Sheriff's deputies patrol 4th of July partying on Discovery Bay Delta

DISCOVERY BAY, Calif. (KGO) -- It's one of the biggest party days of the year on the Delta and potentially one of the most dangerous.

Hundreds of boats head out from places like the Discovery Bay Yacht Club, seemingly all at once, to enjoy the day.

"I think it's fun, you want to be around people," said boater Sarah Hoffman. "Everyone's wearing their red, white and blue."

But in some cases, all the fun can turn tragic.

That's where the Contra Costa County Sheriff's Marine Patrol comes in.

Their goal is to make sure that what's happens out on the Delta stays under control.

"We're looking for violations of the Harbors and Navigation Safety Code, county ordinances, or rules of the road, basically unsafe acts out here," explained Deputy Doug Powell.

That includes making stops, for instance for going a little too fast in a particular area.

"The zone you came through way before the bridge, that's all five miles an hour," Powell explained to one boat driver he "pulled over" on the water.

It's also an opportunity for the deputies to make sure that boat has all required safety equipment, like life preservers and fire extinguishers.

The boaters we talked with told us they plan to do their part.

"It's always crowded out there, but especially on holiday weekends," said Erik Mineishi. "So I try to stay away from everyone."

Powell and his fellow Deputy John Potter are also reminding boaters that the new California Boater Safety Card is already required for operators 25 years of age or under.

Over the next several years, the card, and required safety test, will be required of boat operators of all ages.

WATCH: ABC7's Laura Anthony rides along with Contra Costa County Sheriff's Marine Patrol for July 4th festivities

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