The boundary where fresh water feeds into salt water is called a(n)

Estuary is a partly enclosed coastal body of water by which river water is mixed with seawater. In a broad sense, the estuarine setting is defined by salinity boundaries instead of geographic boundaries. The word estuary is derived from the Latin words aestus (“the tide”) and aestuo (“boil”), signifying the effect produced when tidal flow and river flow meet.

well we can't tell you because we cant see the time give a screen shot or something.