The Fort River is a river in Western Massachusetts and is a tributary of the Connecticut River and runs through the towns of, Amherst, Massachusetts, and ends in Hadley, Massachusetts.

The Fort technically begins as Adams Brook which begins at a pond near Atkin's Reservoir in Shutesbury, Massachusetts (however the ponds aren't part of the reservoir), and flows south-west ward until it reaches the spot where Amythest Brook flows into it, where it becomes the "Fort River." Although it has no dams or man-made structures on the river, some of the Fort's tributaries have reservoirs.

The Fort River has a wide variety of wildlife due to it being the longest free-flowing tributary (having no dams or other man made changes made to the rivers shape or flow) of the Connecticut River. Because of this there is a lot of wildlife making it one of the 3 most diverse rivers in the state. Mussels, Eastern Pearlfish, Sea Lampreys, and American Eel's.

• River resource article