Image zoom infers that two more targets were bolted at abutting expansion joints on the left spillway sidewall. These optical targets have concise black and white aligned stripes on two panels. Each panel is bolted to one side of the expansion joint seam. Any differential movement (i.e. expansion) of the joint would cause the stripes to shift with respect to each other. Using a good zoom camera, the shift may be detected & measured from a safe distance away from the wall. The clearing of the foundation of the removed electrical tower shows the clearing extended to the sidewall. This clearing provides a good "straight on" view to the targets. Prior to clearing the hillside soil base was blocking a straight view to the uppermost target.
The green drain piping installed into the original broken section of the sidewall drain shows waterflow from the output.
Two "slippage detection" targets bolted to backside of left spillway sidewall. Cleared foundation area of removed electrical tower allows view access of the optical targets. note: Green drain pipe waterflow - working drains.
"Slippage detection" optical target bolted to inside of spillway chute sidewall. This is at a damaged section of the upper spillway where downslope movement of the left sidewall and adjacent main slab occurred before repairs.
