Iron bacteria has bloomed in several areas across the Blue Mountains following the sustained wet weather.

Resembling an oil slick, the harmless bacteria (also known as Iron-oxidizing bacteria) lives underground, feeds on iron-rich water and creates an orange or rust coloured slime.

Ground water is low in oxygen, and this limits the growth of bacteria, however when groundwater rises to the surface via creeks, cracks and pipes, the oxygen in the air acts like a fertiliser for the bacteria and it can grow quickly leaving a rust coloured and slippery slime in the water.

"The sustained and excessive wet period has resulted in the presence of iron bacteria flocculates appearing as orange blooms," said Blue Mountains mayor Mark Greenhill.

"Iron bacteria is not dangerous and poses no health risk to the community. It is, however, very slippery, so care should be taken when walking in and around bodies of water that contain iron bacteria."

Iron bacteria looks unappealing and is often mistaken for an oil spill, but poses no environmental risk as it is naturally occurring. However, in extreme and rare cases, it has been known to overgrow and block water infrastructure.

Common areas for iron bacteria blooms to occur include creeks that are fed by groundwater, steep slopes where water seeps out from the ground and water infrastructure (such as piping/guttering) that have groundwater sources.

Download the fact sheet on Iron bacteria

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