This dataset depicts marine habitats, saltmarsh and wetland within and adjacent to the Derwent River estuary from New Norfolk to Iron Pot. The dataset combines and simplifies data from previous studies undertaken between 1999 and 2008 into a non-overlapping polygon representation (see Lineage). The habitat types depicted in the dataset include Cobble, Reef, Sand, Silt, Rock, Aquatic Macrophytes, Seagrass, Macrocystis pyrifera, Wetland and Saltmarsh vegetation communities. The dataset is intended to be used for education, awareness raising and to assist in planning and management.

The atlas combines data collected between 1999 and 2008 into non-overlapping polygons. Polygons have been overlayed and all overlaps and self intersections removed. Gaps less than 10 sq metres have been cleaned from the dataset were they are anomalies of the processing. Gaps greater than 10 sq m due to discrepancies between dataset boundaries have been retained. Polygon overlays and replacements occurred in the order: 1) cobble, reef, sand & silt habitat mapping from River Derwent: New Norfolk to Iron Pot –1:12,500 Digital Topographic Series, 2007, Tasmanian Aquaculture and Fisheries Institute. Silt, sand, reef and aquatic macrophytes polygons were modified to conform to the Derwent Estuary MHWM from the LIST Hydarea Digital Topographic Series (ANZTA0005000137) due to landfills into the estuary. 2) Unvegetated mud flat, Sand and Rock mapping from LIST Hydarea Digital Topographic Series (ANZTA0005000137), ILS. 3) Shipwreck, Aquatic Macrophytes (modified as described above) and seagrass habitat mapping from River Derwent: New Norfolk to Iron Pot –1:12,500 Digital Topographic Series, 2007, Tasmanian Aquaculture and Fisheries Institute. 4) Macrocystis pyrifera communities from A Survey of the M. pyrifera (L.) C. Agardh Stocks on the East Coast of Tasmania, 1999 (ANZTA0023000006), Seacare P/L. 5) Saltmarsh and wetland data (mapped using 1:24000 orthoimages flown in 2001 ) were extracted from the following datasets: Vegetation Communities along the Clarence Municipality section of the Derwent Estuary (ANZTA0039000002) 2008, Derwent Estuary Program; Vegetation of the Upper Derwent Estuary Wetlands (ANZTA0039000007) 2008, Derwent Estuary Program; and Vegetation (ANZTA0020000019) 2006, NRM South Coastal Values Project, Department of Environment, Parks, Heritage and the Arts. The orthoimages used to map the wetlands and saltmarshes do not conform to the Derwent Estuary MHWM from the LIST Hydarea Digital Topographic Series (ANZTA0005000137).

Position Accuracy: The positional accuracy of this dataset depends upon the positional accuracy of the datasets used in its compilation. Based on the least accurate dataset not less that 90% of well defined data is within 17.5m of true position and each record is attributed with its source dataset if further information is required. Attribute Accuracy: The attribute accuracy of this dataset depends upon the attribute accuracy of the datasets used in its compilation. Each record is attributed with its source dataset if further information is required and the source dataset reliability, date and identifier attributes are included where available. Logical Consistency: The dataset has been checked for general topological errors with MapInfo 9.0. All overlaps and self intersections have been removed. Gaps less than 10 sq metres have been cleaned from the dataset were they are anomalies of the process. Gaps greater than 10 sq m due to discrepancies between dataset boundaries have been retained. Completeness: The layer is complete for the Derwent Estuary to MHWM, excluding vegetated land. It is not complete for the Jordan River Estuary that joins the Derwent. Saltmarsh and wetland mapping within 100m of the Derwent Estuary is complete. Individual metadata reports for listed data sets should be referred to for further information.