Wis. Stat. § 236.025: Ordinary high water marks.

(1) For purposes of ss. 236.15 (1) (ag) and (d) and 236.20 (2) (g), a professional land surveyor may do any of the following:

(a) Incorporate into a map, plat, or survey an ordinary high water mark that has been determined by the department of natural resources or otherwise determined pursuant to law.

(b) Approximate the ordinary high water mark and incorporate that mark into a map, plat, or survey.

(2) For purposes of sub. (1) (b), the location of the approximate ordinary high water mark shall be the point on the bank of a navigable stream or on the shore of a lake up to which the presence and action of surface water is so continuous as to leave a distinctive mark by erosion, destruction of terrestrial vegetation, or other easily recognized characteristics. If the approximate location of the ordinary high water mark is difficult to determine, a professional land surveyor may consider other points on the bank or shore for purposes of approximating the location of the ordinary high water mark.

(3) For purposes of this section, a map, plat, or survey that shows an approximate ordinary high water mark shall state on its face that the mark is shown for reference only.