Tidal pressures generate estuarine conditions

Letter as published by both The Southern Argus (Strathalbyn) and The Times (Victor Harbor)

Thursday, 10th November 2011

By Trevor Harden

When irrefutable new evidence emerges to challenge a belief that is passionately held, we often find it difficult to adjust, but to reject such evidence is to be deluded.

Recent telemetry monitoring data in the Lower Lakes showed significant estuarine intrusions when high tides pushed strong river flows back through the Murray Mouth and the barrages, with increased salinity detected past Point Sturt and well into Lake Alexandrina.

This confirms the research findings of Professor Rainer Radok during the 1974 floods and the observations of Captain Charles Sturt in 1830 when he noted brackish (saline) water at the very extremity of the lake at Pomanda Point.

It is now beyond dispute that even with the stronger river flows which occurred before settlement and before any extraction occurred upstream, tidal pressures generate estuarine conditions in the lakes. Only the barrages now interfere with this natural process.

To prefer an artificial permanent freshwater lake to the variable estuarine alternative may well be a reasonable position to take when there is freshwater available, but the argument that ‘it has always been fresh’ used by the ‘freshwater only’ activist network to foist their views upon others, is no longer credible.

Trevor Harden

Clayton Bay