The applicant shall clearly state the name of the source from which the diversion or use of water is proposed. Source refers not to the origin of the water, but to the stream, spring, or body of water from which the proposed diversion will be made. If the source has no name, it may be designated as an unnamed watercourse or an unnamed spring. If the source is a tributary, the next stream into which it flows and the river basin wherein it lies shall be given.
30 Tex. Admin. Code § 295.4