Now it was necessary to block off the river so all of the water flowed down the diversion channel. The river's average flow was and by June it had fallen to , but by the time work had been completed to a stage that a firm date of 1 July had been selected to attempt the diversion the flow had increased to . Extra bulldozers were allocated to the attempt as the steady increased to and then . If the diversion couldn't be completed before the peak winter flows the project would have incurred a delay of between nine and twelve months. Despite studies that had indicated that the conditions were less than optimum Arnold Downer made the decision to go ahead. Using twelve bulldozers sufficient accumulated earth and rocks was moved at a rate of over twelve hours on 1 July 1954 to successfully divert the river into the diversion channel.