DEL MAR, Calif. -- Del Mar lifeguards have tools such as Zodiacs, surfboards and ATVs, to make their job easier.

This holiday weekend, they will be testing a new tool.

"It looks like a flashlight but it actually has an alcohol detection system built into it," said Del Mar lifeguard Chief Patrick Vergne. "OK so as, an example, the officer could ask to check the drink. (The officer) basically puts it over the drink and the bar goes from green, orange to red. That detects alcohol, and means there's alcohol in the beverage."

In Del Mar, the only place to legally have a drink is at one of the beachfront restaurants. The city has banned booze from its beaches for the summer in hopes of discouraging unruly crowds.

Gilbert Salom comes to Del Mar every year for the holiday weekend, but he and his friends understand the beach is off limits when it comes to Happy Hour.

"If they're going to be having a drink, they better be doing it well over there away from me," said Salom.

With the help of modern technology, beachgoers might not be fooling anyone when trying to disguise drinks in a red plastic party cup.

"It's a way to out-sneak the people who are sneaking in their alcohol," said Vergne.

Alcohol is illegal on every beach in San Diego County, except for the Silver Strand Beach in Coronado.

Beachgoers who break the law will be issued a $250 citation.

Repeat offenders could face a fine of $1,000 and up to six months in jail.