This is the mouth of the King River, otherwise known as the Dead River as nothing lives in or around it due to pollution from mining.

From Tasmanian Resource Planning and Development Commission site http://www.rpdc.tas.gov.au/soer/casestudy/16/index.php):

"The King River is arguably Australia’s most polluted river. Mining started in the 1880s, with the Queen River, a major tributary of the King River, being used for waste water disposal from the Mt Lyell copper mine. Between 1922 and 1995 low grade ore was concentrated on site and the tailings (ore-washing residue) dumped in the river also.

About 1.5 million tonnes of sulfidic tailings entered the river system each year up to 1995, along with huge volumes of acidic, metal-rich water flowing from the workings. This ‘acid mine drainage’ is derived from water leaching through the exposed and oxidised sulfide rocks. When it was in operation, the fumes from the ore smelter produced acid rain which also leached minerals from the bare Queenstown hills.

In 1992 the King River was dammed above the confluence with the Queen River to generate hydroelectric power. This changed the flow regime in the King River, and affected the way tailings were transported through the river system. The tailings in the river greatly affect the water quality. Being alkaline they neutralise some of the acid water draining from the mines; they also provide surfaces to which the metals adhere, thus greatly reducing their effect on the biota.

About 100 million tonnes of tailings have been deposited on the banks and bed of the King River and in a delta at the mouth of the river where it enters Macquarie Harbour.

Since the closure of the mine in late 1995, and the construction of a tailings dam by the new operators, tailings no longer enter the river system. However, acid water continues to enter the river due to mine dewatering and run-off from the waste rock dumps. Without the buffering previously provided by the alkaline tailings, the acidity in the Queen and King rivers has increased, and dissolved metal concentrations have greatly increased—to levels highly toxic to aquatic life."