S.C. Code Ann. § 48-11-30

The area embraced in a watershed conservation district must be contiguous, must lie within a well-defined watershed, and must be situated within one or more soil and water conservation districts. The area may not include lands located within the boundary of an incorporated municipality, unless approved by its governing body, or another watershed conservation district. The boundary of each watershed conservation district in existence on the effective date of this chapter, as amended, is not affected unless otherwise provided in this chapter.