Tex. Natural Resources Code § 21.012: SURVEYS ON NAVIGABLE STREAMS.

(a) If the circumstances of the lines previously surveyed under the law will permit, land surveyed for individuals, lying on a navigable stream, shall front one-half of the square on the stream with the line running at right angles with the general course of the stream.

(b) A navigable stream may not be crossed by the lines of a survey.

Acts 1977, 65th Leg., p. 2355, ch. 871, art. I, Sec. 1, eff. Sept. 1, 1977.