For the purposes of this chapter, unless the context otherwise indicates:
1. "Free-flowing" shall mean existing or flowing in a natural condition without impoundment, diversion, straightening, or other modification of the waterway.
2. "Little Missouri River" means the river commencing at the North Dakota-South Dakota state border and terminating at its juncture with Lake Sakakawea, with such juncture defined as the bridge crossing of state highway twenty-two in section thirty-four, range ninety-five west, township one hundred forty-eight north, with boundaries established as the natural channels of the river to the low water mark.