The amount of E.coli bacteria from human and animal faeces in the Yarra River has fallen dramatically, making it safer to swim for longer in more areas.
Environment Protection Authority data shows that if swimming was permitted around Southgate and Docklands, it would be safe about 40 per cent of the time. Two years ago, stray swimmers would have become ill if they swallowed any water.
The EPA says the improvement in water quality probably has more to do with less contamination washing into the river because of the recent lack of rainfall than clean-up measures such as the State Government's Yarra Action Plan.
According to The Sunday Age's analysis of E.coli data, 10 of the Yarra's 12 monitoring stations recorded much better results than for 2007, the previous time the paper analysed the data.
The improvement in many of the stations was quite dramatic. Docklands, for example, was swimmable for 18 weeks of the year last year compared with just two in 2007.