The most significant threat to the ecological character of the Ramsar site is climate change (EPA 2010) and this has already had a dramatic impact on the site.
Actual or likely threat or threatening activities Potential impact(s) to wetland components; processes and or services Location Likelihood’ Timing Climate change reduced rainfall Lower water levels leading to increasing salinity.
However; there is strong evidence to suggest that there have been significant changes to the ecological character of this site; primarily as a result of drought and climate change.
Moreover; there is XV evidence to suggest that other wetlands in the region (for example; Lake Purrumbete and Bullen Merri) have retained better ecological values and are expected to be more resilient to climate change (EPA 2010).
Actual or likely threat or threatening activities Potential impact(s) to wetland components; processes and or service Location Likelihood Timing Climate change drought All Certain Current Lower water levels leading to increasing salinity.
However; there is strong evidence to suggest that there have been significant changes to the ecological character of this site; driven by climate change.
The three aspects of climate that most directly affect wetland ecology are rainfall (both local and in the catchment); temperature and (to a lesser extent in temperate systems) relative humidity as these all fundamentally affect wetland hydrology and the water budget.
The most significant threat to the ecological character of the Ramsar site is climate change (EPA 2010) and this has already had a dramatic impact on the site (see Section 7).
As such threats are considered in two categories Climate Change (and associated additive and synergistic factors) and local scale threats.
Water resource development (drainage) Climate change (drought) Pollution (agricultural run off) Threat Pollution (urban wastewater) Biological resource use Invasive species Agriculture (grazing) Increased salinity Decreased water levels Increased nutrients Duck hunting Weeds (littoral zone) Physical disturbance Stressor Loss of breeding and feeding habitat Increased phytoplankton Species mortality (invertebrates; fish; vegetation) Species mortality (waterbirds) Increased competition Altered community composition Ecological effects Changed wetland type Hydrology Services Diverse wetland types Component; process; or service Waterbirds Services Physical habitat; priority wet land species Vegetation Services Threatened species Physical habitat for waterbirds Figure 42 Stressor model of the Western District Lakes Ramsar site (after Gross 2003 and Davis and Brock 2008). 5.1 Climate change Williams (1995) stated that salt lakes are more susceptible to impacts of climatic change and altered water regime than freshwater systems.
Reconstruction of climatic data and lake water levels on a couple of lakes in the region has shown that there has been an ongoing decline in levels since 1841 however anthropogenic induced climate change is likely to severely exacerbate the situation (EPA 2010).
Overall; drought and climate change have had a significant impact on the lakes of the Ramsar site; evidenced by the severe and rapid changes observed at Lake Corangamite.
The potential effects of climate change on the hydrology of the lakes within the Ramsar site has been modelled by Water Technology (2010).
For example; the modelled hydrology for Lakes Colongulac and Murdeduke with climate change (2030 scenario of lower rainfall and increased temperatures) and under current conditions illustrate the dramatic nature of predicted impacts.
However; under climate change scenarios; the reduced inflows from rainfall and overland flow; together with increased evaporation from predicted warmer temperatures; results in an increased net loss of water.
Similarly; the reduction in surface water inflows and increase in evaporation under climate change scenarios is predicted to result in a decline in water in Lake Colongulac.
Due to the strong linkages between salinity and hydrology at the lakes within the Ramsar site; impacts of climate change have and will continue to extend to altered salinity regimes.
Changes to hydrology and corresponding changes in salinity have been attributed to the persistent drought in the region (Barton et al. 2008).
Groundwater surface water interaction and the impact of a multi year drought on lakes conditions in South East Asutralia.
The 1997 2009 drought has also had notable impacts on the groundwater tables of the region (Tweed et al. 2009).
This is consistent with the findings of Tweed et al. (2009) who indicated that impacts of the drought have increased lake salinity levels by approximately 2.8 times over a nine year period to 2006 (Tweed et al. 2009).

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