This is why a river has turned bright green in Longniddry

Some passersby have been alarmed by bright green water in a freshwater river at Longniddry Bents today.

The bright green water alarmed some passersby.

The strangely-coloured water looked “toxic” or “like acid”, said Joanna Pauley, who spotted the vibrant river when out walking the dog this afternoon.

"I thought it might be toxic waste, and I was concerned because it was flowing into the sea," she said.

Ms Pauley put her dog on a lead to stop him drinking the water, and tried to keep her son, 11, away from it.

The bright green water looked like 'something out of Wizard of Oz'.

“He loved it though - it looked like something out of Wizard of Oz," she said.

But the water is not toxic, the Scottish Environment Protection Agency has confirmed.

The bright green is the result of dye testing carried out in the water, and is in no way harmful to humans or the environment.

Dye testing is used to trace the route of drainage systems, in order to check waste water isn't flowing into the wrong place and causing contamination.

Ms Pauley tried to keep her son, 11, and dog away from the water.

It can also be used to trace piping, detect leaks, and study pollution.

The bright dye, which comes in a variety of different colours, is vegetable-based and therefore not harmful to humans or the local ecology.