The state’s decision this week to cut off Sacramento-San Joaquin River Delta access to thousands of farmers and water agencies highlights the need for serious and immediate conservation throughout the Bay Area and California.

It’s been obvious for months that the state faces its most serious water shortage since the historic 2012-16 drought. Bay Area water agencies should be imposing mandatory water restrictions on users now.

The Santa Clara Valley Water District declared a water shortage emergency on June 7, calling for a 33% reduction from 2013 levels. The Marin Municipal Water District on April 20 approved a plan to cut water use 40%.

But the East Bay Municipal Utility District and the San Francisco Public Utilities Commission have only requested voluntary conservation from their residents. And the Contra Costa Water District is merely asking its residents to use water efficiently.

They say they have adequate water supplies in their reservoirs. But that’s a shortsighted approach that ignores the impact of climate change on California winters. If next winter is dry, mandatory restrictions could be needed in those districts, too, for their own good and the collective preservation of the water supply for the entire region.

California also needs to conserve every drop of water possible to ensure needed supply for urban and agriculture users and protect against further destruction to critical Delta wildlife habitat. The Delta provides fresh water for 25 million Californians, including about one-third of Bay Area residents.

The State Water Resources Control Board recognized the importance of the Delta when it sent notices Tuesday to 4,300 junior water rights holders in the Sacramento-San Joaquin River Delta region warning them that access to the State Water Project and the Central Valley Project will be cut off sometime this summer.

The decision doesn’t impact the region’s 2,300 senior rights holders — yet. They might also face severe restrictions depending on water availability later this summer, the state warned.

The state’s more than 1,500 reservoirs are 50% lower than they should be this time of year. Northern California’s two largest reservoirs, Lake Oroville and Shasta Lake, are at 37% and 43% of capacity, respectively.

To be sure, while urban and suburban users urgently need to conserve, agriculture irrigation remains the biggest drain, sucking up about 75% of California’s available water supply.

The state should reject any further demands from farmers for additional supply, since it would come at the expense of the fish and other wildlife living in rivers and streams that feed the Delta. For example, additional draws from spawning grounds would decimate what’s remaining of California’s chinook salmon population, which had been making a comeback before the current drought.

No one wants to see water restrictions imposed anywhere in California. But it’s hard to work up much sympathy for farmers who tripled their almond orchard acreage over the past three decades even though they knew they might not have enough water to keep the trees alive during a drought. It takes about a gallon of water to grow a single almond in California, and 65% of the state’s almond crop is exported every year, primarily to India and China.

But those abusive practices should not be an excuse for the rest of us to waste water. The time for conservation is now, for farmers and for everyone else. Every water agency and user must do their part to use the minimum amount of water until this drought abates.