Officials at the agency are currently reviewing the Grimston site, which is located east of King's Lynn about 600 metres upstream from Derby Fen - a Site of Special Scientific Interest.

It followed campaigners who are calling for better protection of the Gaywood River, which the storm overflow releases into, conducting tests which they say found high levels of pollutants at the nature site.

An aerial photo of the Grimston sewage works (Image: Gaywood River Revival)

Tests conducted last month by Gaywood River Revival found high levels of E.Coli at Derby Fen, a bacteria which comes from human and animal waste.

An Environment Agency spokesman said: "Protecting water quality and the environment is a priority.

"It is completely unacceptable that so much sewage is still entering our waterways and it cannot........

© Eastern Daily Press