This habitat occurs in quiet areas back from stream channels, currents and wave action where silt or a mixture of silt and sand settles and where there is freshwater influence. The substratum is often very soft and typically anoxic.
The bulrush Scirpus maritimus, Triglochin maritimum and the sedge Carex lyngbyei are the most commonly occurring marsh species in this habitat.
The bulrush Scirpus americanus occurs where there is a relatively high sand content.
Nooksack River Delta, Skagit Bay, Port Susan Bay, Oakland Bay, Quilcene Bay, Nemah River, Bear River.
Kunze, 1984; Ewing, 1983 and 1982; Kunze and Cornelius, 1982; Disraeli, 1977; Jefferson, 1975.