East Branch Union River

Left: Bog River
Right: Middle Branch Union River

East Branch Union River
Country	United States
Basin features
Main source	Maine
River mouth	Union River 32 feet (10 m) 44°43′53″N 68°22′52″W / 44.7315°N 68.3810°W / 44.7315; -68.3810Coordinates: 44°43′53″N 68°22′52″W / 44.7315°N 68.3810°W / 44.7315; -68.3810
Tributaries	Left: Bog River Right: Middle Branch Union River
Physical characteristics
Length	21.6 miles (34.8 km)

The East Branch Union River is a 21.6-mile-long (34.8 km) river in Hancock County, Maine. From the outflow of Rocky Pond (44°47′33″N 68°08′34″W / 44.7924°N 68.1427°W / 44.7924; -68.1427 (West Branch Union River source)) in Maine Township 22 M D, the river runs 5.3 miles (8.5 km) southwest to Spectacle Pond in Osborn. From the pond's outlet, the river runs 13.0 miles (20.9 km) northwest, southwest, west and southwest to Graham Lake, where it joins the West Branch to form the Union River. The lower section of the East Branch forms the border between Mariaville and Waltham.