| System | Estuarine |
| Subsystem | Estuarine Coastal |
| Tidal Zone | Estuarine Coastal Intertidal |
| Definition | The substrate in this zone is regularly and periodically exposed and flooded by tides. This zone extends from MLLW to Mean Higher High Water (MHHW). The Coastal Intertidal is exposed regularly to the air by tidal action. |