The Office for Environmental Protection (OEP) is to conclude its investigation into the regulation of combined sewer overflows after securing significant progress in tackling the issues it has raised.

Through its investigation the OEP found that there have been failures to comply with environmental law by the Department for Environment, Food and Rural Affairs (Defra), the Environment Agency (EA) and Ofwat relating to the regulation of network CSOs.

Helen Venn, the OEP’s Chief Regulatory Officer, said: “It is clear through the report of the Independent Water Commission published earlier this week and the government response that there is a need and an appetite to improve how the water sector operates to protect the environment. Significant reforms are on the way.

“While there are no quick fixes, we are confident that as a result of our investigation, future reforms relating to regulation of untreated sewage discharges can be based on a clearer understanding of what the law requires and the current roles and responsibilities of the different authorities.

“The decision notices we issued in December formally clarified the actions we required to be taken by the public authorities to rectify failures. Many of those actions have now been taken, are being progressed, or commitments are in place to do so. Significant progress has been made.

“While this means it is right that we conclude the investigation at this time and there is no need to proceed to court action, we will continue to monitor to ensure the actions committed to but not yet taken are progressed.”

“As a result of the OEP’s investigation, there is now clarity that the regulatory system should only allow untreated sewage discharges to take place in exceptional circumstances, unless the cost of preventing or mitigating them would be excessive.

“There is also improved clarity over the roles and responsibilities of the different bodies in overseeing this complex system and we have seen a stepping up of required regulatory activity, such as Ofwat’s recently concluded investigations resulting in enforcement action against three companies.

“Over the course of the investigation we have seen a considerable increase in the responsible public authorities’ focus on this issue. This has revealed the scale of the issues which they are now taking action to address. These actions will contribute to improvements and mean that future reforms to the water sector will be built on firm legal foundations.”

Steps taken by the authorities in response to the OEP’s recommendations include:

• Defra has replaced outdated guidance with a new policy and guidance document that better reflects the legal duties of sewerage undertakers.
• Ofwat has revised its enforcement guidance and taken enforcement action against several water companies.
• The Environment Agency has updated its Storm Overflow Assessment Framework and is progressing with plans to modernise permits and introduce spill limits.

Progress has also been demonstrated on cross-cutting issues, such as the clarification of roles and responsibilities between the authorities and improvements to the assessment of cost-effective solutions for reducing CSO discharges.

The OEP will publish detailed reports on the investigation in the autumn. The investigation was launched in response to a complaint received by Salmon & Trout Conservation UK, now known as WildFish.