Farmington is drained by the Ela River, Mad River and Cochecho River. Baxter Lake, on the southeast border, is the largest water body in the town. Part of the Blue Hills Range, foothills of the White Mountains, is in the southwest. The highest point in Farmington is Blue Job Mountain, at above sea level. Farmington lies almost fully within the Piscataqua River (Coastal) watershed, with the westernmost corner of town located in the Merrimack River watershed.