Faughan Anglers have claimed there had been indications of water quality problems for weeks before the two major fish kills at Campsie and Claudy this week.
Secretary Gerry Quinn, speaking on behalf of River Faughan Anglers, claimed the response from authorities “appears to have been inadequate at best”.
“On Tuesday we had reports of a catastrophic fish kill above Claudy, which was bad enough, but to add insult to injury NI Water emptied the dam at Campsie, a long stretch of deep water holding large numbers of fish, and we witnessed a second fish kill yesterday evening (Tuesday).”
He said that for years anglers have raised concerns about developments along the river despite its designation as a special area of conservation in respect of Atlantic salmon and European otter.
“Our fears that a pollution incident might cause catastrophic damage to fish stocks and the habitat generally have been realised over the past few days,” he said.
He further claimed that there seemed to be no “emergency plan” to deal with incidents like that which has unfolded “or if there is it collapsed into farce”.
A spokesperson for NI Water responded: “Following a pollution incident in the River Faughan, it is normal practice for NI Water to raise the weir gates located at the Faughan Pumping Station intake so that contaminated water can be flushed down the river and past the pumping station intake.”