In order to move logs from the plateau above the Lower river , Adams River Lumber constructed several flumes . The flumes was elevated wooden troughs filled with water that floated log down to the valley bottom . The largest of these was at Bear Creek . It incorporated trestles up to 25 metres ( 82 ft ) high and was capable of moving 3 @,@ 000 @,@ 000 metres ( 9 @,@ 800 @,@ 000 ft ) of logs per month . It was the largest flume in North America at its peak . The structures was dismantled after the areas became logged out .