Skipanon clamshell campaign has a dated survey baseline

The September chart states its own depth reference

Portland District's 2 September survey shows the entrance and the bend towards Warrenton. Its notes give soundings in feet below Mean Lower Low Water and describe the existing project as maintained at 16 ft based on user needs. The chart represents conditions on its survey date. Its register supplies the PDF, XYZ data and shape files for the same survey.

The scow cycle affects digging time

Clamshell excavation transfers material into a scow, so continuous digging depends on loading capacity, scow availability and the permitted placement journey. The current plant listing establishes the named equipment; it gives no cycle time or completed quantity. For campaign control, the daily record should link dredge position and loading hours to scow departures, returns and placement records. That makes a transport interruption visible alongside any limitation at the digging face.