This dataset is part of the assessment and mapping of foreshore values, condition and pressure in the North and Cradle Coast Natural Resource Management (NRM) Regions of Tasmania. The 13 line maps produced in this study are intended to be used as a tool to assist managers and stakeholders in the identification of management issues with regards to foreshore planning, development, and natural resources. Assessment of the foreshore is based on the division of the mean high water mark into 100 m line segments. Using an assessment framework, each foreshore segment is assigned a score for a series of environmental stressors and values. Segments are colour coded based on their score to reflect their values and the differing levels of risk associated with each stressor This digital line map is a representation of the risk to the intertidal zone in regard to toxicants in the North and Cradle Coast NRM regions and is derived from an assessment of pressure and vulnerability. An explanatory report is available from the data custodian and from the Aquenal website which provides detailed methods and further explanation of the dataset.

The line map of the mean high water mark (MHWM) derived from the LIST 1:25,000 Hydrography layer (supplied 2009) forms the basis of all mapping and is used to represent the intertidal zone. The entire coastline in the North and Cradle Coast NRM Regions, including islands and national parks, is divided into 100 m line segments of which there are over 48,100 in total. Each segment is assigned a unique identifier and attributed with data relevant to each indicator from a variety of sources. Each foreshore segment is assigned a score from 1 to 5 based on an assessment framework. A score of 1 represents negligible risk with regard to toxicants, whilst a score of 5 represents extreme risk. Datasets used to support the assessment are Planning Schemes (ANZTA0002000065), Marine Leases (ANZTA0019000003), Tasmanian Watercourse (ANZTA0005000037) and Mining Lease Database (ANZTA0009000010). Additional data were sourced from the National Pollution Inventory, Australian Land Use and Management, Tasmania Parks and Wildlife Service, local councils, DPIPWE Marine Structures Assessment Project, DPIPWE WWTP locations and discharge, DPIPWE L2 output, MAST, TasPorts, CFEV, Royal Yacht Club of Tasmania, National Tidal Centre and interpretation of orthorectified aerial images. Further information on the source data and processing steps is presented in the project report listed under Data Usage and Contributors.

Position Accuracy: The line map of the mean high water mark used to represent the intertidal zone is taken from the LIST Hydrographic layer. Shorelines formed by artificial features are a compilation of - 1:25 000 Digital Data - Photogrammetric has the following accuracy: Horizontal: Not less than 90% of well defined detail is within 12.5 metres of true. 1:5 000 Digital Data - Photogrammetric data has the following accuracy: Horizontal: Not less than 90% of well defined data is within 2.5 metres of true. 1:25 000 Digital Data - Scanned and on screen digitising has the following accuracy: Horizontal: Not less than 90% of well defined data is within 17.5 metres of true position. 1:5 000 Digital Data - Scanned and on screen digitising has the following accuracy: Horizontal: Not less than 90% of well defined data is within 3.5 metres of true position. These accuracies may not be achieved in areas of dense vegetation. Assumed features have no positional accuracy. MHWM, and coincident MHWM and MLWM: Horizontal: Not less than 90% of well defined detail is within 50 metres of true. Attribute Accuracy: Interpretation of aerial imagery and inferences made from local knowledge and selected publications have not been ground-truthed. The accuracy of indicators is based on the accuracy of supporting data and listed metadata reports should be referred to. Where there is insufficient data to determine the classification of a foreshore segment, a category of "unknown" has been assigned. Logical Consistency: This dataset is derived from interpretation of various existing datasets using consistent methods and rule sets. All line segments are checked for duplicate features and correct data attribution. Metadata reports for datasets listed should be referred to for further detail on logical consistency. Completeness: The layer is complete for the intertidal zone of the entire North and Cradle Coast NRM Regions. All segments have been attributed with derived indicator scores or a classification of "unknown". Some datasets supporting segment assessment are incomplete and do not cover the whole study area. Individual metadata reports for listed data sets should be referred to for further detail. Additional: An explanatory report accompanies this dataset and can be obtained from http://www.aquenal.com.au or through the NRM data library.