The Northern Ireland authorities were under fire today over the destruction of hundreds of rare mussels in a protected river in Co Tyrone.
The North's Department of Environment was criticised by conservationists after it emerged officials were alerted in April to a pollution risk from a contractor carrying out pipe-laying work for the Water Service on the Upper Ballinderry River near Cookstown.
The contractor changed his work practices following a warning from the Britain's Environmental and Heritage Service (EHS).
Almost three months later, hundreds of dead freshwater pearl mussels were pulled out of the river, wiping out 10 per cent of the endangered species. Another 5 per cent were removed to safety after the EHS authorised the Ballinderry Fish Hatchery to do so.
However, an investigation by the EHS's water pollution team found no evidence they were killed by pollution.
WWF Northern Ireland freshwater policy officer Dr Alex McGarel queried the service's handling of the incident.
"The Department of the Environment (DoE) has acknowledged there was a pollution problem on the river in April and yet nothing proactive appears to have been done until July, other than a warning to the contractor and a letter to the Water Service," she said.
"Anybody who knows anything about water pollution knows that a lot of transient damage is done.
Freshwater pearl mussels were once common throughout the British Isles but the population has dwindled because of over-harvesting, habitat reduction and industrial and agricultural pollution.
In Northern Ireland, the population is confined to the Upper Ballinderry and Owenkillew Rivers in Co Tyrone and the Cladagh River in Marble Arch, Co Fermanagh. A DoE statement confirmed members of the EHS's pollution team responded to concerns in April when the contractor was engaged in practices which threatened the river.