A report card on the health of the Derwent has found the condition of the estuary improved in many areas in 2012-13.
The 2013 State of the Derwent Report Card summarises monitoring data collected by the Derwent Estuary Program (DEP) and partners in the area between New Norfolk and the Iron Pot Light.
Releasing the 2013 report today, Chairman of the DEP Steering Committee Kim Evans said it provides a watching brief on the state of the Derwent Estuary.
Mr Evans congratulated the program’s industry, government, scientific and community partners for their long-term commitment to the DEP and the resources they have collectively provided to reduce pollution in the estuary.
"Over the past decade the DEP partners have invested more than million in the clean-up of the Derwent and this report card demonstrates the positive effect this has had," Mr Evans said.
DEP Director Christine Coughanowr said the report summarises trends in industrial, sewage and stormwater discharges, monitoring results for swimming beaches, heavy metal levels in sediments and seafood, as well as actions taken to clean-up the Derwent.
"The report shows that environmental conditions improved during 2012 and the early part of 2013, due in part to lower than average rainfall causing a decrease in stormwater and catchment runoff together with an increase in sewage effluent reuse," Ms Coughanowr said.
"Most industrial inputs continued to decline, including organic matter loads from the Norske Skog paper mill, as did the volume of treated effluent discharged by municipal sewage treatment plants."
Nyrstar has undertaken significant environmental projects investing .5 million in addition to .9 million funded through the Australian Government’s National Urban Water and Desalination Plan to improve stormwater management and water recycling at the Nyrstar site.
Nyrstar Hobart General Manager Jeremy Kouw explained that this collaborative industry and government investment has made a huge difference.
"Through our stormwater catchment ponds coupled with the effluent treatment plant we have managed to reprocess 100 percent of stormwater captured over the past 18 months which is an outstanding effort in safeguarding the Estuary," he said.
"In addition we also have our groundwater project which has resulted in the interception of 400 tonnes of zinc from reaching the Derwent Estuary since 2010."
Water quality at the majority of the Derwent’s swimming beaches was classified as either good or fair with the best water quality at Opossum Bay, Hinsby beach, New Norfolk, Kingston beach (middle), Taroona and Little Howrah beach.
However, Windermere beach, the western end of Nutgrove beach and the middle of Howrah beach received poor water quality ratings. Ms Coughanowr said investigations are underway in cooperation with councils to identify and address pollution sources at these sites.
Water quality at Derwent bays and coves was more variable, with continued poor water quality ratings at Marieville Esplanade, Lindisfarne Bay and Geilston Bay; however the Hobart Waterfront has improved significantly.
Heavy Metal levels
A new survey of Derwent estuary sediments indicates a reduction in some of the extreme heavy metal levels previously recorded at mid estuary sites. However, metal levels across much of the Derwent are still well above national guidelines.
Heavy metal levels in Derwent shellfish and flathead were slightly down in 2012, however there is considerable variability from year to year. Levels in Derwent estuary oysters, mussels and black bream remain well above national food safety standards. More information about the safe consumption of Derwent seafood can be found in the brochure ‘Should I eat Shellfish and Fish from the Derwent?’ at: www.derwentestuary.org.au
Key management actions and initiatives carried out in 2012-13:
• Construction of several major stormwater projects in the Glenorchy, Kingborough and Clarence municipalities to capture and treat urban run-off;
• Construction of the 1000 megalitre Duckhole Dam by TasWater to improve the storage and reuse of treated effluent on the Eastern Shore;
• Further investment in stormwater and groundwater management projects at Nyrstar;
• Development and implementation of new oil spill prevention plans at Hydro Tasmania’s power stations, including Meadowbank;
• Annual weed surveys and treatment to eradicate rice grass and prevent the spread of ‘karamu’ into high value wetlands;
• Population surveys and recovery actions to improve the breeding success of the Derwent’s critically endangered spotted handfish; and
• Development of the Greater Hobart Trails website
Ms Coughanowr said the information contained in the annual Derwent Report Card is used by all levels of government, industries and the community to gauge the state of the estuary and the actions being taken to restore our waterway.
For a full copy of the 2013 State of the Derwent Report Card, go to www.derwentestuary.org.au or pick up a copy at Council or Service Tasmania offices.
The Derwent Estuary Program (DEP) is a regional partnership between local governments, the Tasmanian state government, industries, scientists and community-based groups to restore and promote our estuary. The DEP was established in 1999 and has been nationally recognised for excellence in coordinating initiatives to reduce water pollution, conserve habitats and species, monitor river health and promote greater use and enjoyment of the foreshore.
Major sponsors include: Brighton, Clarence, Derwent Valley, Glenorchy, Hobart and Kingborough councils, the Tasmanian State Government, Nyrstar Hobart, Norske Skog Boyer, TasWater, TasPorts and Hydro Tasmania. The DEP has also been supported through grant funding from the Australian Government.