Go to the first waypoint and find the following information.
Prison was originally opened 183X.
At least 11,7Y4 soldiers were held at this facility.
Input X and Y into the following waypoint.
N 38° 52.9Y5
W 90° 11.X10
Go to this waypoint and count the number of large concrete piers left from the old dam.
Email me the answer - don't post the answer here - even if encrypted.
Also at this location:
View of Clark Bridge
Old Dam Structure
Walking and Biking Paths
Large Parking Lot
Boat Launch Ramp (no dock)