Iron bacteria

Leptothrix spp. · Aquatic life

Where it grows · Photo: Rafael Silva / CC BY-SA

NativeOther organism

Also called Iron ochre, Sheen on the water, Orange slime, Leptothrix ochracea, Gallionella, Iron floc

How to identify Iron bacteria

Fluffy rust orange or yellow brown floc on the bottom or in seepage
Slimy orange coating on rocks, pipes and screens
Oily looking rainbow sheen on still water
When poked with a stick the sheen breaks into flat plates and does not swirl back together
Often near springs, seeps, drain tile and well water inflows

Similar species

Petroleum sheens swirl and flow back together when disturbed and usually smell like fuel; iron bacteria sheens shatter into pieces. Orange clay turbidity settles out and lacks the fluffy texture.

Profile

Season	All year; most visible in spring and in still water during summer and fall.
Starts	Wherever iron rich, low oxygen groundwater enters the pond
Light	Not needed
Depth	Surface film and shallow bottom near inflows
How it spreads or reproduces	Grows in place wherever iron rich water seeps in
Habitat	Where groundwater with dissolved iron meets air: springs, seeps, wetland edges, ditches, drain outlets, wells and pond inflows.

Why it matters in a lake

Harmless to fish, people and pets, but unsightly; it stains rocks, liners and fixtures and can clog pipes, pump screens and irrigation emitters. It tells you the pond is fed by iron rich groundwater.