Environment Agency inquiry as 50 trout die in Welshpool
The Environment Agency is investigating after fish were killed in a suspected pollution incident in a Powys lake.
Officers were told that more than 50 trout had died at the private fishing pond in Welshpool.
The agency used specialist equipment to pump oxygen into the water overnight to help the remaining fish survive.
The operation at the lake, which feeds the Lledan Brook, may continue through the weekend.
The agency said initial reports indicated that the pollution had turned the water milky in colour.
A spokesman said: "We are very grateful to the member of the public who contacted us about this incident. This pollution is suspected of already killing 50 trout so it is important to contain it within the lake".
"We need to find out where it has come from and how it got there to try and avoid a repeat incident.
"We are also keeping the oxygen levels up to help the rest of the fish in the lake," he added.