The East Gallatin River flows 42 miles (68 km) in a northwesterly direction through the Gallatin valley, Gallatin County
. Rising from the confluence of Rocky Creek and several other small streams, the East Gallatin begins about one mile (1.6 km) east of downtown Bozeman
, Montana. The river joins the main stem of the Gallatin River 2.3 miles (3.7 km) north of Manhattan
The East Gallatin river is a popular trout fishing stream and holds good populations of Rainbow and Brown trout as well as Mountain Whitefish
. Access is limited to country road crossings and two public assess sites maintained by the Montana Fish, Wildlife and Parks department.