As a supplement to a 1975 report, titled "Floodflow Characteristics at Proposed Bridge Site on Mohawk River, Whitesboro, New York," by Bernard Dunn (U.S. Geological. Survey open-file report), in which the hydraulic effects of two alternative highway plans during a large-magnitude flood were evaluated, a hydraulic analysis was made for a third highway plan. The two plans evaluated in the original report had been found by the State Department of Transportation to be infeasible. A design-flood discharge of 18,200 cubic feet per second was used in the new evaluation, as in the original report. The recurrence interval of that flood is approximately 100 years. The corresponding peak flood stage at the proposed bridge site was determined by the New York State Department of Transportation to be 411.8 feet.
During the design flood, the new proposed alternative would cause a 0.1-foot increase in water-surface elevation from the bridge to the approach section; 1,300 cubic feet per second would overflow the road north of the bridge and 6,800 cubic feet per second south of it. Discharge through the bridge would be 10,100 cubic feet per second.
