If a watercourse is polluted with oil, you will see different visible effects depending on the amount.
Small amounts of oil on a river, canal or lake will appear as a thin dull layer on the surface. Generally, this means that the quantity of oil is very small, but we will still investigate. It is possible that there will be no smell of oil in the air unless you are close to the source of the pollution.
The next visual clue to the presence of oil is a “rainbow” sheen which we call irridescence. This may be visible across all or part of the water. At levels of oil contamination such as this we will install some absorbent booms to collect the floating oil whilst we try to identify the source of the pollution.
Larger amounts of oil will also show as a dull layer, and may be coloured with a bluish or reddish tint if it is Diesel. If you were to throw a pebble into the water, the layer would seperate, briefly showing rainbow colours and then the oil will re-combine. Sometimes there may also be patches of rainbow colours in faster flowing sections of the water. Generally at these levels of oil you will undoubtedly be able to smell it and even identify its type. These oil pollutions are likely to be serious and can cause significant damage to water birds, marginal plants and potentially kill fish.
Lastly, you occasionally may see a dullness and/or rainbow effect on the water which isn’t due to oil pollution. Its caused by a naturally occurring bacteria which i will describe in more detail in a later post.
As always, if you suspect that a watercourse is polluted, give us a call straight way on our freephone number 0800-807060.
More information on oil pollution can be found on our website:
Oil Pollution – The Environment Agency’s view
