On holiday weekends, over spring break and throughout the summer, Pismo Beach's population sometimes triples as tourists flock to the beach town.

As they fill hotel rooms and vacation rentals, the visitors stuff Pismo Beach's coffers with hotel tax and sales tax revenue.

But some vacationers also contribute to the city's revenue in another way: fines paid for drunken-driving arrests.

A Tribune review of drunken-driving arrests during a nearly three-year period between 2008-11 shows that 40% of those arrested in Pismo Beach on suspicion of driving under the influence live outside San Luis Obispo County -- including many from the Valley.

When compared to the number of DUI arrests in other cities in San Luis Obispo County, the numbers also show that Pismo Beach has the highest rate of DUI arrests in the county, at 76 per 1,000 people.

It's unclear exactly why Pismo Beach has more arrests than some of its neighboring cities, but one possibility is the city's meal ticket: tourism.

Pismo Beach's population is 7,655, but on certain weekends and holidays, more than 30,000 people, and some say as many as 70,000, flood the city for car shows, the Fourth of July holiday and other events.

Also, those coming to work in the city's hotels, restaurants and other services push the Police Department's daily "service population" to about 16,000 people, said Pismo Beach Police Cmdr. Jake Miller, who heads up patrol operations.

"We certainly don't want them [out-of-town residents] to think at all that we're targeting them," Miller said. "We treat the violation of driving under the influence the same no matter where you're from."

Of the 586 people arrested on suspicion of driving drunk in Pismo Beach over a 32-month period, about 14% live in the San Joaquin Valley, including Fresno, Bakersfield, Visalia and Clovis.

Of the locals arrested, about 16% live in Pismo Beach.

San Luis Obispo Superior Court officials, who distribute the revenue from fines to the cities, aren't able to break down the exact amount of money Pismo Beach receives from DUI fines, which makes up only a small percentage of Pismo Beach's overall budget. The city's largest source of revenue is the transient occupancy tax, or bed tax, paid by those who stay in the city's motels, vacation rentals and RV parks. The city expects to bring in about $6 million in TOT this year.

In past years, police have partnered with local bars and restaurants to try to reduce drunken driving by offering designated drivers free nonalcoholic beverages.

During this April's Taste of Pismo event, which features food from 20 local restaurants and wine from about 35 wineries, designated drivers will be charged only half the admission price, said Peter Candela of the Pismo Beach Chamber of Commerce.

"We often run into people who are coming to the city [who] almost feel like, 'We're in Pismo, so there are no rules,' " said officer Bill Garrett, who has been recognized four times by Mothers Against Drunk Driving for making the most DUI arrests in the city.

He believes Pismo Beach's arrest numbers could be due to a combination of factors, including its tourist population and some officers' increased efforts to get drunken drivers off city streets.

Last Wednesday night, officer Adrian Souza steered his patrol vehicle around downtown streets and parked near the intersection of Price Canyon Road and Price Street. About 11:25 p.m., Souza and other officers stopped to talk to a younger man found asleep in his truck at Chumash Park. A breathalyzer test showed him to be over the legal limit, and Souza warned him to stay put for at least another hour before driving.

A little later in the evening, Sgt. Shawn Singleton spotted a white SUV heading south on Highway 1 in the bike lane -- a sign that the driver may be intoxicated.

Singleton pulled the SUV over in Oceano, and waited for Souza to arrive and administer a field sobriety test. The driver, a Visalia resident heading to the beach, followed a series of tests, and then blew into the breathalyzer before being arrested.