Environmentally friendly stormwater options - open waterways

Water quality improves in situations where open stormwater drains are treated as natural waterways. Open waterways encourage fish and other aquatic life and improve water quality.

Piped systems are generally not designed to handle infrequent major stormflows. While concrete channels and pipes can efficiently remove stormwater during major storms, contaminated stormwater flows directly to the sea and if the channels and pipes are not large enough flooding may occur. Riparian planting and raingardens may contribute to more effective stormwater management.

What is rusty water?

Rusty water in streams or waterways isn't always polluted water. The rust coloured water can be caused by a common natural occurrence. Oxidised iron deposits mixed with water lead to compounds called iron oxy-hydroxides.

Water flowing through the city's stormwater system or other waterways will often contain dissolved minerals from the rocks, land and sand that it contacts. One of the major components of rock is iron, and that dissolves in the water.

A common grey/green rock, greywacke, turns brown when exposed to air or air-impregnated water for a long time. The same happens to the water with the dissolved iron in it. If left exposed, the dissolved iron turns brown, as it reacts with the oxygen.

Water in streams and waterways has often travelled over surrounding hillsides and contains dissolved iron. When it emerges into the air and is aerated, the iron oxidises and falls out of the solution, producing the brown deposit entirely naturally.

Over time, huge deposits of iron oxy-hydroxides can form. Deeper waters tend to have more iron in them, mostly because they have had more time to dissolve the rocks.

Regard iron-stained water at the bottom of the local creek as a friend and ally, an indicator of underground water seeps, there to help clean up our environment rather than act as a pollutant.

What you can do

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