(Springfield, OR)  --  Boaters are being warned about the water flow at the McKenzie River.  The Lane County Sheriff Office says two trees are lying across the river about a mile upstream of Bellinger Landing and could create a problem with the river's flow.  The sheriff's office says drift boats are currently able to pass if they stay river right, however if the trees shift the area could become impassable.  The issues has been reported to the Oregon State Marine Board.