Six of Ireland’s rivers are badly polluted, the Environmental Protection Agency has warned.
It also revealed that the number of pristine waterways in the country fell to 21 in 2015 - down from 38 in 2009 and 500 in the late 1980s.
In its first six-year review of water quality under new European rules, the EPA warned that Ireland has failed to meet its clean-up targets.
Six rivers were classed as badly polluted.
They were the Tolka between Clonee and Clonsilla in Dublin; the Avoca in Co Wicklow; the Aughboy in Co Wexford; the Bredagh near Moville in Co Donegal; the Laurencetown stream in Co Galway; and the Srah river which runs into Lough Mask near Tourmakeady in Co Mayo.
The review showed some improvements in water quality as 19 rivers were classed as badly polluted in the 2007-2009 period.
Matt Craig, senior scientific officer with the EPA, said: “It would be a huge concern in terms of the approaches that we have taken so far aren’t doing enough.
“We need to be targeting different protective measures in different areas.”
The report is compiled as part of Ireland’s commitments under the European Water Framework Directive. It does not provide evidence for the deterioration of standards in some areas.
EPA specialists highlighted issues with waste water run-off, treatment plants, floods, one-off house building, clear felling of forestry and agriculture.
The report also noted an increase in the number of reported fish kills, with 97 reported between 2013 and 2015, up 27 on the 2007-2009 period.
It said the reason is unclear but it may be due to extended dry spells and/or flooding events rather than increasing serious pollution spills that would have been the main cause of fish kills in the past.
Andy Fanning, of the EPA’s evidence and assessment section, said raw sewage was being discharged in more than 40 locations around the State.
“We have locations in the country where there is absolutely no treatment (of water). . . which is not acceptable,” he told Newstalk Breakfast.
Targets set since 2010 to meet an improvement in water status of 13 per cent have not been met, he said, adding that “we’ve actually ended up with a very static situation where our water policy stayed exactly where it was at the beginning”.
EPA has joined forces with Irish Water to identify and address areas that are impacting on the ecology, Mr Fanning said. “But we will need a very sustained level of investment to improve the systems that we currently have,” he said, adding that the State would have to provide “substantial funding”.
The review says hundreds of water bodies around the country failed the water quality tests, cancelling out the improvements in water status at a similar number of water bodies in other parts of the country.
Overall, 91 per ent of groundwater bodies, 57 per cent of rivers, 46 per cent of lakes, 31 per cent of estuaries and 79 per cent of coastal waters were found to be of good quality under the EU directive.
Earlier this year the European Commission said it was taking Ireland to court after repeated warnings over the pumping of raw sewage into rivers and the sea.
It said more than 30 towns and cities have inadequate treatment plants for waste water, putting human health at risk, and leaving the country potentially liable for millions of euros in anti-pollution fines.