SACRAMENTO, Calif.  | Thu Apr 9, 2015 12:47am BST

Broad rivers fed by Sierra Nevada snowmelt brought plentiful water to California's agricultural heartland and a certain sense of entitlement.

So strong was the belief that water was an inalienable right that several communities and cities promised never to install meters to measure water use - a jarring idea today in a state suffering from a prolonged drought and mandatory cuts to water consumption.

More than a quarter of a million households and businesses can use as much water as they want, taking leisurely showers and keeping lawns a lush green, without paying a penny more on their bills each month, simply because they have no meters, state data show.

"We've cut back quite a bit," said Kim Matisevich, 48, who lives in the affluent - and unmetered - community of Arden Park just outside of Sacramento, pointing to an area toward the back of her family's half-acre lot that was visibly drier than the green front lawn.

"But the front yard is a representation of who lives in the house."

Like others here, Matisevich is not sure how much she pays for water - it is a flat rate included in the sewer bill - or which of the 20-some minor utility companies serving the region provides it to her home.

About a hundred years ago, when urban water systems were being developed throughout the state, the city of Sacramento wrote protections from metering into its charter, vowing that residents would always have the right to use as much water as they needed.

But a series of droughts in recent decades led to concerns that unmetered water use would slow down conservation efforts, and in 2004, the state legislature passed a law requiring utility companies and water districts to install meters by 2025.

On Tuesday, the state's top water regulators released a framework for enforcing California's first statewide mandatory restrictions on urban water use - cuts of 25 percent for non-agricultural users ordered last week by Democratic Governor Jerry Brown as a devastating drought enters its fourth year.

It is not clear, however, how that order can be enforced in cities and towns, many of them in the fertile San Joaquin Valley, still lacking meters that allow utilities to track usage - and bill accordingly.

'FRONT YARD MIGHT GO'

The Sacramento County Water Agency, which provides water to Arden Park, is working to install meters in its territory to comply with the state law.

In the state capital of Sacramento, 61,000 water customers remain unmetered - just under half of the total households and businesses in town.

"Half the city is still on a flat rate, and we have no way of knowing how much water they're using," said Bill Busath, interim director of the Department of Utilities for Sacramento, home to 480,000 people and the state's sixth-largest city.

By the end of next year, Sacramento will have spent $145 million installing meters - and still have nearly 40 percent of its water customers unmetered, he said. Other cities still working to install meters include Bakersfield and Merced.

Not surprisingly, cities say conservation has gone up after meters have gone in.

By the end of 2014, a year after Fresno finished installing its meters, water consumption in the city had dropped by 27 percent from 2008, the year before the project began, said city spokesman Mark Standriff.

In Los Angeles, residents who have been on meters for decades pay a base rate for a modest amount of water that the city deems necessary to maintain a property, and then pay at higher rates for additional water, said Department of Water and Power spokesman Joe Ramallo.

The median monthly bill in the city is $58, meaning that half of residents and businesses pay less and half pay more. But those with larger properties who choose to maintain big lawns pay much more - $134 per month or more for those who are in the top 10 percent of water users.

In Arden Park, Matisevich said she and her husband try to conserve, watering more generously only in the front and in the part of the back yard close to the house where people gather to relax for barbecues.

If the neighborhood gets put on water meters, they might have to rethink that, Matisevich said.

"The front yard might have to go, and become Astro Turf," she said.