The Nelson River is a river of north-central North America, in the Canadian province of Manitoba. The river drains Lake Winnipeg and runs 644 kilometres before it ends in Hudson Bay. Its full length is 2,575 kilometres, it has mean discharge of 2,370 cubic metres per second, and has a drainage basin of 1,072,300 square kilometres, of which 180,000 squ…The Nelson River is a river of north-central North America, in the Canadian province of Manitoba. The river drains Lake Winnipeg and runs 644 kilometres before it ends in Hudson Bay. Its full length is 2,575 kilometres, it has mean discharge of 2,370 cubic metres per second, and has a drainage basin of 1,072,300 square kilometres, of which 180,000 square kilometres is in the United States.