In 2005 during heavy storms, there was great concern for its stability as the area directly below the dam severely flooded.
Low areas in many of the Island's 60 vineyards flooded, and some grapes were waterlogged.
Power was turned off section by section as areas flooded, but not until trains in the area had cleared.
"I think the area would have flooded even without the work in progress but the question is just how much."
In Spring of 2013, some areas which were drought strikend flooded.
Before Sacramento's extensive levee system was in place, the area flooded quite regularly.
Some low-lying areas have flooded during storms, and the city is trying to improve drainage.
Some areas that initially seemed to suffer little from the storm found themselves flooded by rapidly rising water on August 30.
The site has experienced rapid changes in water levels during its history, and contains the trunks of birch trees which died when the area flooded.
The ground was noticeably lower than at the cliff's edge, so the area probably flooded during storms.