Natural channel
Defined in 1 dictionary — Black's (1910)
Black's Law Dictionary
Henry Campbell Black, M.A. · 1910
The channel of a stream as determined by the natural conformation of the country through which it flows ; that is, the bed over which the waters of the stream flow when not in any manner diverted or interfered with by man. See Larrabee v. Cloverdale, 131 Cal. 96, 63 Pac. 143.
Defined under Channel in Black's Law Dictionary.