Cape to Cape Catchments

Margaret River

Margaret River and its catchment

The Margaret River is the only true river system within the Cape to Cape region. It is a small river, approximately 60km in length with a catchment area of 470km² (Pen, 1997). The river is considered to be in good condition and is an important attribute to the area due to the social, economic and environmental benefits it brings. Recreational activities, agriculture, education, science, cultural and spiritual values are all supported by the river.

Margaret River town water is supplied by the Ten Mile Brook dam, built on a tributary of the Margaret River. The dam is augmented by water from a pump-back pool on the Margaret River as required.

The upper reaches of the river divide into north and south creek-sized branches. Both of these are within State Forest in the Blackwood Plateau. There are areas of pine plantation in the headwaters, although the majority of the upper catchment is uncleared.

Swamps and floodplains are found along the two upper branches. Due to their relatively isolated location they remain well vegetated and are important wetland habitats. Five of the south-west’s endemic freshwater fish occur in this area, including the vulnerable Balson’s pygmy perch, Nannatherina balstoni, and the restricted mud minnow, Galaxiella munda.

The middle reaches of the river run through farmland. Land use in this area includes beef and dairy cattle grazing, sheep grazing, potatoes, orchards, vineyards, olives and bluegums. Subdivisions continue to occur in this area

Both east and west of Margaret River town the river runs through National Park. The largest tributary, Bramley Brook, joins the Margaret River west of Bussell Highway and is also partially contained within National Park.

Three weirs have been constructed on the river within the town. These weirs constitute a barrier to fish passage and fishways have been constructed to enable upstream migration of native fish and lamprey.

Residential subdivisions continue to occur along the river to the east of town, along with Special Rural developments to the west. Rapids and cascades are common along this section of the river.

Storm water from the town drains to the river and the Augusta-Margaret River Shire Council (AMRSC) have constructed a rain garden on the edge of town to capture the stormwater runoff. This structure has been effective at removing nutrients and sediments from the runoff, preventing it from reaching the river.

The CCG has recently completed a stormwater project in partnership with the AMRSC. The focus was to encourage better stormwater management and sediment loss on building sites, again with the express aim of preventing sediment runoff into the Margaret River.

Much of the northwest side of the river is contained within an uncleared reserve.

Towards the coast the river forms a lagoon which is connected to the ocean by an entrance channel which twists around the headland. The north-western side of the estuary is public bushland and although the land close to the southern bank is cleared, the estuary retains a good buffer of wetland and riparian vegetation along most of its length (Pen, 1997).

Heritage

Aboriginal people have occupied south west Western Australia for at least 38,000 years. The area of land between Bunbury and Cape Leeuwin on the coast, and as far inland as Nannup, was traditionally occupied by the Wardandi group. The Margaret River is known as the Wooditchup by the Wardandi people; John Bussell named it the Margaret River in 1831 after family friend Margaret Whicher.

Rivers, estuaries and wetlands are important to the Wardandi group in both a practical and spiritual sense. Five sites have been recorded with the Register of Aboriginal Sites (Department of Indigenous affairs) on the Margaret River. These include a burial site, two artefact sites, a mythological/artefact site and a burial/artefact site. There may be other sites within the area which have not yet been entered on the Aboriginal Sites Register.

Vegetation

The Margaret River retains many of the features of a healthy waterway. Native fringing vegetation occurs along most of the river, stabilising the banks and providing habitat, shade and leaf litter. There are deep permanent pools, densely vegetated shallow runs, riffles, rapids and cascades, in-stream vegetation, large woody debris and vegetated backwaters.

Very generally, the main vegetation communities along the river are:

• Jarrah-marri forest with blackbutt, bullich and Hakea lasianthoides – east of town
• Karri forest – within town
• Marri-jarrah forest with peppermint (Agonis flexuosa) between town and Caves Rd
  • Heathlands on shallow rocky soils and granite outcrops with Kunzea spp., Darwinia citriodora and Hakea trifurcata – mainly between Bussell Highway and the coast
  • Melaleuca woodland – towards the coast

Species composition within the vegetation communities changes depending on soil type and topography.

Fauna

Species which have been observed along the Margaret River include:

Water rat, Hydromys chrysogaster

Brushtail possum, Trichosurus vulpecular

Western grey kangaroo, Macropus fuliginosus

Southern brown bandicoot or quenda, Isoodon obesulus

The long-necked or oblong turtle, Chelodina oblonga

Hairy marron, Cherax teniumanus

Dusky moorhen, Gallinula tenebrosa

Grey teal duck, Anas gracilis

Pacific black duck, Anas superciliosa

White-faced heron, Egretta novaehollandiae

Cormorant, Phalacrocorax sp.

The Margaret River has many permanent pools and these provide an important summer refuge for fauna. They provide food, shelter and a water source for various river animals including waterbirds, turtles, water rats, fish and crayfish.

The hairy marron is found only in the pools of the upper reaches of the Margaret River. Its numbers are in decline due to competition from the closely related smooth marron, Cherax cainii.

Balston’s pygmy perch and western mud minnow are restricted to fragments of a much larger range. Like the hairy marron, they are found in the river above the cleared agricultural area, in the upper reaches of the Margaret River. Land degradation, a drying climate and increasing water use are probably contributory factors in the decline.

The pouched lamprey, Geotria australis, has historically been found in large numbers in the Margaret River. It moves upstream, negotiating rapids, waterfalls, dams and weirs to reach its breeding habitat.

Resources

The Margaret River Action Plan was produced in 2003.

The recommendations made in the report are used to guide the CCG’s environmental actions along the river.

Fencing, weed control and revegetation projects are carried out in conjunction with landholders, with the objective of protecting the Margaret River and preserving it’s biodiversity values and water quality.

Please contact us for news of current funding available for landholders.

  Margaret River Estuary Project case study