A boom support arm that includes: a frame having a coupling positioned above a high water level; a support arm having a first end and a second end, the first end being pivotally coupled to the coupling on the frame for pivotal movement of the second end of the support arm between the high water level and a low water level; and a flotation assembly connected to the second end of the support arm. Use of the boom support arm in combination with a floating boom system for inhibiting damage to a fixed terminus of the floating boom system is also disclosed.