Ok...one more.
http://water.usgs.gov/osw/techniques/bs/BSDMS/Site_Reports/Site58.pdf
I believe this reports shows all the engineering stats on this particular bridge including data on the pilings, information on the bedrock, etc. Much more information than I comprehend.
It indicates there are at least two actual piers in the River channel, says the flow is constricted and fast, discusses scour.
Low chord elevation of 744 minus 60 feet gives a normal water elevation of 684. Piling data says that the pier in the water is near the stream bed elevation of 673. That indicates that the water is about 11 feet deep.