Lead, cadmium, zinc and copper in organisms of Lake Macquarie

Lake Macquarie, the largest of many similarly-formed estuarine lakes on the NSW coast, was created by the inundation of a series of confluent river valleys due to a relative rise in sea level during the post-glacial transgression. The potential for effulent-induced pollution of the lake basin is partly governed by several physiographic and hydrologic features of Lake Macquarie. Tidal action is effectively damped by the restriction of flow caused by Swansea Channel. A number of small ephemeral or intermittent streams drain into Lake Macquarie from a catchment of 74,000 ha but most freshwater input comes via Cockle Creek at the northern end and Dora Creek on the south-western shore. Winds prevail from the south-east quarter in summer and from the north-west in winter with periods of transition between the major seasons. Sedimentation of the original valley system has created a rather flat-floored, shallow basin. Lake Macquarie's constricted and elevated entrance channel, small freshwater input, restricted wave and current action and the general basin morphology all result in a markedly depositional environment.