Grave pollution fears for Lough Carra

IRELAND’S only natural limestone lake, Lough Carra, will be completely polluted within 10 years unless immediate action is taken to stop the current inflow of nutrients to the 4,000-acre lough in south Mayo, writes Tom Gillespie.

That's according to Councillor Al McDonnell, who has been campaigning for years to highlight the dangers to the lake and the 2,000 consumers who depend on it for their water.

The lake is approximately six miles long and varies in width from 400 yards to one mile.

It lies to the north-east of Lough Mask and is often overshadowed by it, but Carra is recognised as one of the best wild brown trout lakes in the country.

Councillor McDonnell, who is cathaoirleach of Mayo County Council, was born on the shores of Lough Carra. A keen angler, Al is fearful as to the future of the lake.

He explained: “There is a dramatic change in the ecology of Lough Carra, a significant change in the last 10 years but a dramatic change in the last five. It is quite extraordinary now.

“The source of the problem has not been identified. I have been campaigning for well over a year now to have it scientifically investigated and to identify the sources of additional nutrients that are actually going into the lake.

“A number of observations that we made over the years included a dramatic increase in aquatic vegetation, some of which has not been seen in the lake before, and the change in the colour of the bed of the lake.

“It is probably the only natural limestone lake in the country and the bed is a natural beautiful cream/gold colour. But now 99% of it is coated with with a dark green coating that looks black from the surface.

“There are several hundred acres covered with it now. The turnover time of the lake is four years to flush itself out.

“On May 16 last, thanks to the environmental section of Mayo County Council, with Larry Walsh and his team and Frank Kennedy, the top scientist with the Environment Protection Agency (EPA), we carried out a survey of the lake.

“We brought two boats out. We could not have gone out on a more suitable day. It was flat calm. It was a beautiful May day. We travelled all of the lake and we took samples from the bed, the reeds and of the new vegetation, and instantly the scientists said there is a problem.

“They immediately changed the status of the lake from ‘good’ to ‘review’, which was a pretty dramatic development. Up to that point they had only taken samples from the actual lake itself.

“But we identified a number of inflows where there was far more evidence of nutrient concentration.

“Lough Carra now, on the EPA map, includes the catchment area to which all the inflow rivers come from.

“Since May 16 there has been significant sampling of the catchment where seven to eight additional sampling points have been pinpointed. They have a lot of data on the system at the moment.

“They are not releasing any results just yet but when the water flow increases over the next weeks and months it will probably be able to identify what the problem is and where the problem is.

“Until the level of nutrients coming in to the lake is significantly reduced or eliminated I can see the end of Lough Carra within 10 years if the current inflow is not stopped. We can only destroy it once. I can live without the angling, even though I enjoy it, but we cannot live without the water. There are 2,000 consumers dependant on it for their water.”

In 2015, Chris and Lynda Huxley published the 180-page book, Lough Carra. In the preface they wrote: “Although Carra still retains the greater part of its ecological, environmental, aesthetic and recreational values, there is no doubt that it has, in many respects, declined in quality over the last few decades.

“In this book we hope to raise awareness of the existing problems as well as those that lurk on the horizon and, in this way, provide some basis for local people, communities and the relevant authorities to perhaps to begin to reverse the decline and restore the lake and its surroundings to the extremely high quality natural resource that it once was.”