OCEANSIDE -- "But I only had one drink!"

Officers are used to hearing that refrain from shocked motorists pulled over for driving under the influence, California Highway Patrol Lt. Mike Maas said.

Often, though, drivers' blood-alcohol level -- and erratic driving patterns -- prove their memory wrong.

"A lot of folks feel they're safe to drive and they're not," Maas said.

So far this holiday season, more drivers are taking to the roads after a few too many drinks. From Dec. 21 to Christmas Day, Highway Patrol officers made 118 arrests for driving under the influence in San Diego County, compared with 106 arrests last year. Statewide, they made 1,661 arrests, up from 1,351 last year.

More strikingly, alcohol-related traffic deaths jumped from 28 last year to 43 this year over the Christmas holiday statewide, including four in San Diego County. That's not counting the Dec. 15 alcohol-related, quadruple-death accident on Highway 76 in Pala, which happened before the official holiday season.

To avoid an encore performance over New Year's, officers are stepping up patrols and urging motorists to plan a ride home before they head out for the night.

At least 80 percent of available Highway Patrol officers will be on duty during the four-day New Year's holiday, Maas said.

On New Year's Eve, at least 20 Highway Patrol officers will be on San Diego roads, while at least 33 will be roaming the rest of the county, Officer Eric Newbury of the Oceanside office said.

They will be assisted by beefed-up patrols and checkpoints by sheriff's deputies and police departments.

In addition, the Sheriff's Department has suspended its quick-release program for DUI offenders. Drivers charged with misdemeanor driving under the influence must post a $2,500 bail -- or sit in the county jail until their arraignment on Wednesday.

To avoid a meeting with one of the officers, revelers are encouraged to plan a ride home ahead of time. As usual, cab, bus and automobile clubs are offering safe rides home (see "Safe Rides").

"Designate a driver," Maas said. "Please, plan ahead."

Runs the gamut

Los Angeles Lakers owner Jerry Buss got a DUI in Carlsbad in May. Rincon Band fire Chief Gerad Rodriguez got pulled over earlier this month on suspicion of drunken driving.

"It seems to permeate every segment of society," Maas said. "There really is no one profile socioeconomically or ethnically."

Defense lawyer Cole Casey of San Diego, who specializes in drunken-driving cases, described most of his clients as "successful professionals, or young people on the path to being successful, who are usually shocked" at the arrest.

The shock only grows when the bills start coming, and coming, and coming.

Maas said the average first-time drunken-driving arrest in San Diego County ends up costing about $10,000, after court costs, higher insurance premiums and other expenses.

Holiday weekends involving three consecutive nonwork days tend to yield the most arrests for drunken-driving, Maas said.

Surprisingly, the New Year's holiday typically isn't among the worst, he said, largely due to public-awareness campaigns aimed at motorists. In particular, arrests and fatalities over the past five years have held steady or declined, he said.

"Most people are smart enough not to drink and drive on New Year's Eve," Casey said.

But the story is much different in the days and weeks leading up to Christmas.

"What we see most is infrequent drinkers at Christmas gift exchanges, or at the once-a-year company Christmas party," he said. "They have a few drinks and think nothing of driving home."

Often, he said, a hard lesson follows: "It doesn't take much to get you over the legal limit."

How much is too much?

Escondido police Officer Steve Braucht painted drunken-driving in black-and-white terms.

"If you drink, don't drive," he said.

But Maas acknowledged that people may feel pressured to drink, especially on New Year's Eve.

"If you're going to toast the New Year and plan to drive home, make it one and only one glass of champagne," he said.

A six-ounce glass of champagne, given at least an hour to settle before taking the wheel, usually will not land an adult over the state's legal impairment level of .08, Maas said.

But it doesn't mean that it won't get you arrested for driving under the influence.

"The law allows (the police) to go ahead and charge drivers even if they're not over the legal limit, and they do," said Casey. "They can charge you based on your level of impairment, having nothing to do with your (blood-alcohol) number."

Any amount of alcohol can impair a driver's reasoning and coordination, decrease alertness, delay reaction time and impair vision and hearing, according to the medical Web site mayoclinic.com.

Alcohol affects people in dramatically different ways, the site says, depending on:

• Weight: Higher weight generally means more water in your blood, which dilutes the alcohol and lowers your blood alcohol level.

• Age: Older adults process alcohol less efficiently, meaning they generally get drunk more quickly and stay drunk longer.

• Sex: Women process alcohol differently than men and are generally smaller, so it takes less alcohol and less time to get drunk.

Other factors -- the strength of the alcohol, how quickly it is imbibed and what a person has eaten -- also affect a person's impairment, the site says.

"The best way to go," Braucht said, "is the zero-tolerance policy."

Contact staff writer Dan Simmons at (760) 740-5426 or dsimmons@nctimes.com.

Safe Rides

Key numbers to keep you -- and the roads -- safe:

(800) 400-4222: Call this number and say, "I need a tipsy tow" if you've had too much to drink. The Automobile Club of Southern California is offering to give you a ride home -- and tow your car -- up to seven miles for free. It's available from 6 p.m. today until midnight Tuesday. The service is open to everyone, including nonmembers.

(760) 722-4214: Call this number, Yellow Cab of North County, for a safe ride home. It will cost you, but not as much as $10,000 or more for a drunken-driving arrest.

911: Authorities are encouraging people to report any erratic, dangerous driving on the roads.