Natural Resources Wales responds to pollution incidents affecting River Kenfig

Natural Resources Wales (NRW) is investigating pollution incidents linked to infrastructure at the Marlas Sewage Pumping Station (SPS), which are impacting the River Kenfig.

The issues relate to the Marlas SPS near North Cornelly in Bridgend and its associated rising main (large pipeline) operated by Dŵr Cymru Welsh Water (DCWW).

Spanning approximately 9km, the pipeline conveys sewage to Afan Wastewater Treatment Works, but has experienced recurring bursts since August 2023, leading to multiple pollution incidents.

NRW officers have responded to these incidents, attending the sites to collect evidence, monitoring the environmental impact and then requiring DCWW to take action to address the failures.

In February 2026, the situation escalated with a continuous discharge from the Marlas SPS. As a result, DCWW commissioned a temporary sewage treatment plant at the site.

These issues have led to repeated discharges to the River Kenfig, which has had a significant impact downstream, including pollution, odour and impact on fish and other wildlife.

Following DCWW completing the installation of a temporary overland rising main on Tuesday 9 June 2026, the continuous discharge from Marlas SPS and the temporary sewage treatment plant has ceased.

While this is expected to significantly reduce the risk of further pollution, there remains the potential for additional incidents while infrastructure issues are fully resolved. NRW continues to closely monitor the situation and assess the effectiveness of the measures in place.

Huwel Manley, Head of Operations South West Wales, said:

“This issue is extremely serious. The scale of environmental impact on the River Kenfig is unacceptable, and we understand the concern and frustration this has caused for local communities, as well as the damage to wildlife and the wider environment, including Kenfig National Nature Reserve.

“We are undertaking detailed investigations into these incidents and will take the appropriate action in line with our Enforcement and Sanctions Policy.

“During our formal investigations we are unable to provide detailed information, as disclosure at this stage could risk prejudicing any enforcement outcome.

“But we want people to be assured that we are closely monitoring the situation as we build our case. Our officers are attending the site regularly to undertake important monitoring work, to continually assess the environmental impact and are ensuring DCWW delivers the necessary improvements.

“We have informed DCWW that we expect them to undertake remedial work to clean up affected stretches of the River Kenfig along with a plan for longer term enhancement of the river and its biodiversity. 

“We are also keeping the local community and partners informed, and will continue to do so via our dedicated incident webpage as more information becomes available.”

Marlas SPS operates under a water quality discharge permit, which allows the discharge of storm sewage or sewage in an emergency within specific criteria.

DCWW, which operates the site, is responsible for meeting permit conditions and managing the impact of these discharges.

NRW is undertaking detailed formal investigations, taking into consideration each incident that has occurred at these sites, including assessing environmental impacts and suspected breaches of permit conditions.

For more information, visit the Marlas Sewage Pumping Station and River Kenfig incident webpage.