California governor Jerry Brown on Wednesday ordered cities and towns in the drought-stricken state to cut their water usage by 25 per cent, as the area faces its fourth straight year of shortages.

The decision to require a statewide cut in water usage is the first in California’s history and came just hours after scientists said they had found “no snow whatsoever” in regular tests in the Sierra Nevada mountains. The snowpack, an important source of water for the state during the summer, is typically at its peak this time of year.

“Water conservation must become a way of life during the worst drought in most Californians’ lifetimes,” Mr Brown said.

In January 2014, he declared a drought emergency and called for the public to reduce water usage by 20 per cent. A year on no more rain has fallen, but the state has managed to cut water use by only an average of 11 per cent, according to research by the Public Policy Institute of California.

“People have cut back, but the problem we all face is the drought is worse so we’ve got to step it up,” said Steve Ritchie, assistant general manager for water at the San Francisco Public Utilities Commission.

The cuts to urban water usage will mainly limit cities’ and residents’ ability to carry out outdoor landscaping, and not limit the availability of drinking water or its use for household tasks like bathing or laundry, experts and officials said. The order requires the cuts to be made by next February and takes 2013 as the baseline against which the 25 per cent reduction is measured.

The order includes a ban on using drinking water to irrigate ornamental landscaping on public streets. The state will also encourage and provide funding to get residents to replace their grass lawns with less water-thirsty alternatives in so-called “cash for grass” programmes that are already in place in many cities.

With green lawns still a hallmark of many a south Californian mansion or suburb, cutting back there could go a long way towards reaching the required reduction, water experts and officials said. Landscaping is estimated to account for around half of urban water usage, said Ellen Hanak, a water expert with the PPIC.

However, the order does not require cuts from farmers, who together are the largest consumers of California water and a major economic powerhouse in the state. While some environmentalists have pushed for limits on farmers’ ability to plant water-hungry crops like rice and almonds, said Ms Hanak, it is more politically and economically challenging for the government to place new limits on commercial operations.

“It would be really dangerous for the government to try to micromanage crop choices by farmers,” she said. “Those are business decisions about commodity production. It’s different from whether or not we have lawns.”