Because it begins as freshwater in its northern reaches and flows into tidal salt water at Long Island Sound, Farm River is by definition an estuary.

[3] The USGS identifies the river's headwaters as an area below the southeast flank of Pistapaug Mountain in the town of North Branford.

[1] The Friends of the Farm River Estuary name the river's source as Pistapaug Pond, a reservoir straddling the town lines of Wallingford, Durham and North Branford, below the west flank of Pistapaug Mountain.

[4] From its northern reaches, the river flows southward into the town of East Haven where it becomes the dividing line between East Haven and Branford.

The name Farm River was officially decided upon in 1968.