S.C. Code Ann. § 49-19-1480

Any drainage district may construct and maintain any ditch or lateral provided in the Plan of Reclamation across any of the public highways of this State without proceedings for the condemnation of the highway or being liable for damages therefor. Within ten days after a dredge boat or any other excavating machine shall have completed a ditch across any public highway a bridge shall be constructed and maintained over such drainage ditch where it crosses such highway.