2.2 Topography

Colac Otway Shire has many areas of unique beauty and character, the geography of the Shire varies from lush plains in the north to the rugged and beautiful Otway Ranges in the south with a spectacular coastline.

The Great Ocean Road includes huge cliffs, roaring seas, tranquil coves and safe swimming beaches. The Great Ocean Road passes through a number of coastal towns including Kennett River, Wye River, Skenes Creek, and Apollo Bay. The Otway Ranges is a popular holiday destination for tourists from Australia and overseas.

2.2.1 Environmental Values

The Shire contains some of the most significant environmental assets found in Australia. The municipality has an extensive network of water bodies, some of which are Ramsar listed (i.e. of international significance). In addition, the Shire has over 300 km of very high conservation roadside reserves, as well as approximately 100 km of the internationally recognised Great Ocean Road. This spectacular coastal environment includes not only the coastal dunes and estuaries but also the marine environment.

The majority of the vegetation in the Shire has been cleared since European settlement and although some areas of pristine vegetation remain in the Otways twenty nine of the fifty four vegetation communities in the region are listed as endangered or vulnerable and only nine are not of concern. The Plains Grasslands have been nationally listed under the Environmental Protection and Biodiversity Conservation Act 1999 (EPBC Act) because only very small areas remain intact, the majority of which are on private land.

The environmental assets found in the Shire can be categorised by the Bioregions in which they are found. Bioregions reflect natural boundaries and relationships between biodiversity assets and natural resource based activities. Four Bioregions are found in the Shire; Victorian Volcanic Plain (VVP), Warrnambool Plain, Otway Plain and the Otway Ranges.

Victorian Volcanic Plain (VVP) Bioregion

Colac Otway Shire covers in excess of 900 square kilometres of the VVP that once supported large tracts of the Ecological Vegetation Community (EVC) Plains Native Grassland and Plains Grassy Woodland vegetation. These are now restricted to tiny areas on roadsides, the margins of the region’s brackish and saline lakes and scattered small remnants (usually highly degraded) on private land.

These Endangered EVC’s have been almost totally lost throughout their Victorian range, with only 2.3% of the original Plains Grassy Woodlands remaining (and most of that highly degraded by grazing and weeds), while less than 1.3% of Plains Native Grasslands still exist (DSE 2002). The recent listing of this EVC under federal legislation as a protected plant community indicates that the flora and fauna of this bioregion are some of the most threatened in Australia (Tonkinson 2007). The VVP also hosts internationally protected Ramsar Lakes supporting several rare and threatened waterbirds.

Warrnambool Plain (WP) Bioregion

The Warrnambool Plain extends into a relatively small area of the Shire from the west and is often referred to as the Coastal Plain. The identifying features of the Warrnambool Plain are nutrient deficient soils over low calcareous dune formations. Much of the limestone has been overlain by more recent sediments, and between the limestone dunes, areas of swamplands are characterised by highly fertile peats and seasonal inundation.

Otway Plain (OP) Bioregion

Similar to the VVP, the Otway Plain covers over 900 square kilometres of the Shire. This bioregion includes coastal plains and dunes, foothills with river valleys and swamps in the lowlands. The upper terrain supports Lowland Forest and Heathy Woodland ecosystems, whereas the floodplains and swamps predominantly contain Grassy Woodland and Floodplain Riparian Woodland. Much of this vegetation remains intact on private land and protected in Crown land.

Otway Ranges (OR) Bioregion

The largest, and most protected, bioregion within the Shire is the Otway Ranges. Consisting of moderately steep slopes and moist gullies, this bioregion supports Shrubby Wet Forest and Cool Temperate Rainforest ecosystems on the higher slopes; and Shrubby Foothill Forest on the lower slopes. Large intact examples of these vegetation communities are found in the Shire and remain well protected as over 50% are found in the Great Otway National Park.

Environment Assets

Due to the large amount of clearing there are a number of listed threatened flora and fauna species in the region. Some of the threatened species are listed as threatened in Victoria and some of them are also listed as threatened at the national level due to a greater likelihood of extinction (e.g. Spiny Rice flower).

A large proportion of the Otway Ranges bioregion is protected by being in the Great Otway National Park. This ensures protection of many high value waterways that flow to the sea from the Otway Ranges. However it is worth noting that the Ramsar Lakes located in the VVP bioregion are surrounded by farm land. Therefore these environmental assets face more significant threat of degradation than those located within the national park.

2.2.2 Major rivers, lakes, creeks and reservoirs

Colac Otway Shire has many rivers, lakes, creeks and reservoirs, key waterways are identified in the following table.

Figure 3 - Table of Waterways within Colac Otway Shire

Rivers Creeks Lakes Reservoirs
Aire River Arkins Creek Lake Beeac West Gellibrand Reservoir
Barham River Barongarook Creek Lake Colac West Barwon Reservoir
Barwon River East Branch   Lake Cundare Olangolah Reservoir
Barwon River West Branch   Lake Elizabeth Arkins Creek Weir
Carlisle River      
Gellibrand River      

Figure 4 - Map of Waterways within Colac Otway Shire (click on map to open within interactive portal)

Source: PRIORITY_RIVERS- Department of Environment and Primary Industries – 29/10/2013

2.1 Context

2.3 Infrastructure