The idea, of course would be to keep it at 660ft long enough to repair the damage if the damage is reparable.
I mean with this leakage, is the dam reparable or is it a goner? What do you think the options are?
I mean if they don’t do something, it sure looks to me that at some point the water customers of Oroville are in danger of getting a lot more water shares than they bargained for.
Right now there is not enough data to infer the risk from this wet area. Earth Fill dams have a normal amount of seepage that is collected in the Drainage Zone chimney. The drawings show a seepage monitoring station at the end of the horizontal Drain Zone where seepage rates may be monitored for changes.
Personally, I don't think there is a structural risk to the dam at this moment. Why? the embankment erosion channels seemed to have developed over a number of years (image overlay & transparency shifting while examining any increases or changes to the erosion channels).
However, any wet area on the back side of the dam is very important to monitor & understand. This is exactly what the prior Dam Inspectors had put into their reports.
There is one avenue I'm still researching - that is, if there is a link to the Palermo Outlet Tunnel OR if there is a link to any type of hillside spring deep in the abutment. An "artificial spring" may be the source as the impervious core has a 50-75ft deep & wide "channel" cut into the hillside rock to act as a "keyed" anchor. If seepage is penetrating into the hillside rock from a grout missed fracture area, the hillside could act as a saturation holding tank (small but a form of a high elevation mini water table). When the reservoir water levels fluctuate below 660 ft, this may allow a backflow of this hillside mini-water table onto the horizontal seam layer 2 top and layer 3 bottom - causing the wet spot & greening to appear.