THIS JUST IN … PRESS RELEASE: State Water Board approves emergency curtailment measures for the Delta watershed

Acute water shortages prompt urgent action

From the State Water Board:

With climate change-induced drought reducing water levels in the Sacramento-San Joaquin Delta to alarming lows, the State Water Resources Control Board today approved an emergency curtailment regulation with measures to preserve stored water to protect drinking water supplies, prevent salinity intrusion and minimize impacts to fisheries and the environment.

The emergency regulation must be approved by the Office of Administrative Law and filed with the Secretary of State before it becomes effective and curtailment orders can be issued. 

Of the 6,600 water right holders in the Delta watershed, approximately 5,700 could be ordered to curtail diversions as early as this month under the authority provided by the regulation. The remainder, who hold older water rights or riparian rights, could be subject to curtailment if conditions worsen.

Without this action, the drinking water supply for 25 million Californians and the irrigation supply for over 3 million acres of farmland could be at significant risk should drought continue into next year.

“It is imperative that we move urgently to better manage the water we still have and prepare for the continuation of drought conditions,” said Board Chair E. Joaquin Esquivel. “The Delta watershed is a resource shared by agriculture, urban areas, rural towns and fish and wildlife, among many others. This decision is not about prioritizing one group over the other, but about preserving the watershed for all, implementing our water rights priority system, and ensuring we manage through this drought, especially for critical health and safety needs.”  

“Drought and climate change have delivered a serious blow to California agriculture this year, making the board’s curtailment action necessary,”  said Karen Ross, secretary of the California Department of Food and Agriculture. “To help farmers and ranchers adapt, the Governor’s California Comeback Plan provides for investments in climate smart agriculture and water resiliency programs to support communities.”

Today’s action was prompted to preserve critical water storage for future health and human safety and to mitigate the increasingly harmful environmental and economic impacts drought is causing in the Delta. The 1,153 square-mile watershed provides two-thirds of Californians with drinking water, supports 80% of the state’s commercial salmon fisheries and is an important habitat for more than 750 animal and plant species, including waterfowl, birds of prey and threatened or endangered fish such as the Delta smelt, Chinook salmon and steelhead.

“We’ve been working to maintain survivable conditions for fish and wildlife in the Delta, but water released from reservoirs is simply not showing up downstream as expected,” said Karla Nemeth, director of the Department of Water Resources, which manages the State Water Project. “If water right holders continue diversions, it will worsen salinity in the Delta and further deplete reservoirs below critical levels. Today’s actions alone won’t solve our depletion challenges, but we need to start implementing and adapting as needed.”

Ernest Conant, regional director for the Bureau of Reclamation, which manages the Central Valley Project, added, “Despite our best coordinated efforts, the projects continue to struggle to meet water temperatures needs, Delta salinity conditions, and water for public health and safety. With the extremely low inflow to our reservoirs, we are running out of reservoir storage and other tools to meet all the competing demands. We support the Board’s efforts to preserve water for later this year and for next year.”

Without curtailments, and if water diversions continue at their current pace, the following significant impacts are expected:

  • Excessive salinity: Fresh water releases from upstream reservoirs are needed to repel saltwater intrusion from the San Francisco Bay during dry months. If stored water supplies are insufficient for releases, high salinity renders water in the Delta unusable for humans and harms the environment.
  • Drinking water and farmland impacts: Upstream reservoirs are drained below critical levels, endangering the drinking water supplies for 25 million Californians and the irrigation supplies for nearly 3 million acres of farmland should drought continue into a third year;
  • Harm to fish and wildlife: Low water levels can result in habitat loss, an increase in invasive species, stress on endangered species and even extinction. Delta smelt nearly disappeared during the last drought in 2016. Warm water temperatures caused winter-run Chinook Salmon, another endangered species, to lose 95% egg mortality in 2014-15.
  • Increase in harmful algal blooms: Severe shortages contribute to harmful algal blooms in water that can be fatal to animals and young children. Consuming fish caught during a heavy bloom can also pose a health risk.

​​​​​​​Dry conditions in the Delta worsened this spring, when climate change-induced warm temperatures led to unprecedented losses of runoff to streams and reservoirs, and prompted water diverters below the reservoirs to withdraw their water earlier and in greater volumes than in previous critically dry years. This combination of events resulted in the loss of nearly 800,000 acre-feet of water, enough to supply more than one million households for a year and nearly the entire capacity of Folsom Reservoir. 

Governor Gavin Newsom declared a drought state of emergency that now covers 50 of California’s 58 counties. The governor’s executive action on May 10 directed the board to consider the emergency regulations that authorize curtailments and allowed for it to require additional information from right holders to help predict future demand and ensure compliance.


The equitable administration of California’s water rights system enhances water management in the Delta. The age and type of right, be it appropriative (acquired natural or abandoned water) or riparian (natural water connected to land), generally informs how water can be diverted during drought conditions. In times of shortage, those with more junior rights typically are required to stop diverting from rivers and streams before limitations apply to more senior right holders.

Prior to implementing the emergency regulation, the board alerted water users to the acute shortages three times within the past five months. On March 22, letters were sent to all right holders and agents in California informing them of dry conditions, encouraging planning and conservation, and requesting accurate and timely water use reporting. On June 15, notices were mailed to approximately 4,300 right holders in the Delta, urging them to stop diverting amid worsening hydrologic conditions, and warning another 2,300 claimants with more senior rights that continued drought could impact their future ability to divert. And on July 23, staff notified senior right holders in the watershed that supply is insufficient for any diversions under some pre-1914 appropriative claims or to support full diversions by some riparian claims.

The board encourages water users to collaborate on voluntary agreements that help local communities adapt to water shortages, prevent impacts to other legal water right users, and benefit fish and wildlife.

The board website contains additional information about drought, measures taken in response, the latest developments and an updated methodology that determines when water in the Delta is unavailable. Staff demonstrated the Unavailability Visualization Tool in May and held another public workshop July 27 on the emergency regulation.

On July 8, the Governor asked all Californians to voluntarily cut their water usage by 15% with simple measures to reduce water use. Tips for conserving water, such as taking shorter showers, fixing indoor leaks and installing drought resistant landscaping can be found on the Save Our Water website.  

The State Water Board’s mission is to preserve, enhance and restore the quality of California’s water resources and drinking water for the protection of the environment, public health, and all beneficial uses, and to ensure proper resource allocation and efficient use for current and future generations. 

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