Supervising Scientist Report 168
Supervising Scientist, 2001
ISBN 0 642 24374 3
- SSR168 - North-east rivers environmental review: A review of Tasmanian environmental quality data to 2001 (PDF - 687 KB)
About the report
The north-east of Tasmania encompasses the South Esk River basin, rivers draining into Bass Strait east of the Tamar, and rivers discharging to the east coast of Tasmania north of Scamander. The area incorporates a wide range of riverine environments, ranging from small streams draining high plateau regions, to large rivers that are highly regulated and impacted by land use activities. This report provides a summary of the environmental status of waterways in the north-east region based on published information. Current water quality issues and current water management activities are presented on a catchment basis.
Overall there is a lack of long-term water quality information available for north-east waterways. The recent 'State of the River' reports (Bobbi et al 1996, 1999a,b,c,d) have greatly improved the understanding of water quality and riverine health in a number of waterways, but more information is required to assist catchment managers and the community in identifying issues and priorities.
Riverine water quality issues identified in this review include run-off from agricultural and forestry land, high levels of bacteriological indicators due to stock access to rivers, leaching from septic tanks, poorly performing sewage treatment facilities, and acidic discharges from historic mining centres. Generally, industrial wastewater discharges were not identified as a significant water quality issue except where occasional accidental releases occurred.
The region is characterised by a dispersed population, with the largest towns having fewer than 5000 residents. The low population density has limited local Councils’ ability to provide adequate sewage treatment to all residents. Septic tank usage is high outside of the major population centres and although not quantified, it is believed they are impacting downstream water quality.
Impacts from land use practices are a major issue in north-east Tasmania. Turbidity and elevated nutrient and bacteriological loads have been documented during and following rainfall events in many rivers in the north-east. These impacts are most pronounced in agricultural areas where riparian vegetation has been damaged or lost and stock has direct access to waterways. Habitat destruction threatens several aquatic species, such as the giant freshwater lobster and freshwater snails. NHT (Natural Heritage Trust) funded projects are beginning to address these issues in most catchments through the implementation of Rivercare plans.
Many of the sewage lagoon systems in the north-east have been upgraded in the past few years through the NHT Clean Quality Water Program. Notable exceptions are the Longford sewage lagoon system and Scottsdale sewage treatment plant. The Longford facility discharges into Back Creek which is also severely impacted by intensive agricultural practices in the catchment. The Scottsdale STP discharges to Cox’s Creek, which is impacted by dairying, forestry and direct stock access.
Storys Creek, tributaries of the Ringarooma/Boobyalla system, and the George River catchment receive acid drainage from historic tin mining sites. Some remediation work has been completed at these sites, but elevated metal concentrations and low pH values continue in parts of the catchments. Near Gladstone, acid drainage affects waterways used for recreation.
Coastal areas in the north-east are used extensively for recreation. An analysis of the estuaries has indicated that most are impacted to moderately impacted, and except for the Boobyalla and Tamar, are of little conservation value. The presence of introduced marine pests in Henderson Lagoon and elevated levels of Tributyl-tin in sediments in Georges Bay are newly recognised additional stresses on these estuarine waterways.