the region MAKE A COMMENT

6.1.1 threats to the rivers, streams, lakes and wetlands of the region

Stream ecology varies in different parts of the Region, but many streams are degraded in terms of the Victorian River Health Strategy criteria.

Reduced surface water flow and quality impacts on stream ecology. The Moorabool River is one of the most stressed in Victoria.

Degradation of stream condition is widespread, with removal of streamside vegetation, bed and bank erosion, obstructions to fish passage and extensive woody weed invasion, particularly willows and blackberry.

Bed and bank erosion affect an estimated 565 km of river reaches (Draft Corangamite River Health Strategy 2001) with severe ecological impacts on downstream wetlands and estuaries due to siltation, and blockage of saline water moving into the tidal zone (Draft Central West Victoria Regional Estuaries Coastal Action Plan 2001).

There are an average of 55 minor algal blooms a year (surface film, 15,000 cells, duration up to a week) with occurrences spread throughout the Region. There are two to three major algal blooms a year on average (sustained surface scum, > 15,000 cells with duration > 2 weeks), especially in the Barwon and Lake Corangamite Basins (Corangamite Regional Nutrient Management Plan 2000).

Around 540 km of stream reaches are in danger from nuisance plants. Indicative community willingness to pay to return all reaches to good condition and to prevent further deterioration is $5M a year (estimated by Resource Economics Unit, 2002).

Additional information on the condition of and threats to the Region's water resources may be found in the Draft Corangamite River Health Strategy, the Corangamite Nutrient Management Plan and the Draft Corangamite Salinity Action Plan.

6.1.2 threats to surface water flows

Reduced surface water flow is highlighted as a major priority of the Corangamite rural community for a number of reasons, particularly their concerns about future water availability for non-urban or industrial use.

Foremost in peoples' minds is the impact of diversion. As shown in Table 13 - river diversions in the year 2000, diversion by Barwon Water in the Geelong region, under its Bulk Allocation remains within sustainable yield in all three river basins that have extraction for public water supply. (Sustainable Yield is calculated after environmental needs have been considered). However, further growth in diversions will push the system closer to its environmental limits. Of particular concern are the impacts of diversion on summer flows.

"Securing our Water Future", (Victorian Government Green Paper for Discussion, August 2003) proposes caps on further diversions or allocations in the Barwon and Moorabool basins. In these catchments, the proposed caps would be set initially on current entitlement, with steps taken to avoid increase in usage beyond the long-term average usage assumed in developing the entitlements.

Licenses for diversion in summer are now capped, and no additional licences will be issued. Southern Rural Water is the licensing authority, and is working towards a system of Sustainable Diversion Limits for winter flows. Tighter controls will be applied in relation to the size, siting and design of private dams for irrigation or other commercial use given the introduction of the Water Act 1989 (Irrigation & Farm Dams Amendment, 2002).

The Barwon and Moorabool River systems are the most flow stressed river systems in the Region with demand from both urban and rural consumers. Stream flow Management Plans (SFMP) are currently being prepared for both systems.

The Moorabool SFMP commenced in 1998 with its preparation currently suspended, pending the outcomes of a Water Resource Assessment (SKM, 2003). This delay has been in part due to the SFMP process being unable to meet any viable stream flow provisions.

Some river systems in the Otway Coast Basin, such as the Gellibrand River, Barham River, and Painkalac Creek are also utilised for urban and rural consumption. A SFMP has been prepared for the Gellibrand and is currently operating.

There is significant demand for water resources to supply the urban centres of Geelong, Ballarat and the towns along the Great Ocean Road. The urban water authorities and local government will be a key component in the process to ensure environmental flow regimes are maintained.

The effect of runoff of changes in land use and land management practices - including various forms of forestry, raised bed cropping in agriculture, and introduction of filter strips for nutrient control - is not well understood.

Climate change is also a concern. Projections for precipitation trends in the Corangamite Region are still uncertain, but global warming is now undisputed, and this aspect of climate change will increase evaporation and transpiration, and tend to reduce runoff.

6.1.3 threats to surface water quality

Surface water resources are degraded throughout the Region, with elevated levels of salinity (including some natural saline systems), nutrients, and turbidity. Extensive clearing of native vegetation has resulted in widespread erosion and sedimentation problems in waterways producing siltation, nutrient enrichment and numerous occurrences of algal blooms; whilst also impacting on fisheries management, commercial fisheries and tourism - recreational fishing. Urbanisation has also generated high levels of nutrients and toxins particularly from stormwater systems. There has been increasing attention to the quality of wastewater discharges from the larger settlements, but much remains to be done in older systems serving the smaller towns.

Table 14, Indicators of catchment condition in the corangamite region summarises indicators of the condition of (and threats to) the Region's inland surface waters. The lower reaches of most rivers in the Barwon, Moorabool and Lake Corangamite Basins are brackish to saline. The Moorabool and Barwon systems stand out as suffering from both high salinity and high levels of nutrients and sediments. Only the forested upper reaches of the Barwon and Moorabool catchments and most of the Otway Coast Rivers are not impacted by salinity.

Sedimentation and nutrient enrichment (both nitrogen and phosphorus) are serious problems. Persistent blue-green algal blooms are increasing in frequency in the Leigh-Barwon system and in the south west of the Region. These are attributed to several factors, including agricultural and urban runoff, sewage discharges, factory discharges, and some forest operations. Agriculture has an impact due to the intensity of animal production and unrestricted stock access to watercourses in many parts of the Region. These processes are having consequences for the tourist industry, recreational users of rivers and terminal lakes, the eel industry, and downstream wetlands and estuaries. The total cost of toxic algal blooms is estimated at $6-10M a year, (Read Sturgess, 1999).

The Rivers draining the northern slopes (Moorabool, Leigh and Woady Yaloak) are high in salinity. Terminal lakes such as Corangamite, Beeac and Murdeduke that receive inflows from the northern slopes concentrate the brackish inflows and are highly saline. These terminal lake systems are also primary salinity discharge areas, and areas that have always had a high level of salinity (Draft Salinity Action Plan, 2003-2008). Where upland forest has been retained, as in the proclaimed water supply catchments in the Otway Range, water quality remains good. In the proclaimed water supply catchment in the Upper West Moorabool system, water quality remains fair with increasing salinity trends in the Lal Lal Reservoir, which supplies both Geelong and Ballarat. Further research on the causes for this increase in salinity levels needs to be undertaken, as described in the Draft Salinity Action Plan (2003).

The impacts of salinity on most water users are currently moderated by cross catchment water supplies, and to the availability of fresh supplies from the Otway Range. The cost impacts on river water users have not been quantified.

Other water quality concerns include nitrate and phosphate enrichment of surface waters from overland flow and groundwater seepage. It is accepted that human uses of the landscape have had a significant influence. As in any Region with high stocking rates and many intensive rural processing industries, safeguards against contamination with agricultural and industrial chemicals are a necessity.

6.3.1 impacts of human activities on the landscape

The single most important threat to the landscape is the intensification of pressure through greater numbers and demand along the coast, increasing the need for good planning. This is particularly difficult to manage along the Otway coast between Anglesea and Marengo, but is common to all coastal locations.

Changed land use, including inappropriately sited plantations, and increasing density following sub-division in traditional farming areas can also detract from landscape values and catchment health.

Any further deterioration of the quality of rivers, streams, lakes and estuaries adversely affects a range of water-based recreational activities.

6.3.2 salinity

Salinity is a significant threat to land productivity, especially in the Lakes/Plains & Northern Foothills sub-Region.

Table 16 - Provisional estimates of the loss of farm gross margin from salinity ($M / yr)shows the National Land and Water Resources Audit predictions for the Corangamite Region, of costs arising from salinity to agricultural gross margins. Pastures and crops are principally affected.

It is notable that under the "Low" projection there would be very little predicted change in the current level of salinity damage costs to agriculture. Relatively low precipitation and hence groundwater recharge has played a role in this in recent years, given the findings from salinity discharge mapping in 2001 (Salinity Discharge Mapping in the Corangamite Region, DPI, 2001) the increase in areas of discharge during this prolonged climatic dry period only serves to underline the uncertainties concerning future impacts, and the need for a precautionary approach enhanced with further research.

Salinity threatens agricultural production and biodiversity in many parts of the Region. Salinisation of these assets is attributable to complex processes including: (i) the natural soil salinity in some parts of the Region; (ii) regional groundwater systems; and (iii) secondary dryland salinity. The vegetation history of the Region, particularly the early evolution of grasslands over much of the Basalt Plain, in conjunction with the catchments location to the sea, has meant that leaching processes have been underway for a much longer period than in regions where the native vegetation was woody and deep-rooted. Irrigation has not been determined to be a major contributing factor (Draft Salinity Action Plan, 2003-2008).

The Region has been provided with results of the Geospatial Salinity Hazard and Asset Risk Prediction Model. This project used geographic information systems to overlay salinity hazard with social, environmental and economic assets. A ground-truthing program and discussions with affected communities and asset managers has been utilised to establish priority areas for salinity action in the Draft Corangamite Salinity Action Plan (2003-08). Many of the non-market benefits described in the plan refer to the environmental assets of global importance, such as Lakes Corangamite and Connewarre. These lakes, which are Ramsar listed, are under threat of altered hydrological regimes. Both lakes are primary discharge sites at risk of secondary salinity and fresh water intrusions.

Provisional estimates by Resource Economics Unit for the "Salinity Hotspot" areas reviewed in 2000, suggests a Net Present Value (at 7 per cent) of damages to infrastructure of around $10M, equivalent to around $0.8M per year. However, considerably more infrastructure has been identified as being at risk of rising saline groundwater tables outside of these "Hotspot" areas, notably in the eastern part of Greater Geelong. In addition, very conservative assumptions were made about the depths at which groundwater begins to impose costs and the inventory of assets at risk was very provisionally estimated.

6.3.3 pest plants and animals

Pest plants have reduced agricultural land productivity in parts of the Region and impacted upon biodiversity values. European settlement has introduced many pests, including weeds such as gorse and ragwort. As can be seen from Table 17,Weed affected areas, serrated tussock, gorse, ragwort and blackberry are particularly widespread. Serrated tussock was first recorded in Victoria in 1954 at Broadmeadows and was believed to have been there for approximately 20 years (Parsons, 1973).

Animal pests (especially rabbits and foxes) have thrived on both public and private land. It is notable that the rabbit calicivirus spread by CSIRO does not appear to be having as much effect in this temperate area as in drier parts of Australia. Rabbit density is assessed in terms of the number of interventions needed per five-year period. In 1998/99 intervention was needed over four times every five years over some 200,000 ha of public and private land. There was a further 360,000 ha that needed intervention two or three times in every five years. Total impacts on agricultural Gross Margin were estimated at around $5M a year.

Foxes (and some native fauna), that are predators of rabbits, lambs, calves and other small farm animals reach high densities in this Region.

6.3.4 threats to soil

Degradation at both the local and regional level is undermining the values of our soil asset. Soil degradation issues broadly include those affecting soil chemistry (soil chemical fertility), soil structure and soil loss. More specifically, the following key issues are considered to be a priority in Corangamite: soil erosion by water; soil erosion by wind; mass movement; landslides and soil creep; soil structure decline including soil sodicity and waterlogging; soil acidity; acid sulphate soils; and soil fertility decline.

There is an increasing need for the Region to develop a clear understanding of the trends and threats associated with soil degradation and establish actions and targets as appropriate. Improved data is needed on the actual condition of soil and the regional significance of each degradation issue. Understanding the influences on good soil management and encouraging best management practices is required for the Region to be able to plan and invest in this area more strategically. In particular, the CCMA, in coordinating the approach to managing soil health in the Region, needs to adopt a supportive partner role with industry and government by engaging the regional agricultural and forestry industry sectors in good soil management. The CCMA needs to strengthen the work that both the dairy and cropping industries are involved with, as either a research partner or collaborator.

The clear linkages between soil health, land salinisation and water management (soil sodicity, salinisation, recharge, sediment movement and nutrient leakage) require further support and research to integrate management efforts and address the current knowledge gaps on the appropriate management of subsoils.

The development of an appropriate monitoring program is necessary for the long-term evaluation of processes and land management performance, however, combining measures into a single index that can be used has not yet been achieved in the soil health field - nor is it considered to be necessarily appropriate for this Region. The development of a Soil Health Strategy and continued implementation is required to address this important issue. A higher level of management is needed, both of information and of practical response. As a minimum, record keeping needs to become integrated with GIS.

6.4.1 threats to native vegetation

There are two major groups of threats to remnant vegetation, those affecting the extent or quantity, and those that have an impact on quality. Many threats can affect both the extent and quality of vegetation and often a decline in vegetation quality is a precursor to a decline in the extent of native vegetation, and vice versa.

The greatest loss to the Region's native vegetation is attributed to land clearing. Over three-quarters of the Region have been cleared mostly as a result of human activity, including settlement, agriculture, forestry and other primary industries. While recent instances of large-scale clearing are few, significant losses are still occurring with clearing for urban and peri-urban development (especially around the vicinity of the major urban centres of Geelong and Ballarat and coastal areas), and through the use of some agricultural practices. With the predicted expansion of development around these and other areas, the pressure on remnant vegetation is also expected to increase. There are many exemptions to Native Vegetation Retention (NVR) controls, such as housing permits, fencelines and firebreaks, and changes to land zoning (i.e. rural to urban). The lack of capacity for responsible authorities to enforce or implement planning provisions has also allowed the unrestricted clearing of native vegetation. Whilst new clearing restrictions on native vegetation through the State Native Vegetation Framework will be effective, it is the processes that threaten vegetation quality that has the greater impact on remnant vegetation.

The removal of understorey and mid-storey species through rabbits, stock grazing and fire prevention is a common threatening process to native vegetation. These processes often led to the decline of trees and taller shrubs due to the absence of regrowth; the increase in dieback; and the absence of habitat for fauna species that prey on insects that in turn have a detrimental impact on the remaining vegetation. Removing vegetation for firewood, fence-posts and other timber needs, coupled with the collection of individual plants (i.e. ferns, grass-trees and orchids), are all detrimental to native vegetation. Past land-clearing practices have created ongoing problems for today's remaining native vegetation, including, dieback caused by salinity, salt laden wind, high wind exposure and pathogens such as Phytophthora cinnamomi and Mundella Yellow. These continue to have a damaging impact on the Region's native vegetation.

Inappropriate management can also lead to losses in the extent of native vegetation. On both public and private land, through both direct and indirect management actions, native vegetation has been lost mainly through lack of knowledge. An example is the management of remnant vegetation along roadsides and rail lines. Previously, many of these areas were managed through implementing fuel reduction burns that replicated natural fire regimes. Modern methods of control to reduce fuel loads before summer, often involve the spraying of non-selective chemicals during spring, when most native species are flowering. In most cases, once native vegetation is removed, less desirable plants such as weeds and pasture species colonise sprayed areas. These species have higher growth rates and fuel loads and therefore become a higher fire risk than the native vegetation. Other examples of inappropriate management practices include the draining and cropping of wetlands; cropping and its impact on native grasslands; fertiliser and pesticide drift onto native vegetation; and unrestricted timber harvesting of remnant vegetation on private land.

6.4.2 threats to native fauna

Habitat destruction is the principal threat to fauna in the Region. It results from a wide range of activities, including land clearing; and cultivation; grazing of stock on roadsides and wetlands; coastal sub-divisions; inappropriate forest management practices; and impacts of public utilities.

Other threats include degradation of waterways, invasion of areas of native vegetation by exotic species, and predation by feral animals. The latter problem requires an integrated pest management approach, as success with activities like rabbit control may increase the impacts of predatory feral animals, including foxes, cats, dogs and pigs on indigenous fauna.

The main threats to native fish populations come from habitat degradation and competition from introduced species including trout, redfin and carp. Changed water flow regimes and water quality also affect populations and emphasise the need to provide environmental flows.

6.5.1 landscape

The Region's coastline offers many recreational opportunities, but it also faces problems of over-crowding that can spoil the very attractions that people come to enjoy. This is particularly threatening during holiday periods. There is much scope for careful planning of layout and access routes serving holidaymakers and day recreational visitors, and provision of information that helps people to understand the environment and appreciate its needs.

6.5.2 the estuaries

Estuaries suffer from loss of habitat for indigenous species both aquatic and terrestrial, and from changes in flow regime and water quality, notably from sediments, turbidity and eutrophication. Residential growth and tourism development along the whole coastline is accentuating these pressures. In future, climate change may result in increased severity of storms and greater tidal surges, which will also affect the estuaries.

6.5.3 marine waters

Marine pests pose a significant threat to the economic activity and biodiversity values in the area. Introduced to the Region, these pests spread through a variety of means such as ballast water or ship's fouling. North Pacific Seastars, Japanese Wakame Kelp, and Giant Fanworms are examples of pests that have had negative impacts in the Region. Controls are applied on the discharge of ballast waters from heavy shipping entering the Port of Geelong and Port Phillip Bay. There are localised problems with sea floor ecology due to heavy shipping traffic near Queenscliff.

Unlike on land, where ecological processes are generally understood and the impacts of particular actions can be readily witnessed, our understanding of the marine environment is uncertain. The sensitivity of marine and estuarine environments is well understood, however our detailed knowledge of these ecosystems is far from complete. For example, while it is known that sediments, nutrients and pollutants are factors in the decline of some seagrass communities, further investigation is required to determine the exact source of impact and the most appropriate, cost effective actions to protect these environments. Furthermore, the understanding of ecological links to these and other communities is limited. A greater understanding is required to identify measures necessary to manage future activities in the Region to minimise the impact on these communities and processes.