The northeast side of Pico Peak drains into Kent Brook, thence into the Ottauquechee River, the Connecticut River, and into Long Island Sound in Connecticut. The southeast side of Pico drains into Roaring Brook, and thence into the Ottauquechee. The northwest side of Pico drains into Mendon Brook, thence into East Creek, Otter Creek, and Lake Champlain, which drains via the Saint Lawrence River into the Gulf of St. Lawrence in Quebec, Canada. The southwest side of Pico drains into Brewer's Brook, and thence into Mendon Brook.