The campaign of Montgomery county executive candidate Nancy Floreen, who is running as an independent, returned $18,000 in contributions that it could not determine were legally given. (Sarah L. Voisin/The Washington Post)

Montgomery County executive candidate Nancy Floreen has returned $18,000 in campaign contributions after a county resident filed a complaint alleging that the donations were improper.

Floreen’s campaign manager, Rich Parsons, said the campaign scrutinized the $57,000 in contributions listed in the Sept. 15 complaint by Gaithersburg resident Kenneth Myers, and found that five of them, totaling $24,000, could have been made by entities that are owned by the same individuals. Under state law, contributions are limited to $6,000 from a person or group. But the law also puts the onus on complying with the limits on the contributor, not the campaign.

Parsons said four contributions were returned: $3,000 from Park Potomac Condominium (Venture) 1 LLC; $6,000 from Silver Spring Metro Center LLLP; $3,000 from Park Potomac Condominium (Venture) 2 LLC; and $6,000 from SSMC III Limited Partnership.

All four donors, along with SSMC IV, LP, which gave $6,000, listed their addresses as 12435 Park Potomac Ave., Suite 200, in Potomac. That is the same address as Foulger-Pratt, the real estate development firm that was the general contractor for the troubled Silver Spring Transit Center and is involved in many other major projects in the county.

A call to Foulger-Pratt was not immediately returned Monday.

“The campaign obviously did not know the complex internal corporate ownership structures of these private entities, which are not publicly available, and would never have accepted any contribution that was potentially over the limit,” Parsons said in an email.

He said the campaign is “fully cooperating with the State Board of Elections on this and expect this matter to be closed soon.”

Jared DeMarinis, the state board’s director of candidacy and campaign finance, said the matter is under review.

Floreen, a longtime county council member, dropped her Democratic Party affiliation this summer to seek Montgomery’s top political office as an independent. She is competing against Democratic nominee Marc Elrich, a council colleague; and Republican Robin Ficker. Both Elrich and Ficker are participating in the county’s public finance system, which requires them to raise small donations from county residents and prohibits contributions from corporations or unions.