Authorities in Douglas County are warning the public about counterfeit money circulating in the area - mostly $20 bills, but also a few $10 bills.

Even child entrepreneurs have not been immune. A man reportedly asked a young girl for change from her Kool-Aid stand Sunday in Lake Nebagamon and gave her counterfeit money in exchange, according to Douglas County Sheriff's Office records.

Newsletter signup for email alerts

Superior police Det. Chris Moe said 23 counterfeit bills have been reported in the city since February, including three over the weekend and a new report Monday morning.

Moe said merchants should be alert when accepting larger bills, and encouraged them to use marking pens.

"If they think it is a suspicious bill or a known counterfeit bill, the business does not have to take it and can ask for alternate payment," Moe said. "They also do not have to give it back to the presenter if it is a known counterfeit bill, and they can call us when this happens."

The number to call is 911.

Tracing a fake bill's path to a suspect can be challenging.

"They are difficult cases to work because money can change hands so many times a day," Moe said. "Unless people know what to look for or are alert to this, they may not even realize they have a counterfeit bill."

Find tips on spotting counterfeit money here.