Current Water Supply Levels

Current Water Supply Update: Our region is still in a drought.

Read drought condition updates here.

  • Visit Current Conditions for Sonoma County to view the U.S. Drought Monitor (USDM). These graphics show the location and intensity of drought.
  • Visit California Water Watch, enter your address to see how much rainfall your local area has received to date. 
  • Conservation requirements are still in place in cities and water districts.  Please visit your local water retailer to learn more about your conservation requirements.
  • On Wednesday, May 25, 2022 Sonoma Water filed Temporary Urgency Change Petitions with the State Water Resources Control Board to establish a Critical water supply condition for both the upper and lower Russian River. Under Critical water supply conditions, the Russian River would have minimum instream flow requirements of 25 cfs and 35 cfs in the upper and lower river, respectively. If approved, this change will allow Sonoma Water to continue the minimum instream flows that the river is currently operating under and preserve water supply in both Lake Mendocino and Lake Sonoma. The current petitions also commit Sonoma Water and its retail customers to a 20-percent reduction in total diversions from the Russian River between July 1 and October 31 compared to the same time period in 2020. To read the TUCP and learn more about the drought, please visit www.sonomawater.org/tucp

Rainfall, Weather, and Streamflow Data

National Weather Service weather forecast for Santa Rosa

Current streamflow gauge reading for Russian River and tributaries - Sonoma OneRain website

Sonoma OneRain - Real-time Rainfall, River-Stream, and Reservoir Data

Scheduled releases - Lake Mendocino on CA Data Exchange Center Website

Scheduled releases - Lake Sonoma on CA Data Exchange Center Website

Precipitation map for the current Water Year (October 1 - Present)


Current Water Supply Levels for Lake Pillsbury, Lake Mendocino, and Lake Sonoma

*Note that between March 1 and September 30 in Lake Mendocino, the Water Supply Pool is allowed to encroach into the Flood Control Pool and transitions to a higher operational level for the summer season. The "Target Water Supply Curve" represents the normal daily storage level for each day of the year. The daily storage levels were determined based on reservoir modeling of an average year under “Normal” water supply conditions as designated by the Russian River System hydrologic index. Categories of water supply conditions are based on criteria defined in the State Water Resources Control Board Decision 1610. These conditions establish the applicable instream flow requirements.

Cumulative River Diversions Weekly Report

To monitor our progress on achieving the 20% river diversion reduction requirement under the June 2022 TUCO (term 12), we’ll be issuing a weekly diversion report. This plot of cumulative diversions continues the same weekly reporting implemented last summer. Below is the current week’s plot of cumulative river diversions starting July 1st, shown in comparison to baseline 2020 diversions over the same time period.

This is the last weekly report for diversion reductions as today October 31, 2022, is the last day of the compliance period for the 20% reduction requirement under Term 12 of the June 2022 TUCO. Below is the current week’s plot of cumulative river diversions starting July 1st, shown in comparison to baseline 2020 diversions over the same time period. Cumulative reductions are at 30.5% with a total diversion reduction volume of 2,185.2 MG.


About Lake Sonoma and Lake Mendocino

Sonoma Water is the local cost-sharing partner for Lake Mendocino and Lake Sonoma, and determines the amount of water to be released from each reservoir when the lake levels are in the water supply pools. The U.S. Army Corps of Engineers determines the amount of water to be released when the lake levels are above the water supply pools and in the flood control pools.

Lake Mendocino relies on year-to-year rainfall to fill as well as water diverted from the Potter Valley Project. Lake Mendocino is a key drinking water source for the cities of Ukiah, Healdsburg, Cloverdale and Hopland, and also provides water to Sonoma Water’s Russian River water supply system. Water releases from Lake Mendocino support flows in the Russian River for the threatened Chinook salmon and steelhead trout during the fall and winter seasons. 

Lake Sonoma is about four times larger than Lake Mendocino and can provide multiple years of water supply. Lake Sonoma relies on rainfall to fill and supports a dynamic and fragile ecosystem in Dry Creek that includes the endangered coho salmon and threatened steelhead trout. Lake Sonoma provides a majority of Sonoma Water's service area with its drinking water.

The Russian River is a managed river system with reservoir releases controlling river flows, especially throughout most of the summer and fall. When tributary stream flows are low, Sonoma Water releases water stored in the reservoirs to supplement the natural flows in the Russian River to provide adequate flows for water supply, recreation and aquatic habitat. A release from a reservoir can be categorized as being of ‘pass-through water’ or ‘stored water’. The term ‘project water’ is often used instead of stored water and is used to describe water that is present because of the dam and reservoir project. Pass-through water is water flowing into the reservoir that is not stored in, but passes through, the reservoir. Project water releases to supplement the natural flows in the Russian River and Dry Creek are necessary to meet mandatory minimum streamflow requirements that exist for both of these watercourses.