Do you know what biodegradable really means? It means that pollutants in the water can be removed by being eaten up by bacteria in the water. That is usually a good thing, particularly in places like sewerage treatment plants. The problem in our creeks and rivers is that the bacteria are living things which need oxygen to survive. If there is too much soapy water or other goodies in the water that they like to eat, then the number of bacteria increases very fast – and then the bacteria use up all the oxygen in the river and there is none left for the fish and other wildlife, so they suffocate and die. This was a tragedy that happened in Queensland as a result of the big floods in 2011, many many fish died in the rivers because so much pollution was washed into the flood waters.
You may think that when you wash your car, it is only a little bit of dirty water that washes off into the stormwater drains. But it is much worse than that. Extensive research has been conducted into the waste water from commercial car washes. This research found that there are large quantities of heavy metals such as lead and zinc, phosphorus, organic carbons, surfactants(dissolved soaps) and all sorts of suspended solids in the water, ‐ many times over the ANZECC guidelines for marine waters. The ANZECC guidelines were set up to protect the marine environment, where dirt in the water that prevents light from getting through to the living organisms is as harmful as the actual pollutants themselves. So don’t wash your car at home unless you have an area of grass or gravel where the pollutants in the water can be filtered through the layers of soil and pebbles and not run into the stormwater drains.
The EPA in each State operates under its own State Laws and Regulations, but they agree in general purpose. In Victoria, the Environment Protection Act 1970, Section 39 states “A person shall not pollute any waters so that the condition of the waters is so changed as to make or be reasonably expected to make those waters
- harmful or potentially harmful to ….. human beings, animals, birds, wildlife, fish, other aquatic life, plants or other vegetation,
- or detrimental to any beneficial use made of those waters.
People should make their own environmentally responsible decisions to ensure that their activities do not result in any pollution going into the stormwater drainage system.
A problem of urbanisation is that building hard surfaces means rainfall is not able to be soaked up into the ground and instead runs into stormwater drains. Our waterways are receiving much more water than they are used to which causes erosion damage to the streams. The stormwater also carries pollutants washed off the hard surfaces which further damage the aquatic habitat. Harvesting stormwater reduces the volume of flow to the creeks and rivers and therefore reduces the erosion damage as well as the pollutant loads. You can help by
- Limiting the extent of hard surfaces and directing the runoff onto grassed areas or gardens.
- Collecting rainwater by diverting roof water into rainwater tanks, and using the saved runoff in gardens, parks and sports fields.