The Environment Agency is continuing to monitor a section of the River Dee in Chester following a “pollution incident” there last week.
The problems began when sewage spilled into the river from a burst pipe at Welsh Water's Chester treatment works last Wednesday.
Wet weather then compounded the issue, increasing the amount of sewage that had to be dealt with at the site, so Welsh Water had to “release partially treated and diluted wastewater” into the River Dee to avoid any problems with the wider sewer network.
An Environment Agency spokesperson said: “Our officers were involved in the response to the sewage pollution incident in the River Dee, which began on Wednesday, October 4.
“The source of the pollution was stopped in the early hours of October 5, and is no longer affecting the river.
“The Environment Agency has worked closely with our partners throughout the incident to resolve the problem and minimise any environmental impacts.
“We are continuing to monitor the area for potential effects on the local environment.”
Natural Resources Wales were also informed of the incident.
Steve Wilson, managing director of Welsh Water’s wastewater services, explained: “We are currently investing £6.9 million to improve how we treat wastewater in Chester. Unfortunately, during this work, a pipe burst at our Chester wastewater treatment works and we worked through the night to complete the repair.
“The wet weather led to an increase the amount of wastewater we had to deal with at the site. This, as well as the location of the burst pipe, meant that we had to release partially treated and diluted wastewater into the River Dee. This helped us to avoid any further problems which could have impacted on the wider sewer network.”
Mr Wilson apologised for the incident, adding: “While no services to customers were affected by this burst, we are extremely sorry that this has happened. We notified both the Environment Agency and Natural Resources Wales and will continue to investigate and work closely with them to minimise any potential impact this may have on the surrounding area.”
Residents from Wirral were asked to avoid contact with the water along the Dee coastline last week.
A spokesman for Wirral Council said: “Environmental Health officers in Wirral are satisfied that the waters in the River Dee along the west Wirral coast are safe after an incident in Chester saw a release of waste water into the River Dee.”
See full story in the Chester Leader