The cache owners have only accessed this site via a canoe, during high water. Google Earth shows a low water image with land access, so you MAY be able to get to ground zero by a hike. Beware that there are cliffs to scale down to get to the shore line. You MAY be able to WADE across to the island, swimming is prohibited in the reservoir. Therefore, this is a 4.5 T rating by water and a 3.5 if you hike to it.
You do not need to use any tool to open the container.
[Favorite points always appreciated.].