conditions as we move into the summer of 2026.

1. Orange County’s Local Water Supply Remains Strong

Despite extremely low statewide snowpack, Orange County’s local water supplies remain in excellent condition. Rainfall received during the winter and early spring helped recharge local groundwater supplies and reduce outdoor water demand. The Orange County Groundwater Basin, which provides approximately 85% of the water supply for North and Central Orange County, remains at healthy operating levels and continues to serve as the region’s primary source of water reliability.

Local investments in groundwater management, water recycling, and conservation have significantly reduced dependence on imported water during dry periods. At this time, no groundwater supply shortages or imported replenishment needs are anticipated.

2. State Water Project Supplies Improve Despite Low Snowpack

While snowpack conditions deteriorated rapidly this spring, California’s reservoir storage remains exceptionally strong. Following additional spring storms and runoff, DWR increased the 2026 State Water Project (SWP) allocation from 30 percent to 45 percent in May. Statewide reservoir storage is currently above average for this time of year, with Lake Oroville nearing full capacity.

The strong reservoir conditions are largely the result of precipitation that fell as rain rather than snow during the winter season. Although this provided immediate runoff and storage benefits, it highlights a growing challenge for California’s water system: less snowpack means less natural water storage available for release throughout the summer months.

For Southern California, the increased SWP allocation improves imported water supply reliability and reduces the likelihood of significant drawdowns in regional storage reserves during 2026.

3. California Snowpack Reaches Historic Lows 

The most significant water supply concern entering summer 2026 is the unprecedented loss of snowpack throughout California and much of the western United States.

The statewide snowpack peaked weeks earlier than normal and had largely disappeared by April 1 following record March temperatures. By mid-May, statewide snowpack conditions had fallen to approximately 12% of average. The Northern Sierra, which provides runoff to many of California’s largest reservoirs, recorded some of its lowest snowpack conditions on record.

Although reservoirs remain healthy this year, the lack of snowpack removes an important source of delayed runoff that typically sustains water supplies through the summer and early fall. If dry conditions persist into 2027, California could face renewed drought concerns more quickly than reservoir storage levels alone might suggest.

4. Colorado River Conditions Continue to Worsen 

The Colorado River remains the greatest long-term challenge facing Southern California’s imported water supplies.

Runoff forecasts for the Upper Colorado River Basin have worsened considerably since the beginning of the year. Following an exceptionally warm and dry winter, forecasted inflows into Lake Powell are among the lowest on record. Water managers now project Colorado River runoff to be substantially below average, placing additional pressure on both Lake Powell and Lake Mead.

At the same time, negotiations among the seven Colorado River Basin states regarding post-2026 operating rules remain unresolved. The basin states failed to reach agreement on a long-term management framework earlier this year, increasing the likelihood of federal intervention in determining future river operations.

While Southern California’s water agencies continue to benefit from decades of investments in storage, conservation, water recycling, and transfer programs, the long-term outlook for the Colorado River remains uncertain and will require continued regional cooperation and adaptive management.

Outlook for Summer 2026

Despite historic snowpack losses and ongoing Colorado River challenges, Orange County enters summer 2026 with a reliable and diversified water supply portfolio. Healthy groundwater conditions, strong statewide reservoir storage, and increased State Water Project allocations provide a stable supply outlook for the remainder of the year.

However, this year’s conditions also serve as another reminder of California’s changing hydrology. More precipitation is falling as rain rather than snow, reducing the natural storage provided by the Sierra Nevada snowpack. Continued investments in water storage, groundwater recharge, water recycling, conservation, and climate adaptation will remain essential to maintaining long-term water supply reliability.

Want to see how MWDOC monitors water supply conditions? Explore MWDOC’s Water Supply Report to access the latest information on statewide and local water resources, including precipitation, reservoir storage, imported water conditions, groundwater levels, and water demand trends.