Several major housing projects in Kent can now go-ahead - but only if developers build their own expensive on-site sewage treatment works.

It is part of the solution councils have been working on following an environmental bombshell involving the Stodmarsh nature reserve, near Canterbury.

Natural England called for planned construction to stop after the discovery of high levels of nitrogen and phosphorous pollution caused by waste water entering the reserve’s lakes, which are fed by the River Stour.

It sent shockwaves through the construction industry and has stalled progress in building of tens of thousands of much-needed homes across east Kent.

Among the developments put on hold around Canterbury are the 4,000-home Mountfield Park scheme south of the city, 1,100 homes at Sturry and Broad Oak, and the redevelopment of the Nasons and Debenhams sites in the city centre.

In Ashford, construction of the controversial 725-home Conningbrook Park, or 'Large Burton', estate has been delayed, as well as the redevelopment of the former Kent Wool Growers site in Tannery Lane.

Both Canterbury City Council and Ashford Borough Council have been working with Natural England on solutions to mitigate the impact on the nature reserve.

They include the creation of additional wetlands - although it is not clear where they will be located or how long this would take.

This week the city council said planning permission had now been granted to Corinthian Land for Mountfield Park to start, with conditions including an on-site sewage treatment works.

City council spokesman Rob Davies says the building of new homes and the possible detrimental effects that could ultimately have on water quality and wildlife is becoming a nationwide issue.

He says six east Kent councils have written to the housing secretary and environment secretary asking for help and support in tackling delays to “desperately-needed housing”.

“The danger of nitrates and phosphorus entering the watercourse has meant we have faced delays in granting planning permission for desperately-needed housing,” he added.

“Improvements to the sewerage infrastructure system such as investment in Southern Water’s Canterbury waste water treatment works in Sturry is one key route to solving this problem but that lies outside the control of the councils involved and will take time,” Mr Davies added.

“In the meantime, we have found some answers locally that have allowed us to start granting planning permission again for some of our largest strategic sites such as the creation of wetlands to offset the nutrients entering the system, such as reed beds and localised waste water treatment works built by developers.

“We are working hard in the background with our neighbours to find acceptable ways of unlocking smaller housing developments right across the district as quickly as we can.”

Corinthian Land declined to comment.

The Nasons and Debenhams sites in Canterbury have permission for 135 flats.

Karl Elliott of Clague Architects, which is involved in both projects, said: “Everyone we talk to, including the local authority, says it’s ongoing, and everything is still on hold.

“We have been hearing of a multi-layered solution of ‘off-set’ land to create wetlands. But it will mean funding from developers, who will have to put their hands deeper into their pockets.

“It goes back to one prediction that it could be years before it’s sorted.”

Mr Elliott said he was getting calls daily from clients and interested parties asking “what the hell is going on?”

He added: “The owner of Debenhams has a buyer for the annexe building in Guildhall Street which has planning approval but they won’t buy it until Stodmarsh is sorted.”

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