Pollution which killed 500 fish in Powys river identified
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.