My hometown is getting slammed by Florence. The river is expected to crest at 62' https://water.weather.gov/ahps2/hydrograph.php?wfo=rah&gage=fayn7 The topo of the area is from 50' to 170-190' Is there correlation between River Levels shown in the link and the MSL or reported ASL numbers on the topo maps?
You need to look at the datum elevation (19 ft msl) which is stage 0.0. If flood is 62 ft above stage, then the elevation of the water will be 19+62 = 81 msl at that particular station.