9c1b3464_WQP_User_Guide__Definition
[Site Type] Estuary [Definition] 
A coastal inlet of the sea or ocean; esp. the mouth of a river, where tide water normally mixes with stream water (modified, Webster). Salinity in estuaries typically ranges from 1 to 25 Practical Salinity Units (psu), as compared oceanic values around 35 psu.
WQP User Guide
Definition