More than 125 California agricultural users with senior water rights and thousands upon thousands of acres under their control have been ordered to stop siphoning water from two of the state’s key rivers, as the drought moves into the summer months with no rain expected.

This is the first time in almost 40 years that senior users, whose claim to the water dates back more than 100 years, have seen curtailments. California’s complex water rights system was codified in law in 1914. At that point, and moving forward, many new water rights were established. Senior water rights predate that historic agreement.

On Friday, June 12, the California State Water Resources Control Board announced that there is insufficient water available for senior water right holders with a priority date of 1903 or later in the San Joaquin and Sacramento watersheds and the Delta. The announcement noted that the need for further curtailment of more senior rights and curtailments in other watersheds is being assessed weekly.

Violators of the new order are subject to fines up to $1,000 per day and $2,500 per acre-foot of water unlawfully diverted. They also face cease-and-desist orders, or prosecution in court. Senior water right holders with priority dates earlier than 1903 in the affected watersheds can continue to divert water in accordance with their current right. Riparian water rights, which refer to land that abuts these rivers, was not affected.

In its notice, the board said: “Today’s action is based on reported diversion demands, estimates of natural flows and actual stream flows. Conditions in these and other watersheds continue to be monitored, and curtailment notices for other watersheds and for more senior water right holders in these watersheds may be imminent.”

While these users can tap groundwater if they have access via a well, the state agency did warn that “groundwater resources are significantly depleted in some areas.”

This curtailment of these water deliveries was not unexpected. Earlier this year, the State Water Board issued curtailment notices for all post-1914 water rights in the Sacramento and San Joaquin River watersheds and the Delta.

In May hundreds of Delta growers negotiated a voluntarily cutback in Riparian rights in exchange for no further curtailment as the summer progresses. Riparian water right holders had until June 1 to elect to participate in the voluntary program. Reportedly about half of these farmers took the deal.

Currently, more than 9,000 junior and senior water right holders in the Sacramento-San Joaquin River watersheds and the Delta have been notified that there is insufficient water in the system to serve their rights.

The board has announced that “it is expected that more senior rights will be subject to curtailment.”

Though weather models do predict that current El Niño conditions in the Pacific Ocean point to a greater possibility of late summer/early fall rain in the West, California typically gets no rain during the summer months.

The State Water Board has said that it will lift the curtailments as supply increases in the fall or winter.

There is no way to quantify how these curtailments affect growers, as every grower’s situation is different. Some have wells and some do not. And some have older senior rights to fall back on and some have Riparian rights.

It was estimated that in 2014 more than 500,000 acres were fallowed in California because of the drought. Some are estimating that number at more than 620,000 for this year. The majority of acres fallowed would be in field crops, but the drought has definitely taken its toll in fresh produce production.

The acreage in both the San Joaquin Valley cantaloupe and mature green tomato crops are said to be down about 10 percent this year, directly due to the drought conditions.