FILE -- In this July 9, 2014 file photo a woman works among drought-tolerant plants in her front yard in San Diego. Water use in San Diego plunged 24 percent in June well past it's target of 16 percent. (AP Photo/Gregory Bull, file)

SACRAMENTO, Calif. - California's unprecedented system of mandatory conservation imposed on cities got off to a strong start with water use plunging 27 per cent in June, regulators said Thursday.

Data released by the State Water Resources Control Board showed 265 of 411 local agencies in California hit or nearly reached savings targets.

The governor ordered cities to reduce water use by 25 per cent to prepare in case California's four-year drought persists.

The savings came during the hottest June on record, which would normally lead to an uptick in water use. Prior savings have occurred during unusually wet months

"The June numbers tell a story of conscious conservation, and that's what we need and are applauding today," said Felicia Marcus, chairwoman of the water board. "We need to save as much as possible. That is water essentially in the bank for a future dry year or more."

The report confirmed figures previously released by California's largest cities, including Los Angeles, San Diego, San Jose and San Francisco, showing strong water conservation.

The agencies that met or came within 1 per cent of their mandatory water conservation target serve 27 million Californians.

Under water board regulations for mandatory water savings, communities have nine months to hit assigned conservation targets as high as 36 per cent. Water savings are compared to 2013, the year before Brown declared a drought emergency.

Some agencies opposed the targets, saying they were unfair and unrealistic and didn't give enough credit for prior conservation efforts.

Many that objected managed to reach their targets anyway, including San Diego which saved 24 per cent in June.

Robyn Bullard, a spokeswoman for the public utilities department, credited widespread messaging that included an email blast to customers and television commercials.

The water board is separately telling thousands of farmers that there is not enough water available to divert from rivers and streams under their rights.

Multiple irrigation districts have been challenging the curtailment in court.

A Sacramento County judge indicated at a Thursday hearing that she would side with the state's new approach to warning of insufficient supplies after she ruled that earlier notices violated farmers' rights.

Summer is peak water use season, and strong residential conservation could continue through July because of record rainfall in Southern California.

The water board says it will contact every agency that didn't come close to its targets and ask for more information about what it's doing to conserve.

The worst performers, which include the water districts serving wealthy areas in the desert's Coachella Valley and Temecula in Riverside County, will be told to ramp up water waste enforcement or limit days that residents can water lawns.

Regulators have the power to impose fines on agencies that consistently miss targets, but they say that's a last resort.

Water waste enforcement also shot up drastically in June. Agencies issued more than 9,500 penalties compared to about 1,900 in May.

Meteorologists say a wet California winter is increasingly likely as a strong El Nino condition builds in the Pacific Ocean, although it's unclear if it will be a drought-buster.

A study released by the National Aeronautics and Space Administration says precipitation in California since 2012 was 20 inches short of normal, equivalent to losing a full year of rain.

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News from © The Associated Press, 2015