The Environmental Protection Agency has revealed a 90 per cent compliance rate with the phosphorus Environmental Quality Standards – a key chemical indicator of water quality – across the west.
The EPA this week published three Integrated Water Quality Assessments for 2013 and nationally, these assessments showed that 60% of rivers and lakes in Ireland achieved a High standard of compliance with the phosphorus Environmental Quality Standards.
By contrast, more than 90% of rivers and lakes, in the Western River Basin District display a High compliance with these standards.
Only Clarinbridge and Kilcolgan Rivers in Galway, Ballindine River in Mayo and Tubbercurry River in Sligo displayed ‘less than good’ compliance with the standards.
In the assessment period 2011–2013, Connemara’s Aughrusbeg and Tully lakes improved from moderate to good compliance with key chemical quality standards – including phosphorus – and Nambrackmore Lake improved from good to high.
Carrowmore Lake in Mayo, which is an important angling amenity and drinking water source, declined from good to moderate compliance with these quality standards due to elevated phosphorus results. Loughs Corrib, Mask, Cara and Cullin continued to show a high level of compliance with these standards.
The Western River Basin District is made up of 89 water catchments or drainage systems, includes counties Mayo and Sligo, a proportion of Galway and small parts of Roscommon and Clare.
The main cause of water pollution in the Western River Basin District is nutrient enrichment, caused by an excess of phosphorus and nitrogen inputs.
Analysis of long-term trends, indicate that concentrations of phosphorus in all Irish water bodies (including those in the west) have been decreasing since the late 1990s.
In spite of this, only 80% of river channels in the western region displayed a good or better biological classification in the most recent assessments (2011–2013), with only 27% achieving a high classification. Continued reduction in concentrations of phosphorus and nitrogen should result in improved biological classification of these water bodies.
Agricultural pollution (31%) and waste water discharges (26%) were the main causes of river monitoring stations failing to achieve at least Good biological classification in the Western River Basin District.
Commenting on the Western River Basin District Integrated Water Quality Assessment results, said:
“Phosphorus concentration is a key indicator of health for a lake, river, estuary or groundwater,” explained EPA chemist Alan Stephens.
“There is wide regional variation in concentrations of phosphorus in rivers and lakes due mainly to historic agricultural practices. The availability and assessment of up to-date monitoring data and long-term trends will be crucial to identifying, protecting and managing the remediation of vulnerable water bodies.
“Phosphorus inputs to water bodies should continue to be reduced. Changes in practices are required to improve and protect water quality.
Improved compliance with the Nitrates Directive to reduce agricultural pollution will be needed as well as improvements in waste water infrastructure and operational practices,” he added.