The north side of Snow Mountain drains into Indian Stream, then into Chain of Ponds, the North Branch of the Dead River, Flagstaff Lake, the Dead River, the Kennebec River, and into the Gulf of Maine. The southeast side of Snow Mountain drains into Little Alder Stream, then into Alder Stream, and the North Branch of the Dead River. The north side of Snow Mountain drains into Big Island Pond, then into the Kennebago River, and the Androscoggin River, which drains into Merrymeeting Bay, the estuary of the Kennebec River.