Sustainability Report 2006/07Biodiversity
The Port Phillip and Westernport region is home to a diverse range of important ecosystems. These ecosystems comprise extensive terrestrial and marine habitats, and support more than 1860 species of native plants and 600 species of native animals. Of these, 296 flora species and 128 fauna species are considered threatened.
As a significant landholder and waterways manager within the Port Phillip and Westernport region, Melbourne Water plays a leading role in managing, protecting and improving the biodiversity of these ecosystems. In these ecosystems, there are potentially 35 rare, 24 endangered and 38 vulnerable species. There were no changes to this list during the year.
The biodiversity values of the natural assets under our control vary widely. BioSites are sites of extremely high biodiversity value and include internationally recognised Ramsarlisted wetlands, pristine mountain ash forests in protected water supply catchments, and the upper forested reaches of many waterways.
We also manage areas with low biodiversity values, such as heavily modified urban waterways and drainage systems.
The Victorian Biodiversity Strategy is an overarching strategy covering objectives related to the conservation and management of biodiversity. The Regional River Health Strategy, our Biodiversity Strategy and the Waterways Sites of Biodiversity Significance Program provide a strategic approach for biodiversity management in areas under our management.
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Biodiversity Strategy
Melbourne Water’s Biodiversity Strategy, which was finalised this year, coordinates biodiversity management actions across all groups and natural assets, defines biodiversity values on Melbourne Water properties and sets priorities for management of these values. The strategy identifies 29 actions to improve biodiversity management throughout Melbourne Water over the next three years.
Melbourne Water has adopted the Victorian Government’s native vegetation management framework. The framework introduces a ‘net gain’ goal as an outcome for native vegetation and habitat, where overall gains are greater than overall losses and individual losses are avoided where possible.
We aim to deliver a net gain in native vegetation on lands under our management by:
- Avoiding vegetation clearance through appropriate project selection and location
- Minimising impacts through design and management
- Mitigating any losses through appropriate offsets.
We are also participating in the Victorian Government’s Bush Broker Scheme, which will allow us to trade native vegetation ‘credits’ with the overall aim of improving the quality and amount of native vegetation in Victoria. By the end of June 2007, Melbourne Water had not concluded any trades however discussions regarding one trade have since commenced.
Developing a detailed understanding of biodiversity values and collecting additional data on natural assets will help Melbourne Water demonstrate the extent to which effective biodiversity management contributes to an overall ‘net gain’ of healthy ecosystems, vegetation communities and wildlife habitat.
Vegetation clearing fine
In 2006, a contractor cleared 21 mature ironbark trees in an area being managed by Melbourne Water for the installation of an overhead power line within the Sugarloaf Reservoir catchment in Christmas Hills.
The power line is for the operation of new water treatment infrastructure at the reservoir.
The unauthorised clearing resulted from the contractor failing to follow a vegetation management plan developed with Nillumbik Shire Council. Melbourne Water and our contractors each received council fines.
In March 2007, we developed an offset revegetation plan to replant a similar box ironbark forest vegetation class in a nearby part of the Sugarloaf Reservoir catchment.
Under the offset plan, a contractor will replant and maintain the two-hectare site for 10 years. The offset site contains existing remnant ironbark trees and is being replanted with more than 750 seedlings from a variety of species.
Managing data
This year we began work on the Biodiversity Condition and Heritage System, a key aim of the Biodiversity Strategy. The project improves the collection, accuracy and management of biodiversity condition and heritage values of natural assets under our management.
Providing accurate biodiversity information in an easily accessible format to all groups within Melbourne Water, as well as external stakeholders such as government departments, councils, research agencies, catchment management authorities, developers and community groups, will significantly improve our ability to protect and improve biodiversity values.
This database will provide valuable detail on the diverse habitat types, plants and animals found on Melbourne Water property, and will contribute to the Geographical Information System layers managed by the Department of Sustainability and Environment.
Pest animal guidelines
Controlling and minimising the spread of existing pests, and reducing the risk of new pests being introduced are key aims of Melbourne Water’s draft pest management guidelines. The guidelines, which are expected to be finalised in late 2007, will address pest animals such as foxes, rabbits, cats and dogs in protected catchments, reservoirs and land under our management.
New sites of biodiversity significance
Thirteen sites that have high biodiversity values on land we manage were added to the Sites of Biodiversity Significance Program, which now numbers 36.
The objective of Melbourne Water’s Sites of Biodiversity Significance Management Program is the protection and enhancement of regional, state and national biodiversity values through the timely identification and effective management of land.
The new sites include the Wannarkladdin Wetlands at Patterson Lakes, Dunnetts Road Swamp (Plenty River, Yan Yean), the Yering Backswamp (Yarra River, Christmas Hills), the Tamarisk Waterway Reserve and Boggy Creek Waterway Reserve, Boggy Creek (Langwarrin), the Dwarf Galaxia Conservation Wetland (Narre Warren), the Hallam Valley Floodplain (Hampton Park), and the Kayes Creek Waterway Reserve (Derrimut).
Ecological burn-offs
Burn-offs in highly sensitive environmental areas is part of our careful management of Sites of Biodiversity Significance on Melbourne Water land. Low intensity fires promote the growth and diversity of native vegetation communities and help us meet biodiversity management objectives.
Several burns were undertaken during the year, including sections of western basalt plains grassland along the Kayes Creek in suburban Derrimut, and others at Tarnuk Reserve, Westmeadows, and Galada Tamboore on the Merri Creek in Campbellfield.
We also conducted two grassland burn-offs at the Western Treatment Plant, including the Lake Borrie Spit grassland – a site of a nationally significant population of the endangered spiny rice-flower – which was burnt off for the third time in four years on the advice of botanical consultants. The burns were conducted by our catchment fire fighting team.
BioSite surveys
Ecological studies of two highly significant sites of biodiversity, or BioSites, were conducted in the protected catchments of Yan Yean and Cardinia reservoirs this year.
The studies involved a general fauna species survey, mapping and assessment of native vegetation, and mapping of weed invasions. Fauna surveys involved trapping, spotlighting, call playback and active searching during the day and night. Mapping and assessment of habitat was also undertaken.
Study results will assist with management and future enhancement of the high biodiversity values of these BioSites, and further detailed surveys of other Melbourne Water BioSites are planned.
Case study
Balancing birds and bugs
A trial project in which small quantities of treated effluent are trickling across mudflats on the shorelines next to the Western Treatment Plant could resolve a looming dilemma for Melbourne Water and provide a feeding bonanza for waterbirds.
The multi-outlet trial seeks to balance Environment Protection Authority (EPA) requirements to reduce nutrients and treated effluent volumes entering Port Phillip Bay with our international responsibilities to protect birdlife and the Ramsar-listed mudflats on the bay’s western shoreline.
Melbourne Water senior wildlife and wetland scientist, Will Steele describes Melbourne Water as the “jam in the sandwich”, because reducing nutrient loads and volumes of treated effluent is expected to reduce the algae, bugs, worms and other food sources that support large populations of migratory birds.
At present treated effluent discharges into Port Phillip Bay from four outfalls. The multi-outlet trial involves dispersing water siphoned from treatment lagoons and distributing it along 10-metre pipes via tiny holes.
“We have migratory birds that travel halfway around the world to feed at these mudflats,” Will said. “The trial multi-outlet pipe is a bit like a t-section downpipe that spreads water collected off a roof. But instead of heading out into the bay in a large stream, the water trickles across the mudflats. This allows the biodiversity within the mudflats to make greater use of the nutrients, which in turn provides food for the birds.”
Will said the four multi-outlets were working effectively, and with technical issues resolved, the trial will be used to assess the impact on the mudflats’ biota and birdlife.
