The European commission is taking the UK to court over infringements of directives covering large power plants and wastewater.
The first infringement relates to the Aberthaw coal-fired power plant in Wales, which has exceeded the limits on emissions of nitrogen oxides (NOx) under the large combustion plant Directive (LCPD).
The commission says the permit for the power station sets a ceiling on NOx emissions that is much higher than is allowed under the LCPD - 1200 mg/Nm3 compared with 500 mg/Nm3. The commission first raised its concerns in a letter to the government in June 2013, followed by a reasoned opinion in October 2014.
Although the commission acknowledges that the UK has been working to resolve the issue, it has now decided to take legal action. In statement, the commission said it welcomed recent indications from the UK authorities that investments will be made to upgrade the plant, but noted that the plant continues to operate under a permit which allows it to emit high levels of the toxic gas NOx. "The commission is therefore referring this case to court," it said.
A spokesperson for Defra said: "We are tackling emissions from industrial sources by setting stringent limits for industrial installations, including coal power stations. Aberthaw power station is also investing to meet future emission limits set by the EU. It would be inappropriate to comment on this case further while infraction proceedings are underway."
The commission has also started legal proceedings against the UK for infringing the urban wastewater treatment Directive in 17 locations across England, Wales, Scotland and Northern Ireland.
The Directive requires countries to ensure wastewater discharging from urban areas into undesignated waters is adequately treated.
Deadlines for meeting the Directive ranged between 1998 and 2005, depending on the size of the urban area the wastewater was coming from and the sensitivity of the water it was being discharged to.
Four areas including Banchory and Stranraer in Scotland have inadequate treatment for wastewater, while another ten including Tiverton and Chelmsford in England fail to meet the higher standards set by the Directive for sensitive waters such as estuaries, according to the commission. Gibraltar, which the commission says has no treatment plant at all, is also included.
The infringement also covers excessive spills from stormwater overflows in collecting systems serving Llanelli and Gowerton in Wales.
The commission said in a statement: "Innovative and environmentally positive sustainable urban drainage solutions are now being implemented to improve the situation. However, the current spill rates are still too high and compliance is not foreseen before 2020."
A Defra spokesperson said: "It is encouraging that 98% of wastewater plants are now a good standard and we are working hard to improve the rest.
"Working with water companies, we have secured around £13.5 billion to improve infrastructure and are confident that we will be able to make the necessary improvements to get all treatment plants up to the EU standard by 2016," she said.