Biologist fears Lough Derg water move poses risks

CONCERN about the proposed extraction of 500 million litres daily of water from Lough Derg during prolonged periods of low-flow and drought has been expressed by a north Tipperary marine biologist.

Dublin City Council is seeking permission to pump raw water during high flow and flooding periods from northern Lough Derg into large-scale storage lakes in Offaly for the Dublin region.

But local campaigners fear this will be extended to low-flow as the population in the city is projected to increase to 2.2 million by 2031.

Dan Minchin of the Lough Derg Science Group says the group didn’t have enough scientific information to ensure the proposed abstraction would not affect the Lough Derg ecosystem.

Dr Minchin, who lives on the shores of the lake, explained that water flow and circulation throughout the lough was important for its health.

During dry periods the surface water heats up and, being lighter, separates from the colder and heavier water beneath.

Already in the late spring and early summer, lake users have witnessed such trends with differences of up to 8ºC between the warm and deeper cold layers.

The colder water zone gradually loses its oxygen and if these conditions persist the oxygen gets used up and fish and their food could die unless this water gets re-circulated.

“The option to abstract water at the Parteen Dam, at the lower end of Lough Derg, would at least enable the water to pass through the lake before being removed and this option should be revisited,” he said.

Dr Minchin is unsure that such an abstraction plan is necessary.