composed primarily of fresh water estuarine coastal surface layer estuarine tidal riverine coastal surface layer envoCmecs This class aligns to the Coastal and Marine Ecological Classification Standard (CMECS). In ENVO, we may adapt the definition for consistency, but the semantics (meaning) of the term should be unaffected. Please consult the CMECS catalogue (https://cmecscatalog.org/) for authoritative and semantically unconstrained definitions. CMECS:603 A layer of fresh estuarine water which extends a few centimeters from the surface of the water column towards the estuary bed and from the land-water interface to a fiat boundary where the estuary bed below the water column reaches a depth of 4 meters. What causes this freshwater layer to be "tidal" is not clearly specified in the current CMECS definition. https://cmecscatalog.org/cmecs/classification/unit/603.html envoMarine