The commission expects to discuss an agreement on the property at a meeting Tuesday, Commissioner Harold Brooker said.
Prater's Mill is in northern Whitfield County near Varnell and is on the National Register of Historic Places. It's home to Prater's Mill Country Fair, an annual festival that attracts thousands of visitors each year.
Judy Alderman, founder of the Prater's Mill Foundation, had leased the property since 1971, but that lease expired on Dec. 31. She said last fall that she wasn't sure what would happen to the property.
"We have always wanted it to be a public history site, owned by the public," she said.
Mr. Brooker said the county got involved "when we found out the lease was running out."
He said he's negotiated with the property owners -- Ken Boring and the estate of the late Jim Boring -- for the past six to eight months. Hopes are that about 18 acres around the mill site will be donated as a county park, Mr. Brooker said.
"We'll probably turn around and lease it back to the Prater's Mill Foundation and let them continue doing what they're doing," he said.
Ms. Alderman said the foundation is a nonprofit organization and has more than 100 volunteers.
Calls to Ken Boring were not returned.
Commission Chairman Mike Babb said the county would have an arrangement with Prater's Mill similar to the one it has with the Tunnel Hill Historical Foundation, which oversees the historic Clisby Austin House and its 80-acre property. He said the county owns the Clisby Austin property, but the historical foundation takes care of it.
Mr. Brooker said, under county ownership, Prater's Mill would remain open to the public.
The county would insure the property under its blanket policy, said Mr. Brooker, so the foundation has "more time and money to put into the mill itself."
The Prater's Mill Country Fair takes place one weekend in the fall, but Mr. Brooker said he'd like to see the fair put on twice a year, like it was in the past.
He said Prater's Mill "builds tourism" and the fair brings a lot of revenue to the area.