Managing the unique wetlands of Gippsland Lakes

From a personal perspective, I am very indebted to all those who have undertaken studies of the Gippsland Lakes. In particular, I must pay tribute to Eric Bird. In 1960, I was shown a copy of his just completed PhD thesis submitted to the ANU. It was the first comprehensive geomorphic study of a coastal lake and sand barrier system in eastern Australia that I had read during the time I was undertaking my honours research at Sydney University. I had elected to study the Quaternary history of the “Port Stephens-Myall Lakes area” in NSW, and Eric’s work served as an inspiration. He not only documented sand barrier morphology and history, but also offered evidence for the changing ecological character of vegetation bordering lake shores post the artificial opening of the lakes to the sea at Lakes Entrance in the late 1800s.

In the 1980s I was privileged to take a drill crew to Gippsland and also to spend time with Don Wright and colleagues in the study of beach processes near Lakes Entrance. It was also a time to take students and professional groups to the area on field excursions and become more familiar with the character of the area and the many changes it had experienced over both geologic and historic time. Eric had produced many publications and reports since his PhD days. There was little doubt that the area presented many challenges in establishing a geomorphic history, including for instance the origin of the so-called silt jetties that protruded into the lakes such as the Mitchell River delta. But more threatening and of direct interest to managers were the changes due to salinization of lake waters, reduced freshwater inflows, periodic flooding combined with storm surges especially near Lakes Entrance, and the potential impacts of sea level rise on barrier stability and on lake water levels.

Recently some of these issues have come to my attention through the work of the Gippsland Environment Group and the report of the Victorian Auditor General on “Meeting Obligations to Protect Ramsar Wetlands” (September 2016). I am indebted to Ross Scott for alerting me to this report; it is a must read for anyone interested in the way our internationally wetlands are managed in this country. The Victorian A-G has done a great job in reviewing arrangements between state, regional and federal agencies in the way they are supposed to meet obligations. In general, the review is critical of the Victorian performance while noting difficulties at the federal level; a conclusion reached is that overall, the governance, coordination and oversight of Ramsar sites must improve for Victoria to effectively meet its obligations under the Ramsar Convention. One of the sites mentioned in the report is contained within the Gippsland Lakes region; Parks Victoria has responsibility for the implementation of management plans for this Ramsar site.

One of the key issues is whether the Gippsland Lakes Ramsar site has been adversely affected by human actions. In 2012, the Commonwealth Government concluded that: “Based on the best available scientific evidence, the Gippsland Lakes Ramsar Site had not undergone human-induced adverse alteration in the critical components, processes and benefit/services since the time it was listed in 1982”. This conclusion has been disputed by the Gippsland Environment Group. I also found it quite surprising given my understanding of processes triggered by the opening at Lakes Entrance, as discussed by Bird, and continued dredging over many years. Why would the processes of salinization stop since 1982 if there was continued tidal exchange through this artificial entrance? Was the site visited by officers from the Commonwealth and did they have enough data on which to base this conclusion?

But now the situation gets quite threatening because of plans to dredge the entrance to deeper depths. It comes down to what is now required to maintain a “navigable depth”. I recall the old dredger working away as sand continued to be swept into the flood-tide delta to depths of 2-3m. There is now a requirement from Gippsland Ports to go deeper to 5-6m. At such depths there will in all probability be an increase in tidal flows that will expand the tidal prism. The natural consequence of all that will be more saline waters into the Gippsland Lakes which will impact on the ecological system. This means that under our Ramsar obligations there must be detailed monitoring of the consequences of a permanent opening at these greater depths, with transparent disclosure of information and the potential for the Commonwealth to take steps to reduce adverse impacts.

As in much of coastal management there are issues of trade-offs and priorities, but it is critical for the public to be made aware of just what is happening to this incredible natural system that is the Gippsland Lakes.

Words by Prof Bruce Thom. Please respect Bruce Thom’s thoughts and reference where appropriately: (c) ACS, 2017, posted 21 August 2017, for correspondence about this blog post please email admin@australiancoastalsociety.org

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