N.C. Gen. Stat. § 77-3
The board of county commissioners may appoint commissioners to examine and lay off the rivers and creeks in their county; and where the stream is a boundary between two counties, may lay off the same on their side; in doing so they shall allow three fourths for the owners of the streams for erecting slopes, dams and stands; and one-fourth part, including the deepest part, they shall leave open for the passage of fish, marking and designating the same in the best manner they can; and if mills are built across such stream, and slopes may be necessary, the commissioners shall lay off such slopes, and determine the length of time they shall be kept open; and such commissioners shall return to their respective boards of county commissioners a plan of such slopes, dams, and other parts of streams viewed and surveyed.
N.C. Gen. Stat. § 77-3