How has pollution affected the Yarra River?

Answer 1

The Yarra River (an aboriginal word meaning "running water"), flows 246 km from Mt Gregory in the Eastern Highlands of Victoria to Hobson's Bay in Port Phillip Bay. It was discovered by Charles Grimes in 1803. The River mouth was a swamp which was interfered with by man to provide the requirements of the Port of Melbourne.

In the first years of settlement around the Yarra River, which was during and after the 1830s, the Yarra was mainly used for washing clothes, bathing, drinking, irrigation and fishing. This was normal behaviour for the time and, whilst not exactly desirable, did not cause long-lasting problems.

Clouding of the water started in the mid-1800s when extensive land clearing and farming along the Yarra and development in the lower reaches resulted in the presence of microscopic clay particles wich remain in the water due to turbulence in areas of the middle and lower sections of the river. When the fresh water of the river meets the marine salts as it enters Port Phillip, the suspended particles clump together and sink. This in itself is not a problem, though it results in discoloured water.

The biggest problems have occurred in the twentieth century. Heavy industrialisation in the settled areas along the river has led to enormous problems of waste and toxic materials in the water. The problem has compounded to the point where, early in the 21st century, kayakers on the river have contracted illnesses such as leptospirosis from their contact with the water, and at one point hundreds of dead eels were discovered (in 2005.) There have been successful attempts to reduce the levels of ecoli bacteria in the river - down from their levels in the 1970s - but these levels remain up to 22 times higher than what is safe for swimming.