PUEBLO, Colo. -

Memorial Day Weekend is one of the busiest times of year at Lake Pueblo State Park. Park rangers are making sure people are staying safe.

That includes looking out for marijuana users. It's illegal to smoke pot in public places like Lake Pueblo.

"We're enjoying a beautiful lake that we have and weather, good friends," said boater Lionel Montoya.

What could ruin the weekend is seeing red and blue flashing lights.

"Occasionally, we do run into situations where people may be under the influence of marijuana or alcohol,” said Brian Kerrigan, Lake Pueblo State Park Operations Manager.

Park rangers are patrolling the water and the rest of the park for trouble including smoking pot on public property.

"Typically we're looking for a number of different indicators. One could be the odor of marijuana. One could be pupil size. It could be speech patterns,” said Kerrigan.

"Especially with the kids being around, they don't need to be around that stuff,” said park visitor Brian Marquis.

Marquis and his family and friends say they're keeping each other safe on and off the lake.

"If they're going to be driving a boat, don't drink and if they're going to be swimming, make sure that they're not drinking, too,” he said.

"There's a lot of things that can go wrong on a lake and so you always have to have a sober driver and make sure that you're boating responsibly,” said Montoya.

That’s exactly the message park rangers are spreading to everyone. Park rangers say they haven't had any alcohol or marijuana problems so far this weekend.