Due to the lack of stream guaging stations, a peak flow simulation based on physical and meteorological parameters was established for the area along the proposed Mackenzie Valley Highway between Fort Good Hope and the Dempster Highway.Calculations based on snowmelt and rain-on-snow runoff were developed, as it was found that the snowmelt of May or early June gave the yearly spring peak discharge.Due to the gap in existing flow data, a unit hydrograph method was developed to generate additional yearly spring peak discharges. Altogether, hydrographs from four gauged watersheds of similar physical conditions with size ranging from 250 to 8 200 mi2 (648 to 21 240 km2) were used. In total, 46 yearly peak flows were generated.A regression equation of peak discharge computation was derived, using different hydrological and meteorological parameters. It was found that the most significant factors were the drainage basin area, the lake areas in the drainage basin, the water equivalent of the snow on the ground prior to melt, the rainfall in the period close to peak discharges, and the duration of snowmelt.The simulation was calibrated for drainage basins between 100 and 10 000 mi2 (250 to 25 000 km2).