The Calvert County commissioners approved regulations Tuesday limiting "big-box" retail stores to 120,000 square feet in Prince Frederick and 75,000 square feet in Solomons and the county's designated minor town centers.

Stores 75,000 square feet or more must include smaller adjacent stores -- called co-located units in the new rules -- that account for at least 20 percent of the total retail space. That means the entire shopping site, with the co-located space, could reach 144,000 square feet in Prince Frederick and 90,000 square feet in the smaller town centers.

The limitations will hinder plans to build a 145,000-square-foot Wal-Mart in Dunkirk and to expand the Prince Frederick Wal-Mart to 187,000 square feet, said Mia Masten, regional community affairs manager for the retail giant.

The Prince Frederick limitations passed 3 to 2, with commissioners President David F. Hale (R-Owings) and Commissioner Wilson H. Parran (D-At Large) opposed. Size limits could cause companies to build two smaller stores with the same consequences as one large big-box store, they said.

"You may limit the size of the big box," Parran said, "but you may end up getting two big boxes."

Big-box stores in Solomons, Dunkirk and Lusby will be limited to 90,000 square feet, including co-located units. Hale voted against the limits in Dunkirk.

Commissioner Susan Shaw (R-Huntingtown) said Dunkirk -- a northern entry point to the county -- could not accommodate the traffic generated by large big-box stores.

"We don't have the infrastructure, and we don't have any way to get it," Shaw said. "We absolutely cannot have gridlock -- when we do that, we kill this county's economy."

The commissioners limited stores in St. Leonard and Huntingtown to 25,000 square feet. In rural commercial districts, the total of all buildings in a small commercial center cannot exceed 25,000 square feet.

Commissioner Linda L. Kelley (R-At Large) said the limits would not keep big-box stores out of the county, especially with the high limit in Prince Frederick. Home Depot stores, for example, usually cover 107,000 square feet, she said.

The 120,000-square-foot restriction "covers the kinds of businesses we wanted to attract here," Parran said.

Measures adopted by the commissioners also require stores bigger than 75,000 square feet to have maintenance agreements and to meet appearance standards. Any outdoor sales areas must be specifically identified and must include fencing and landscaping. They cannot be operated in parking lots or impede pedestrian walkways.

Also, the site owner must maintain the building's exterior and help mitigate additional traffic congestion by adding lanes or signal lights to adjacent roads.

As they voted Tuesday, the commissioners noted the hundreds of e-mails, letters and statements they have received from the public on the big-box issue.

"We have had a tremendous amount of public input," Kelley said. "The public has been divided on the issue, almost right down the middle."

Shaw said she found much rampant public misinformation about the effects of big-box stores on the county's economy.

The revenue received by such large retailers does not filter back to the community, she said, but rather goes to each store's home office.

Locally based businesses, on the other hand, spend their receipts in the community, and those funds cycle through the local economy an average of seven times, Shaw said.

In the end, the commissioners said they wanted stores that would serve the county, but not necessarily the region beyond Calvert. The store-size limitations, they said, were set to focus retail operations on consumers within the county.

"It is not unlike inviting an 800-pound gorilla into your living room to get a store that size in the county," Kelley said of the much larger superstores that will be prohibited under the new regulations.