The dwindling river: The Murray mouth

ffThe River Murray empties into the Southern Ocean in Encounter Bay, South Australia. The sea-mouth of the river is situated approximately 10 kilometres south east of the historic river port of Goolwa.

As the River Murray approaches the coast, it forms the terminal lakes of Lakes Alexandrina and Albert (the lower lakes) before dividing into five channels that flow into the Murray Mouth area. The lower lakes are separated from the mouth and the sea by a line of barrages built, in the 1930s, to prevent saltwater entering the lakes, and to maintain higher water levels in the lakes.

At the river's end, the Murray water either flows into the sea or enters the Coorong, a system of tidal lagoons and coastal dunes that stretches approximately 100 kilometres southeasterly from the mouth. The actual mouth of the river is a relatively narrow, and at time restricted, tidal inlet that flows between a much wider gap in the coastal dunes.  This channel is the only open ocean link for the river, and also forms the only connection between the sea and the saltwater lagoons of the Coorong (Harvey, 2002).

The Murray Mouth forms part of the Coorong National Park, and the entire Murray estuary is listed as a Ramsar Wetland of International Importance. Although the environment of the estuary has altered significantly due to European settlement, the lower lakes, Murray Mouth and the Coroong continue to be areas of outstanding national and international conservation value, especially as a habitat for birds (Edyvane, 1996).

Tidal inlets such as the Murray Mouth are very dynamic, and the Murray Mouth is no exception.  Its location and characteristics are determined not only by river flows but also by ocean and coastal processes such a wave and wind action and tidal flows (Bourman & Harvey, 1983). Studies of early reports, surveys and historic aerial photography show significant changes in the location, size and shape of the Murray mouth since W.J. Pullen provided the first survey in 1841 (Johnston, 1917; MMAC, 1983; John Botting and Assoc. (1990); Bourman & Barnett, 1995).

European development of the River Murray, such as regulation, water diversion and construction of barrages, has drastically reduced river flows and therefore the flow of water through the river's mouth. During times of low flow the river fails to reach the sea, and the mouth may be constricted by a build-up of sand. In 1981, the Murray mouth was completely blocked by sand for a few months (Harvey, 2002; Walker, 2002). In a study on the behaviour and future of the Murray mouth, David Walker states:  Low flows and their effects, however, are not a recent phenomenon ... What has changed is the frequency at which the low flow events occur (Walker, 2002).

The traditional owners of the Murray Mouth are Aboriginal Australians - the Ngarrindjeri people.  When writing of their land affiliation, Diane Bell says All the evidence points to the Murray mouth region as a shifting complex of clans, sites, resources and stories. This is where the river, their lifeblood, enters the sea; where ngatji [totems] proliferate;... (Bell, 1998). The Murray mouth area, the place where the mixing of the waters occurs, is culturally and spiritually very important to the Ngarrindjeri, and fundamental to their health (Hemming, 2002).

The first recorded European sighting of the Murray mouth was by Charles Sturt on 9 February 1830. Sturt was disappointed that the mouth did not appear to be readily navigable, writing our fears of the impracticability and inutility of the channel of communication between the lake and the ocean are confirmed (Sturt, 1833: v.II, ch.VI).  Sturt's fears were to be echoed by the colonists that followed. In 1876, William Harcus wrote, The one drawback to this noble stream is the difficulty and danger of exit and entrance through its mouth. The Murray mouth has been a standing difficulty and disappointment to the Colony. It is continually shifting, silting up in one channel and opening out another.  It is exposed to the full sweep of the gigantic waves of the Southern Ocean (Harcus, 1876).

However, from 1853 to 1880, a considerable number of river steamers did 'cross the bar'.  During this time, navigation aids for the Murray mouth were provided in the form of surveys, beacons and buoys, a signal flagstaff, and finally a permanently staffed signal station (Tolley, 1982; Finnis, 1953).  At the same time, a number of schemes to improve the navigability of the mouth were proposed, planned and debated. However, these schemes generally required considerable resources, and were not implemented (Johnston, 1917).

Since colonisation in 1836, the Murray mouth has been the subject of much investigation and reporting - initially to support the development of the river trade, and more recently to address a wider range of concerns relating to the maintenance of the mouth. Closure or constriction of the Murray mouth poses a serious threat not only to the unique ecology of the lower lakes and the Coorong and to the welfare of the Ngarrindjeri people, but also to commercial fishing, agriculture, recreational usage and tourism in the Murray estuary (Edyvane, 1996). A recent report on improving river flows also states the maintenance of the Murray mouth has been recognized as a key objective for environmental management in the Murray-Darling Basin (RMPB, 2002).

As a result of the significant problems facing the River Murray, such as the threat of closure of its mouth, the South Australian River Murray Act 2003 was proclaimed and came into operation in 2003.  Section 7 of this Act establishes 15 Objectives for a Healthy River Murray.  Section 7.3b reads:  The Murray Mouth should be kept open in order to maintain navigation and the passage of fish in the area, and to enhance the health of the River Murray system and estuarine conditions in the Coorong.  The current reporting on progress towards meeting these Objectives is available from the website of the Department of Environment and Heritage, South Australia.

It seems fitting to conclude this brief introduction to the Murray mouth with a quote from Aboriginal Australians - from the Indigenous response to The Living Murray initiative, 2003:  To fully respect the river and all adjoining systems, the mouth of the River Murray should be open.  This can only occur if the needs of the river are respected ...

Further reading

Bell, D. Ngarrindjeri wuruwarrin: a world that is, was, and will be, North Melbourne: Spinifex, 1998, p. 550

Bourman, R. P. & Barnett, E. J. 'Impacts of river regulation on the terminal lakes and mouth of the River Murray, South Australia', Australian geographical studies,  33 (1) 1995, p. 101-115

Bourman, B. & Harvey, N. 'The Murray mouth flood tidal delta', Australian geographer, 15, 1983, p. 403-406

Edyvane, K. [et al].  Biological resource assessment of the Murray mouth estuary,  Adelaide: SA Research & Development Institute, 1996

Finnis, H.J. The Murray mouth, [Adelaide], 1973 [Reprinted from: Proceedings of the Royal Geographical Society of Australasia, South Australian Branch, December 1953, p. 54]

Geddes, M. & Hall, D. 'The Murray mouth and Coorong' in Mackay, N. & Eastburn, D. (eds.) The Murray, Canberra, Murray Darling Basin Commission, 1990, chapter 12, p. 201-213

Harcus, W. (ed.) South Australia: its history, resources, and production, Adelaide: W.C. Cox, Government Printer, 1876,  chapter XVII - 'The River Murray and its trade - The Murray Mouth', p.  94

Harvey, P. Introduction to The Murray mouth: exploring the implications of closure or restricted flow, Canberra: Murray -Darling Basin Commission: (2002), p. 7-9

Hemming, S., Trevorrow, T & Rigney, M. 'Ngarrindjeri culture' in The Murray mouth: exploring the implications of closure or restricted flow, Canberra: Murray -Darling Basin Commission, 2002, p. 13-19

Indigenous response the Living Murray initiative: report to the Murray Darling Basin Commission. (2003), p. 6.  Viewed May 2003 online at: Murray Darling Basin Commission website - Murray-Darling Basin Initiative -The living Murray Initiative website - Informing - Reports [no longer available online November 2009]

Jensen, A. (ed.) River Murray barrages environmental flows: an evaluation of environmental flow needs in the Lower Lakes and Coorong, Canberra: Murray-Darling Basin Commission, 2000

John Botting and Associates. Murray Mouth project : effect of river flows on migration of the Murray Mouth, [Adelaide]: Murray-Darling Basin Commission, 1990

Johnston, E. N. Major Johnston's report on harbor for the River Murray valley: together with plans and plates, Adelaide: Government Printer, 1917 [1913-1917] [Reprinted from: South Australia Parliamentary papers, 1917, no. 38]

Linn, Rob. A diverse land: a history of the Lower Murray, Lakes and Coorong, [Meningie, S. Aust]: Meningie Historical Society, 1988

Linn, Rob. A land abounding: a history of the Port Elliot & Goolwa region, South Australia, Goolwa, S. Aust: Alexandrina Council, 2001

McLeay, Leslie and Nancy Cato. River's end : the story of Goolwa and the Murray mouth, Beverley, S. Aust.: [s.n.], c1985

The Murray mouth: exploring the implications of closure or restricted flow, Adelaide: Department of Water, Land and Bio-diversity Conservation, 2002

South Australia. Murray Mouth Advisory Committee. Investigations into the behaviour of the mouth of the River Murray, Progress report no. 1, [Adelaide] : The Committee, [1983]

South Australia. Parliament. River Murray Act, 2003.  Available online at: South Australian Legislation Acts - R - River Murray Act 2003

Sturt, Charles. Two expeditions into the interior of southern Australia, during the years 1828, 1829, 1830, and 1831: with observations on the soil, climate, and general resources of the Colony of New South Wales, London: Smith, Elder, 1833. vol. II, ch. VI - Channel from the lake to the sea at Encounter Bay [Also available online at:  http://etext.library.adelaide.edu.au/ See: http://ebooks.adelaide.edu.au/s/sturt/charles/]

Tolley, J. C. South coast story: a history of Goolwa, Port Elliot, Middleton and the Murray mouth, Port Elliot, S. Aust.: District Council of Port Elliot, 1982

Walker, D. J. The behaviour and future of the River Murray mouth, Adelaide: Centre for Applied Modelling in Water Engineering, University of Adelaide, 2002, p. 3 [Available online at: Pandora archive: http://pandora.nla.gov.au/tep/43081]

Links

Murray-Darling Basin Authority See: Programs: The Living Murray: Lower Lakes, Coorong and Murray Mouth: Icon site environmental management plans [includes plans for Lower Lakes, Coorong and Murray Mouth]