29 CFR §1917.126

1. (a)This section applies to temporary installations or temporary operations near a river bank.
2. (b)Where working surfaces at river banks slope so steeply that an employee could slip or fall into the water, the outer perimeter of the working surface shall be protected by posting or other portable protection such as roping off. In these situations, employees must wear a personal flotation device meeting the requirements of § 1917.95(b).