Chichester Harbour is an Area of Outstanding Natural Beauty. The harbour is of national and international importance for nature conservation. It is a Site of Special Scientific Interest, a wetland of international importance, a Special Protection Area for wild birds and a Special Area of Conservation. The harbour is of particular importance for wintering wildfowl and waders of which five species reach numbers which are internationally important.
There are a number of habitats including a large area of salt marsh habitat and mudflats which are exposed at low tide. These areas are particularly important for wintering birds. Chichester Harbour is a designated Bass Nursery Area.