Pollution which killed 500 fish in Powys river identified

Natural Resources Wales officers carried out inspections of the water over three days

Environmental workers believe the source of pollution which killed hundreds of fish in a Powys river has been identified.

Natural Resources Wales (NRW) said more than 500 dead fish were found in the River Cain, a tributary of the Vyrnwy near Llansantffraid-ym-Mechain.

NRW officers said the likely source was drainage of a wildlife pond and wetland by a landowner.

It is thought nutrients in this water reduced oxygen levels in the river.

Rob Ireson, senior environment officer at NRW, said: "Draining water from a pond to a stream may seem quite harmless - but it is what probably wiped out most of the fish on this stretch of the Cain.

"The water may look and smell normal - but it can be lethal for fish."

NRW said it was likely the fish suffocated when the drained water - which they believe contained low levels of dissolved oxygen and carried nutrients that could reduce oxygen levels even more when they break down - mixed with the river water.