OUR CATCHMENT
King River
Looking forward, looking back: planning and action for the Oyster Harbour
Regional Estuaries Initative
2019 Red Card Feral Animal Shoot
Fire Resilience Workshop
Western Ringtail Possums in Albany: core habitat, Abundance and Distribution
Feral Plant & Animal Control
Porongurup Weed Project
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Available Funding - Nutrient Mapping 2018
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Oyster Harbour Catchment
The Catchment Overview contains information on the following topics:
Location and Geography, Rainfall, Soils, Groundwater, Land-use
Natural assets; Biodiversity, Oyster Harbour, Kalgan River, King River, Porongurup Range National Park and Stirling Ranges National Park
Location and Geography
The Oyster Harbour Catchment is situated along the South Coast is situated along the South Coast of Western Australia and is a part of the South West Botanical. It stretches from Albany through to Tenterden, across the Stirling Ranges to Chillinup and South to, but not including, Two People Bay. The entire area is approximately 3000 square kilometres and includes populated centres of the City of Albany and the township of Mt Barker, Porongurup and Kendenup. There are a total of 48 sub-catchments contained within the Oyster Harbour Catchment.
The Oyster Harbour is the centre catchment of the Albany Hinterland and shares its common borbers with the Wilson Inlet Catchment to the West and Albany Eastern Hinterland to the East. These catchments fall into the South Coast Natural Resource Management Inc. area of responsibility that includes the South Coast, from Walpole in the West to Esperance in the East.
Rainfall varies greatly between the southern and northern parts of the catchment with an annual average of around 950mm closer to the coast, compared to 450mm in the north. Soil types also vary from north to south. The northern and central areas of the catchment are dominated by tertiary sediments over granitic bedrock and the terrain is undulating with low lying stagnant flats. Whilst in the southern parts the soils are derived from granitic material and the landscape is more dissected.
The most common soil supergroup in the Oyster Harbour Catchment is the ironstone gravelly soils representing 28 percent of this area, followed by deep sandy duplexes (20 percent), deep sands (13 percent) and wet or waterlogged soils (12 percent).
​Soil groups are defined within soil super groups and are used to identify the soil component of the land resource datasets maintained by the Department of Primary Industries and Regional Development. Duplex sandy gravel, grey deep sandy duplex and pale deep sandy soils are the most common soil groups in this area, together covering 44 per cent of the Oyster Harbour Catchment (Table 2). All other soils were found in less than 9 per cent.
​Major soil degradation hazards in this area include subsurface soil compaction, water repellence, soil acidity, water erosion and wind erosion.
Groundwater flow systems are local and roughly align with the direction of surface drainage. The more dissected areas have a high groundwater gradient, which allows groundwater to move towards low-lying discharge areas such as creeks and valley floors. Shallow bedrock can partially obstruct groundwater flow and causes hillside seeps in this region. Dykes and shear zones may also affect groundwater flows.
Groundwater levels have had a rising trend. This trend continues until valley floors and creek lines become discharge zones and discharge rate equals the rate of recharge in upper parts of the areas. Salinity, inundation and water logging affects discharge zones and their fringes, where groundwater is <1.5m from the soil surface.
Because groundwater flow systems are local, the salinity issues are caused by recharge in the nearby areas. Treatment of recharge zones in this area will have a quick effect on salinity of landscape and groundwater levels will start to drop a few years after treatments. Growing perennial pastures are the best option in the Oyster Harbour Catchment area. Lucerne is the best perennial for reducing recharge and using groundwater, and Kikuyu is the next best option.
Land-use
​Land use varies with the northern end of the catchment dominated by cropping (wheat, canola and barley) and sheep production. The central region consists mainly of sheep and cattle production with some viticulture and agro-forestry. The lower part of the catchment includes cattle and sheep production, intensive horticulture and agro-forestry plantations.
Natural Assets
The catchment contains many natural assets such as the Oyster Harbour, the Kalgan River, the King River, the Porongurup National Park, the Stirling Range National Park. In total, there are approximately 31 Nature Reserves and 38 listed Heritage Sites within the catchment. These all contribute to the catchment high biodiversity which is a natural asset in itself.
The catchment is located within the Southwest Australia Ecoregion, an internationally recognised biodiversity hotspot (Conservation International, 2017). This was the first biodiversity hotspot identified in Australia, with 15 currently registered (Lambers, 2016; Hales, 2014).
The catchment contains many natural assets such as the Oyster Harbour, the Kalgan River, the King River, the Porongurup National Park and the Stirling Range National Park. In total, there are approximately 31 Nature Reserves and 38 listed Heritage Sites within the catchment.
The Oyster Harbour Catchment has a wide variety of native vegetation assemblages that varies due to soil variations and differences in rainfall. There are 5 known major assemblages found within the confines of the catchment boundaries.
The main vegetation types around the coastal areas include stands of paper barks and reeds around the harbour and wetlands. There are also mixed Jarrah and Banksia heaths and Jarrah and Karri are found on sand dunes. You can commonly find peppermint woodlands in low-lying areas and in between dunes. Slightly inland from the coastal areas you will find low Jarrah, Marri and Wandoo.
Vegetation along the Kalgan River is very different at either ends of the river due to the different climatic environments. Assemblages include low Jarrah and Marri and some Karri, Sheoak and Yate further north in the lower reaches of the Kalgan. You would commonly find low Jarrah, Wandoo, Yate and Mallee in the headwaters of the Kalgan.
The vegetation on the Porongurup include large stands of Karri divided by stands of Jarrah, Mallee and Marri, these commonly mix as well and can be located on the lower slopes. Surrounding lowlands contain mostly scrub with examples of Banksias, Jarrah and Mallee.
The area North of Mt Barker to the Kendenup area contains populations of Jarrah, Marri and Wandoo woodlands with pockets of Mallee and Sheoak woodlands.
The final major area is the Stirling Ranges with varying assemblages from the high to low slopes. The high slopes contain Jarrah woodlands changing into open Eucalypt woodlands on the lower slopes. Vegetation in the valleys usually consists of Jarrah, Marri and Wandoo.
The types and distribution of native animals varies from one end of the catchment to the other. This is due to the different environmental conditions between the upper and lower catchment and changing floral ​assemblages. Some of these species can be found all over the catchment and in neighbouring catchments. There have been 13 recorded examples of migratory birds found around the catchment. The catchment contains approximately 30 mammal species and, 240 bird species, 30 reptile species and an unknown number of amphibians.
Oyster Harbour
Kalgan River
Porongurup National Park
Stirling Range National Park
For further reading on the history, work carried out by the OHCG in the catchment and surrounds, and general information about the catchment, please see:
Various documents produced by Steve Janicke (see: http://janicke.com.au/about-us-2/).
DAFWA: Rapid Catchment Appraisals.
South Coast Snapshot, published by SCNRM in 2017. Available at: http://southcoastnrm.com.au/images/user-images/documents/publications/Snapshot_-_full.pdf
The Condition of the Kalgan River Foreshores 1992/93 published by Albany Waterways Authority, Oyster Harbour Catchment Group Inc and the Department of Agriculture of WA November 1994.
Survey of River Foreshores in the Oyster Harbour Catchment 1997 by APACE Green Skills and Dr Luke Pen, Water and Rivers Commission.
Middle Oyster Harbour Strategic Catchment Project Final Report, November 2009.