Carrie Marriott said she and the parents of another child operating the stand in Bethesda were fined for allegedly ignoring warnings to shut down the stand before the county inspector forced them to shut it down, WUSA-TV, Washington, reported Friday.
"This gentleman from the county is now telling us because we don't have a vendors license, the kids won't be allowed to sell their lemonade," Carrie Marriott said.
She said the children were attempting to raise money for a pediatric cancer charity.
Jennifer Hughes, the director of permitting for Montgomery County, said lemonade stands are technically illegal in the county, but the rules are not usually enforced for small operations. However, she said the stand operated by the children was unusually large.
Hughes said other vendors in the area were also warned for operating too close to the US Open due to traffic and safety concerns.