Peekamoose Mountain stands within the watershed of Rondout Creek, a tributary of the Hudson River, which drains into New York Bay. The east and southeast slopes of Peekamoose Mtn. drain into Rondout Creek. The southwest end of Peekamoose drains into Buttermilk Falls Brook, thence into Rondout Creek. The west side of Peekamoose drains into Bear Hole Brook, thence into Rondout Creek.