WellStar Health System is challenging Northside Hospital’s plan to build a $250 million replacement hospital in Cherokee County.

In a Sept. 1 letter to the state Department of Community Health, the health system said Northside has not proved it should be exempt from Georgia’s certificate-of-need process for its proposed Canton facility. The process requires hospitals to get state approval for major construction and expansion projects.

Northside officials say they are exempt from CON review because the new hospital would be less than three miles from the existing facility, which was built in 1962. It also wouldn’t offer new or expanded health services.

“WellStar believes that Northside Cherokee Hospital has failed to provide sufficient information and documentation to support its request for an exemption,” spokesman Keith Bowermaster said in a statement.

WellStar has some health care facilities, such as physicians practices, in Cherokee County but no hospital.

Plans for the new hospital near I-575 call for 84 beds, a women’s center, a medical office building and a cancer center. It would open in March 2015 if approved.

“We will vigorously defend against the opposition on this project to make this vision a reality for the residents of Cherokee County,” Northside Hospital-Cherokee CEO Billy Hayes said in a statement.