POLLUTION LEVELS in rivers and streams in Ireland have risen dramatically in the last two decades as a result of increased housing development and intensive agriculture and forestry.
Water quality at wells and springs, which are the source of a quarter of drinking water supplies, has also declined due to contamination by animal and human faeces, a major new study shows.
Water Quality in Ireland 2007- 2008 shows the percentage of rivers considered to be “high-quality sites” – or largely pollution-free – has fallen to 17 per cent in 2006-2008, down from 30 per cent in the period 1987-1990.
The biggest percentage decline in “high-quality sites” was experienced in the northwestern Neagh-Bann and Shannon regions.
The largest numbers of largely pollution-free sites are in less densely populated and less intensively farmed parts of the country, typically the southwest and west.
The report, which was published yesterday by the Environmental Protection Agency (EPA), concludes the dramatic reduction in water quality has been caused by nutrient inputs, siltation and acidification as a result of forestry, agriculture and housing.
It says “high-quality sites” are important to support aquatic species that are sensitive to siltation and pollution, such as freshwater mussels and juvenile salmon, which are both in decline.
Dr Jim Bowman, programme manager of the aquatic environment programme at the EPA, said the key contributor to pollution levels was municipal and agricultural discharges.
“The dramatic decline in the number of high ecological quality river sites during the past 20 years, largely due to low-level enrichment and siltation in upland areas, is unacceptable and will have to be addressed,” Mr Bowman said, adding that it would be a huge challenge to protect the remaining “high-quality sites” and restore those that had degraded.
The report analyses water quality in 13,200km of rivers and streams, 433 lakes, 89 tidal water bodies and 275 groundwater sources.
It found a slight decline in the quality of water in lakes in the period 2006-2008 when compared with a previous EPA assessment in 2004-2006.
There were 34 fish kills reported in 2008, up from 22 in 2007. Most of the kills are associated with local authority operations and agricultural activities. The reports notes this is lower than in the period 2004-2006, but says it is still unacceptably high as each fish kill is a “catastrophic disturbance” for aquatic life.
It says overall water quality in the Royal and Grand canals in 2006-2008 was good, which is a similar finding to the last EPA study in 2004-2006.
It found water quality had improved in the estuarine and coastal sites that it monitors, and that Irish shellfish-growing waters were typically of a “high quality”.
However, the EPA’s analysis of groundwater (wells and springs), which accounts for 26 per cent of drinking water supplies here, highlighted an increase in pollution levels in 2006-2008, when compared with 2004-2006.
It found 67 per cent of groundwater sites had faecal conforms, which are caused by animal and human faeces. This is a 10 percentage point rise from the 2004-2006 EPA water study.
The number of bathing waters complying with the EU minimum requirements regarding pollution levels fell in 2008 when compared with 2007. Some 93 per cent of bathing sites met the EU requirement, a drop of four percentage points from the previous year.
Polluted: worst affected
Seriously polluted stretches of water in 2008
Arigna (Roscommon)
Ahavarraga stream (Limerick)
Aughboy (Wexford)
Avoca (Wicklow)
Borrisoleigh (Tipperary)
Bredagh (Donegal)
Brosna (Westmeath)
Clarinbridge (Galway)
Dunshaughlin stream (Meath)
Jiggy (Roscommon)
Lee (Kerry)
Owengar (Leitrim)
Roechrow (Donegal)
Roosky (Roscommon)
Shinrone stream (Offaly)
Swilly Burn (Donegal)
Tubbercurry (Sligo)
Tubercurry stream (Sligo)
Tully stream (Kildare)
Source: EPA