Sydney has one of the most beautiful harbours in the world but as out city attracts more people the human waste they generate is making it unsafe for swimming. We have just had one of the driest summers on record and when the water was tested on March 15 the contamination count was way above a safe level.
The problem is the amount of enterococci bacteria that is released from sewage. The safe level is below 40 parts per 100 ml but this was exceeded in most parts of the harbour. The beach at Rose Bay recorded a level of 175 and the Parramatta river recorded 70. In many instances, readings way above 500 were common.
The usual outcome of swimming in contaminated water - is to get a bout of gastro. The health people report that is a sort of " unlucky lottery ". Should a group of a hundred people go for a swim it is likely that about ten would have gastro a day later - and ninety would not be affected. Such is the way this capricious bug affects individual people.
We are warned not to enter the water for at least three days after a rain event because heavy rain causes the sewer system to overflow and all this runoff goes into the harbour. Even in a dry period there is an amount of contamination from aged leaking pipes, plus the fecal animal matter washed off our streets and nature strips.
Treating sewage to a safety level is costly and unfortunately we humans have the habit of treating our sewers as general waste disposal channels. The latest craze is to replace toilet paper with what are known as "wet wipes " - and this is an absolute disaster when it arrives at the treatment facilities. Wet toilet paper dissolves in the digestors. Despite the claim on many wet wipe products that they are "sewer safe " they fail to break down and clog both the arterial pipes and bring the treatment plants to a standstill. There are fears that if this practice increases our entire sewer system could fail.
That is one of the reasons that the water and sewage people have plans for more overflow pipes to take the pressure off by bypassing the sewage plants and taking runoff water into the harbour when storm events occur. We already have outlets that deliver the treated effluent several miles out to sea but as more people cram into our city we are having to cope with increased sewage volumes - and it seems that global warming is increasing the intensity of the storm systems that visit this city.
What these latest tests disclose is that swimming in our harbour delivers a risk even when the weather is mild and there has been no rain for many days. It seems that Sydney harbour is becoming a pictorial backdrop to the city, rather than a functioning harbour that is safe for swimming. Many people accept that risk, but they do so with the likelihood that from time to time they may suffer a bout of gastro.
The wise will do their own evaluation - and never enter the water in the aftermath of one of Sydney's summer rain events !
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