The European Commission has begun legal proceedings against the Republic in nine cases involving breaches of EU environmental law.
The alleged infringements include unlawful waste operations, the pollution of shellfish waters by urban waste and failure to protect rare birds and sea mammals, such as dolphins.
In two cases, the Republic has been condemned by the European Court of Justice, but the Commission says that the Government's response to the court rulings has been inadequate.
The Environment Commissioner, Ms Margot Wallström, said that failure to apply EU law meant that Irish citizens were not receiving the level of environmental protection to which they were entitled.
"One important objective of EU environmental law is to protect Europe's biodiversity. Ireland's nature is stunningly beautiful. It is important to preserve this richness for future generations, as well as for the tourists that visit Ireland. Full implementation of EU conservation legislation will ensure this. Ireland also has to continue to fight against illegal waste operations, and clean up the damage they have created to give its citizens the quality of life they have the right to expect," she said.
The Commission accuses the Government of failing to respect EU directives that protect wild birds and wildlife habitats by failing to prevent over-grazing by sheep in sensitive areas.
In response to a European court ruling two years ago, the Government took steps to reduce sheep numbers in places such as the Owenduff-Nephin Beg complex, a 25,000-hectare area of blanket bog, mountains, rivers, springs and lakes in Co Mayo that constitutes the State's largest special protection area for birds.
The plans have not been fully implemented, however, and the Commission complains that binding legal requirements to prevent habitat damage in the Owenduff-Nephin Beg Complex have not been introduced.
Another case concerns "wide exemptions for damage and disturbance caused by farming and other activities" in Irish environmental legislation that inhibit the proper protection of a number of species, including the horseshoe bat, the natterjack toad and dolphins and whales.
The Commission has also referred Ireland to the European court for failing to control the use of quad-bikes and jet skis in environmentally-sensitive areas.
A court ruled last year that the Government had to establish pollution-reduction programmes for the 14 areas along the Irish coast designated by the EU as shellfish waters. The Commission says, however, that proposed measures to prevent the pollution of such waters by untreated urban waste, which can cause harmful microbes, do not go far enough.
The Minister for the Environment, Mr Cullen, promised to co-operate with the Commission in implementing environmental rules but insisted that Ireland's record was a good one.
"Ireland is 98.8 per cent compliant with EU law. This puts Ireland as fourth best out of the 25 members. Yes, there are matters outstanding and the Government is proactively working with the Commission to deal with these. Just as with all member-states, challenges will occasionally arise.
"An illustration of this is the difficulties Europe faces in dealing with illegal movements of waste. But deal with it we must and deal with it we will," he said.
EU treaties give the Commission power to act against member-states for breaches of EU environmental law, which can lead to financial penalties imposed by the European Court of Justice.