S.C. Code Ann. § 31-3-380

As soon as possible after the creation of an authority, the commissioners shall organize for the transaction of business by choosing from among their number a chairman and a vice chairman and by adopting bylaws and rules and regulations suitable to the purposes of this chapter and Chapter 11. Three commissioners constitute a quorum for the purpose of organizing the authority and conducting the business of it. However, four commissioners constitute a quorum when exercising jurisdiction in the extraterritorial area. The commissioners shall select and appoint such officers and employees, including engineering, architectural, and legal assistants, as they may require for the performance of their duties and shall prescribe the duties and compensation of each officer and employee.