The diversity of aquatic plant life in Lough Derg has been badly hit by declining water quality. PHOTO: ODHRAN DUCIE

Lough Derg plant species hit by pollution

The diverse water plant life of Lough Derg has been nearly wiped out by pollution, an expert has claimed, as concern mounts over the negative impact of nutrient runoff from farmlands and inadequate sewage treatment.

Many lakes are “almost destroyed” from a species mix point of view, notably Lough Leane in Co Kerry and our own Lough Derg here in north Tipperary, both of which are in a very poor state in terms of plant diversity, Dr Micheline Sheehy Skeffington commented.

Dr Sheedy Skeffington is President of the Botanical Society of Britain & Ireland (BSBI), publishers of Plant Atlas 2020, a volume documenting the findings of a detailed survey made public last week, showing a 56% decline in Ireland’s native wild plants over the past 35 years.

The report said “some lakes are now dominated by the few aquatic plants favoured by nutrient enrichment, such as the introduced nuttall’s pondweed”, a species evident in Lough Derg.

More than half of Ireland’s native plants are in decline, while many of the habitats on which Irish wild plants depend have been destroyed or changed by farming and forestry over the past seven decades, according to the findings of the 20-year study.

The study, the largest of its kind ever undertaken, alludes to what it terms “the devastating loss of Ireland’s wild plants” in particular.

The loss of diverse grassland species is most pronounced in areas of intensive agriculture, while the decline of lake and freshwater plants is largely attributable to runoff pollution such as excess phosphate and nitrates from farms, poor waste water treatment and discharges of raw sewage.

Dr Sheehy Skeffington said that in some cases, such as in lakes and rivers, the negative impact on native plant diversity due to nutrient, mud or peat runoffs may be reversible. “This can be and should addressed locally,” she said.

The Department of Agriculture needed to work more closely with the National Parks & Wildlife Service to support farmers, the custodians of our landscape, to preserve our wild habitats. Farmers understood the land better than anyone, she said, and working with them towards a results-based system was vital.


Meanwhile, the Environment Protection Agency (EPA)in a report published last year said poorly treated sewage continues to harm the quality of our rivers, lakes and coastal waters. It pointed out that just half of Ireland’s sewage was treated to the European Union standards set to protect our environment. The statistics are reflected locally with communities expressing concern about inadequate waste water treatment facilities in areas such as Ballina, Newport, Coughjordan and Ballyommon.

The EPA says water quality of our rivers, lakes, estuaries and coastal areas continues to decline. Only just half of rivers, lakes, estuaries and coastal waters were in a satisfactory condition, and ongoing decline was evident.

It’s report showed that there was just one single monitored river site in County Tipperary of high quality status.

The report indicated that of the river sites monitored in the county, 54 were of good quality, 74 were just of moderate quality and a total of 40 sites were classed as poor – second worst in the 26 counties only to Donegal which had 45 monitored river sites in the “poor” category.

The Suir and Nore rivers, which both flow through Tipperary, were among waterways listed with the highest level of ecological decline, a statistic that was also evident in the Lower Shannon catchment.

The EPA has said local authorities need to deploy and target resources more effectively in order to improve water quality and it has urged councils to increase the level of farm inspection and enforcement activity to reduce the impact of agricultural activities.