Officers from Natural Resources Wales (NRW) are attending an incident in Caldicot involving a fractured sewage pipe.
NRW officers are currently assessing the environmental impact and working with Dŵr Cymru Welsh Water to advise on how to protect sensitive areas nearby.
These include the Gwent levels, a Site of Special Scientific Interest and the Severn Estuary, a Special Area of Conservation.
Dŵr Cymru Welsh Water has responded quickly to the incident and are working to repair the pipe. This includes tankering away material from a sewage pumping station in the area.
Emergency storm outlets are also being used to manage the flows of diluted sewage. Dŵr Cymru Welsh Water is permitted to do this in emergencies.
Holly Sisley, Natural Resources Management Team Leader said:
“We’re monitoring the operation here to make sure that everything possible is being done to minimise the impact of this incident on the local environment.
“We’ll be keeping a close eye on water quality in the area and will remain on site until we’re confident that the pipe has been repaired.
“Anyone walking on the coast path which runs along the Severn Estuary should be aware that repair works are happening close to the footpath and there may be odour and traces of sewage visible for a short stretch.
“The emergency discharges into the Estuary will occur throughout today while we continue to work with Dŵr Cymru Welsh Water to rectify the situation.”
To report concerns about pollution phone to Natural Resources Wales incident hotline on 0300 065 3000.