The plain at first was drained by the Cloquet River, which then ran west to the Mississippi River. By the process of stream piracy, the smaller Saint Louis River, which runs to Lake Superior, captured the Cloquet River and most of its drainage basin. This left behind the East Savanna River which drains into the Saint Louis River, Lake Superior, the lower Great Lakes, and the Saint Lawrence River, and to the west, the West Savanna River, which is tributary to the Mississippi River.