Oxley Creek catchment is experiencing rapid population growth and urban development. This creates a great demand for residential land, building materials, transportation networks, industrial and manufacturing areas, and waste disposal facilities.
The Urban Water Cycle
In Brisbane, reticulated water is treated before it enters our homes and factories in pipes. We use it for drinking, washing, gardening, and in toilets. Any wastewater leaving our sinks and toilets then travels from our homes and factories into the sewers and on to the wastewater treatment plants. Treated wastewater is released into the local waterway, often with nitrogen, phosphorus and bacterial levels permitted by state government licences.
Urban areas produce a lot of runoff from:
- An increase in built up areas that do not easily ‘soak up’ water
- Extra water entering the system from everyday activities such as watering the garden or washing the car
Waste water treatment plants do not treat urban runoff. After a storm, runoff moves from sealed surfaces, to gutters or drains through stormwater grates, into pipes and then into the local waterway. Rubbish and other contaminants such as car oil, animal faeces, fertilisers, and weed sprays carried in the runoff all ends up in the waterways. Runoff also carries ‘natural’ contaminants, such as grass clippings, soil, and leaves, which increase the nutrient load in waterways. This can cause algal blooms and make the water foul – a process called eutrophication.
What you leave on the roads or footpaths today, ends up in the creek tomorrow. While a good downpour cleans paths and drains of rubbish, and the streets of oil and grit, the rubbish does not disappear, it just moves into our waterways!