S.C. Code § 55-3-90
Navigable waterways, which are available for use under the public trust doctrine, may be used for the landing, docking, and takeoff of seaplanes in accordance with this provision. This section does not authorize the use of seaplanes in a manner or location which would violate the property rights of another person.
During the landing, docking, and takeoff of a seaplane, its pilot shall comply with all applicable federal and state laws and aeronautical rules.
Seaplane takeoff, landing, and water operations must be done safely and in a manner which does not endanger other persons, watercraft, and property.
A seaplane shall not land, dock, or take off on a waterway in a manner that would violate applicable laws, ordinances, and rules if done by a motorized watercraft, except that a seaplane is not required to comply with a statewide speed limit for watercraft while landing and taking off, if a higher speed is necessary for safe operation and is not in conflict with any other restrictions applicable to watercraft.
In no event shall the landing, docking, or takeoff of seaplanes be approved if the landing, docking, or takeoff would pose unreasonable risks to public health, safety, or property as determined by the division.
S.C. Code § 55-3-90