At the July meeting of Mayo County Council, Cllr Al McDonnell raised concerns about Lough Carra and what he described as "dramatic change in the ecology" in the lake.
Cllr McDonnell, who lives near the lake, has major concerns about how the changes he has seen over the last few years will affect the quality of the drinking water from the lake.
He told the meeting: "I'm sad to report that there is a dramatic change in the ecology of Lough Carra, I live on the lakeshore and spend time on it. But above all I drink the water as do well over 1,000 others."
He pointed out that the lake also flows into Lough Mask which is the major water supply point for central, south, and east Mayo. "It's also important to remember that Lough Carra is six feet higher than Lough Mask and it flows continuously into Lough Mask and every person in this town [Castlebar] and over a wide area is drinking the water from there," he said. "So if there is something wrong in Lough Carra, it is being transported directly to Lough Mask."
Describing the changes that he has noticed Cllr McDonnell said: "There's a change in the apperance of the floor and the bed of the lake, because Lough Carra is a limestone lake and it's coloured quite cream in colour and you can normally see to the bottom of it. Now it's becoming increasingly dark and black over wide areas, all this is accompanied with the dramatic increase in unidentified vegetation which wasn't seen there before." He went on to call for all the different government agencies that deal with water issues to get together to find out what is going on in the lake and to make sure that it is sorted, saying: "We need an urgent meeting of all the agencies capable of carrying out the work and we need it now, it's not a matter for 2016, it's a matter for now."
The councillor also issued a plea for it to be fixed now saying: "It's a worrying change, I can do without the fishing, but I can't do without the water."