The Watercourse Assessment and Prioritised Rehabilitation Plan was prepared in 2011/12 for Sutherland Shire Council. The aim of this study was to assess the condition of watercourses within Sutherland Shire and to develop prioritised rehabilitation actions. The objectives of the study were to:
• establish predisturbance stream conditions
• assess current stream conditions
• identify natural assets, and problems for streams
• evaluate data to determine rehabilitation actions required
• prioritise rehabilitation works
The project involved the assessment of around 250km of streams, divided into approximately 1000 reaches, or stream sections. Shorter reaches had one sample point, while longer reaches had more, so that over 1500 sets of sample point data were collected and assimilated as part of the project. Catchment surveys involved field assessment of predetermined sample points and reaches. Data was collected to inform an assessment of assets and problems, based on catchment setting, geomorphic condition, hydrology, instream habitat, riparian vegetation, water quality and fauna present.
Data analysis involved implementing a scoring system that gave a robust indication of overall stream health across four catchments. Streams were categorised based on their assets and problems Reaches in the more urbanised catchments were further weighted based on stream length. Works plans were developed for each reach, based on field assessment and underpinned by desktop analysis of the catchment. This information was used to inform the prioritisation of rehabilitation actions. Rehabilitation works were designed to move each reach closer to its predisturbance condition, with a particular emphasis on establishing and maintaining a sustainable ecosystem condition.