SAN FRANCISCO (AP) _ Some call themselves ''drought busters,'' others prefer ''water cop.'' But the people caught sprinkling and hosing when they shouldn't have far less flattering names for the officers hired to enforce California's water rationing.

''A woman I caught with her sprinkler running into the gutter got so mad at me she wrote my boss and said I was a 'water witch,' '' said Rene Frenken, whose title with the city of Palo Alto is ''gush buster.''

Frenken, who patrols the city just south of San Francisco by bicycle, would rather be known as a ''water cop.''

She and others are taking to the streets from San Francisco to Los Angeles in patrol cars, on motor scooters and bicycles enforcing water rationing during one of the worst droughts in California history.

The drought, now in its fifth year, is a year short of being the state's longest dry spell. A drought that began in the late 1920s lasted six years.

Frenken, like more traditional police officers, says she can sniff out the crimes.

''In the summer time, when it's really dry, I can smell the water,'' she said. ''When there's moisture in the air, you can sense it. And I keep my ears open for the sound of sprinklers.''

Frenken's fellow gush buster, Max Killen, says the job is not easy.

''One time an elderly woman just kept screaming and screaming at me, and all I wanted to do was tell her her sprinkler was on,'' said Killen, who patrols on a moped.

Like a regular cop, Killen has plenty of informants, and he also answers plenty of false-alarm calls.

''We get a lot of calls from people ratting on their neighbor,'' he said. ''Most of the time we go out and find nothing. They just call to get people in trouble.''

Penalties vary from city to city, but fines for first-time water wasters are generally about $50.

Offenders in some cities, such as Redwood City and Palo Alto, also face reductions in their water supplies.

Palo Alto gush busters installed a flow restricter - which halves the water flow - on one house whose owner left town for months after setting his automatic sprinklers to come on every day, rain or shine.

In such a case, the homeowner is billed up to $300 for installation and removal of the restricter, said Frenken's boss, Debbie Katz.

In Los Angeles, ''drought busters'' who cruise neighborhoods in patrol cars have issued more than 12,000 citations, mostly for watering during forbidden hours.

After four citations, the city can turn off a customer's water supply for two days.

''Our purpose, though, is to be educational, not confrontational,'' said Jim Derry, Los Angeles Department of Water and Power spokesman.

Oakland water cops also emphasize education ''because we need the cooperation of the community,'' said Dick Bennett, water conservation administrator for the East Bay Municipal Utility District.

Bennett said he thinks his district, with 1.2 million water users, was the first in the state to employ water cops.

''We started in 1987 and now have six full-time water watchers,'' he said. ''We give out packets of information to water wasters.''