The Environmental Agency confirmed that the mysterious green substance in the water at Swanpool on Friday was most likely the result of a harmless dye that was added to trace the flow of water.

The bright green colouration led to some speculation that run off from a nearby industrial estate could have polluted the water, or that a harmful algae bloom could be affecting the ecosystem.

But it is now thought that the unnatural colour was actually caused by dye tracing, which is a method that involves using dye to identify and analyse the flow of water. The Environmental Agency has confirmed that the dye had no impact on wildlife and has since been flushed out of the ecosystem.

In August of last year, dozens of fish died overnight when an algae bloom dramatically changed the levels of oxygen in the water and the fish weren't able to adapt to the conditions. The water at Swanpool has rare brackish conditions, meaning that saltwater and freshwater mix to create a unique habitat for wildlife that couldn’t exist in other places.

A concerned Packet reader sent in these photos of the brightly coloured dye in the water at Swanpool.