The conclusion of a simple economic analysis is the construction of a foundation for a bridge that would be designed so the bridge is safe from the scour, which would occur in the maximum probable flood. Cases of pier scour alone and abutment scour alone are analyzed assuming reasonable costs of bridge and foundation piles, flood magnitude-frequency relations plotting as straight lines of log-normal paper, the risk of loss during the life of the bridge, and scour prediction relations somewhat verified in the field.