Plesetsky District
The river basin of the Kena covers a vast area in the western part of Plesetsky District and some minor areas of Onezhsky District. The main tributary of the Lake Kenozero is the Pocha, which, in turn, flows out of Lake Pochozero. The main tributary of the Lake Pochozero is the Undosha. The source of the Undosha is the Lake Undozero, one of the biggest lakes of the region, and a major right tributary is the Toksha.