Beach permeability may range from high to low depending on the mud content of the beach. Wetland greasses frequently rim the estuary at the high water mark. Brackish water conditions are common due freshwater input to the estuary from stream runoff. Exclusively confined to low wave-exposure environments. There is a very sharp transition from high wave exposure on the seaward side of the spit to low wave exposure inside the estuary.
Anthropogenic materials are man-made shorelines that often predominate in urban areas.
Intertidal zone widths are often narrow. Intertidal zone widths are often narrow due to the vertical nature of most structures. Strong tidal currents that occur in channels may be capable of transporting large sediment and often there are unique biological communities are associated with these features. Oblique aerial photo of Nitinat Narrows at the entrance to Nitinat Lake on the Strait of Juan de Fuca.