has part composed primarily of fresh water estuarine coastal upper water column estuarine tidal riverine coastal surface layer estuarine tidal riverine coastal upper water column A layer of fresh estuarine water which extends from the surface of the water column to the pycnocline or mid-depth and from the land-water interface to a fiat boundary where the estuary bed below the water column reaches a depth of 4 meters. "Mid-depth", present in many CMECS classes, is ambiguous and needs refinement. What causes this freshwater layer to be "tidal" is not clearly specified in the current CMECS definition. envoMarine 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:604 https://cmecscatalog.org/cmecs/classification/unit/604.html envoCmecs