||The Estuarine Tidal Riverine Open Water Subsystem includes tidal freshwater areas with a salinity of <0.5 and a depth of greater
than 4 meters at MLLW.
The Estuarine Tidal Riverine Open Water Subsystem is the most upstream portion of the estuary
and subject to river and watershed influences, including high nutrient and sediment loads and low salinity. Similar to the
Estuarine Open Water Subsystem, physical impact from waves and surface currents is reduced interaction at depth. This zone
may be the site of the upper limit of the salt wedge and of a turbidity maximum zone, important as feeding and aggregation
sites for plankton and benthic species. This zone is also potentially subject to high organic loading and formation of hypoxic
waters. Primary production is often low, due to high turbidity and deep, dimly lighted water columns, especially in the river
channel. For this reason, the Tidal Riverine Open Water Subsystem may be heterotrophic with net negative metabolic rates.