The bridge was under construction during the 1993 flood. The bridge was above the waterline during the flood, so construction continued during the food. The construction offices were flooded out, so a temporary office was set up in a old semi-trailer. At the peak of the food, the old bridge, the MacArthur, was the only bridge open between the Quad Cities and Saint Louis. The MacArthur was finally shut down for 4 days, not because of issues with the bridge, but from concerns that the vibrations of the bridge would weaken the nearby levees.
The Great River Bridge is interesting from several vantage points. First, it is a single tower cable stay bridge, unusual for such a large river crossing. Second, it is asymmetrical. That is, the suspended deck on one side of the tower is shorter than the deck on the other side of the tower. Third, it has an unequal number of stay cables. There are 13 pair on the east side, 14 pair on the west side. Fourth, the suspended deck does not fully cross the main river channel. Rather, the east side has a steel girder causeway leading up to the main bridge that spans a third of the channel. The main tower is about in the center of the river. Finally, the bridge has 8 lifter cables to ensure that it stays level. Those cables run from the main tower to the deck on the east side, connecting to the deck east of the first short pier. These cables lift the deck east of the sort pier, which puts downward force on the deck in the suspended span. This helps prevent some of the hump that would occur as temperatures change, and materials expand and contract.
The main tower is reported to be 370 from bedrock to the top. I have not found a number for how high the tower is above the waterline. I estimate that it is 300 feet based on measuring photographs.