It is necessary to obtain the elevation of the crest of a weir in a channel without stopping the flow. The water surface elevation upstream of the weir is 96.l ft above mean sea level (MSL). Determine the elevation of the crest of the weir above MSL if the weir is 4. 90 ft wide and discharges 30.9 ft3/ sec. Assume the weir friction loss and the velocity head upstream are negligible.