Lane County Sheriff's Office Marine Patrol deputies are advising boaters of low water levels at Fern Ridge Reservoir that could present a hazard.  There are several partially exposed tree stumps in the water and potentially many more just under the surface that could be dangerous for boaters and skiers, particularly on northwest section of the reservoir.  Boaters are asked to please use caution when boating in the area.  Marine Patrol deputies are working to place markers near known hazards, but boaters towing skiers, wakeboarders, etc. are encouraged to stay in the deeper sections.