If you see a shiny, oily, sticky, thick sheen of orange sitting atop the surface of your creek, wash, or pond, you’re probably looking at a mat of iron oxidizing bacteria. While that is a mouthful to say, these amazing creatures actually have a simple mode of operation.
To put it simply, these bacteria derive their energy by breaking down the available iron in the water and oxidizing it, leaving behind an orange sludge on the water’s surface. The bright orange material along the stream bank is a mat of bacteria that use the dissolved iron for energy. The orange sheen is the most recognizable, although sometimes the result is yellow, brown, gray, or rainbow-colored.
The product of this chemical reaction is iron oxide, more commonly known as rust, which accumulates in and around the bacteria and gives the mat its orange color. The bacteria cells are practically indistinguishable from the iron oxide particle, even using a microscope.
This iron-filled water can taste unpleasant and leave its brownish stain on pipes, tanks, and containers. It’s not a health risk, although the sludge can reduce the efficiency and flow of well systems, due to clogs in the pipes and screens.
Because of the iron oxide’s ability to clog pipes and wells, some landowners will want to clean the mat from their surfaces. Cleanup options include physically removing the rust mat and using highly concentrated chlorine bleach.
If effort is not made to clean up the mat, it will sustain itself for quite a while. This is because as it grows larger, it’s consuming oxygen, which creates more of an oxygen depleted environment for the remaining iron to expand. It is a strange and amazing phenomenon; a mat will continue to grow until rainwater breaks it up and washes it downstream.
There it must find another habitat in which to spread its orange glow.
