Mich. Comp. Laws § 408.326a

Sec. 6a. Each ski area operator shall, with respect to operation of a ski area, do all of the following: (a) Equip each snow-grooming vehicle and any other authorized vehicle, except a snowmobile, with a flashing or rotating yellow light conspicuously located on the vehicle, and operate the flashing or rotating yellow light while the vehicle is moving on, or in the vicinity of, a ski run. A snowmobile operated in a ski area shall be operated with at least 1 operating white light located on the front of the snowmobile. (b) Mark with a visible sign or other warning device the location of any hydrant or similar fixture or equipment used in snow-making operations located on a ski run, as prescribed by rules promulgated under section 20(3). (c) Mark the top of or entrance to each ski run, slope, and trail to be used by skiers for the purpose of skiing, with an appropriate symbol indicating the relative degree of difficulty of the run, slope, or trail, using a symbols code prescribed by rules promulgated under section 20(3). (d) Mark the top of or entrance to each ski run, slope, and trail which is closed to skiing, with an appropriate symbol indicating that the run, slope, or trail is closed, as prescribed by rules promulgated under section 20(3). (e) Maintain 1 or more trail boards at prominent locations in each ski area displaying that area's network of ski runs, slopes, and trails and the relative degree of difficulty of each ski run, slope, and trail, using the symbols code required under subdivision (c) and containing a key to that code, and indicating which runs, slopes, and trails are open or closed to skiing. (f) Place or cause to be placed, if snow-grooming or snow-making operations are being performed on a ski run, slope, or trail while the run, slope, or trail is open to the public, a conspicuous notice at or near the top of or entrance to the run, slope, or trail indicating that those operations are being performed. (g) Post the duties of skiers and passengers as prescribed in sections 21 and 22 and the duties, obligations, and liabilities of operators as prescribed in this section in and around the ski area in conspicuous places open to the public. (h) Maintain the stability and legibility of all required signs, symbols, and posted notices.