The Saint-Maurice River is one of the main tributaries of the St. Lawrence River, after the Ottawa and the Saguenay Rivers and drains an area of 42,735 km. It touches the Lake Saint John watershed to the north; the Nottaway River watershed, a major tributary of James Bay, to the northwest; and the southwestern tributaries of the Ottawa River. The …The Saint-Maurice River is one of the main tributaries of the St. Lawrence River, after the Ottawa and the Saguenay Rivers and drains an area of 42,735 km. It touches the Lake Saint John watershed to the north; the Nottaway River watershed, a major tributary of James Bay, to the northwest; and the southwestern tributaries of the Ottawa River. The Saint-Maurice River is located on the north shore of the St. Lawrence River in Quebec, Canada.