A high street department store could stand empty and derelict for years because of water pollution in protected lakes five miles away.

Ambitious plans to transform the former Nasons building in Canterbury into a mix of shops, cafes and flats have ground to a halt over a complex environmental issue stalling thousands of homes across east Kent.

It is a major setback to the already struggling high street, with the issue also delaying aspects of the Debenhams regeneration.

The problem, say environmental experts, is that residential developments are creating water pollution at the internationally recognised Stodmarsh Nature Reserve on the edge of Canterbury.

The concerns were first raised last year by Natural England, which is warning that the Stodmarsh lakes - a haven for protected wildlife - are being contaminated by waste water discharges from existing housing developments filtering into the River Stour catchment area.

It says there is “sound evidence" these nutrients are causing eutrophication - a process which causes pollution and promotes excessive algae growth.

The studies have had major repercussions on housing developments across all areas near the Stour in east Kent, which stretches to Ashford, towards Thanet and down to Folkestone.

Natural England fears that by allowing more homes to be built, the pollution levels will increase unless approved mitigation measures - like on-site sewage treatment plants - are included in housing schemes.

The issue is said to be holding up the development of thousands of homes across east Kent, including those within the Nasons and Debenhams projects

Architect Karl Elliot, who is managing partner of Clague and involved in both projects, says the new homes will not be built until 2023 at the earliest, but "likely much longer."

"These two sites alone could provide up to 150 much-needed homes on what are brownfied sites in the city centre," he said.

But the situation is worse for the planned redevelopment of Nasons because its retail and residential proposals are so closely integrated, with one unable to go ahead without the other.

"We have been acutely aware of this situation for many months and have been promised solutions and updates over the same period from the planning team, but to no avail," said a frustrated Mr Elliott

"As such, developments such as Biggleston Yard at the former Nasons, and Debenhams in Canterbury, are unlikely to be able to be progressed until 2023, at the earliest."

Canterbury City Council has been warned by Natural England it must not grant plans for housing unless there are measures included to mitigate the pollution effect.

The issue has put the whole £30 million Nasons redevelopment plans on the backburner and will delay the 74 flats proposed for the upper floors of the former Debenhams.

It is a huge blow to the city centre, where a combined £55 million of private investment has been pledged at a time when Canterbury's economic fortunes and city centre economy are in need of a boost.

Canterbury Business Improvement District boss Lisa Carlson says the delays are disappointing, but she hopes the timescale suggested by Mr Elliott is pessimistic.

"The Stodmarsh problem is significant for the whole of east Kent and it's important for all of us to keep pushing for a solution," she said.

"We have to consider that the timescale laid out for Nasons is a worst-case scenario.

"We just need to keep the pressure on because we need to see some progression in the middle of the high street.

"But the news about Debenhams is more encouraging, and we have other empty shops which are under offer."

We need developers to keep belief in Canterbury

City council leader Ben Fitter-Harding has called for a quick solution to an issue hampering housebuilding across the district and the delivery of the Nasons and Debenhams schemes.

"These are hugely important regeneration projects for Canterbury, and it's galling that private investment coming into the city is being stalled over a issue we have no direct control over, which is now having an impact on its delivery," he said.

"We are working closely with various agencies, including Natural England, other councils and the Government to push forward solutions to this, and talks are ongoing, but there's no quick answer to it, unfortunately.

"We are doing everything we can, and our head of planning is leading the effort. I would call on Natural England and the Government to provide all the support necessary.

"Because, as a result, we can't deliver our housing targets or the economic growth needed coming out of the pandemic.

"Someone, somewhere, will have to actually put their money where their mouth is and sort this out.

"Providing waste water treatment on the sites of developments may be possible in some cases, but not for the Debenhams and Nasons schemes, I suspect.

"But we need those developers to keep their belief that Canterbury is the right place to invest, and they will stick with us and work with us."

Lisa Carlson from Canterbury Business Improvement District

They promised so much

Not since Whitefriars was built has the city centre been promised such ambitious redevelopments as those presented for the former Debenhams and Nasons department stores.

Opposite each other in the high street, they are both key retail locations with extraordinary potential, seized upon by architects.

For Debenhams, new owners 90 North Real Estate, which is chaired by former Dragon's Den investor James Caan, says it is a prime site with 100,000 sq ft of space over four floors and across three separate buildings.

Architects came up with an eye-catching £25 million mixed scheme - rebranded the Guildhall Quarter - for 12 retail units and 72 apartments on the upper floors.

It was widely approved of and gained planning permission at the start of 2020.

The planned £30 million redevelopment of the Nasons site - now owned by the Setha Group - is arguably bolder, opening up the site and creating a food hall, a retail arcade and cafes, as well as 38 flats and 28 serviced apartments.

In a nod to its history, the site has been rebranded Biggleston Yard.

Architects were in the process of tweaking the design, following a public consultation, and had been expected to submit a planning application, which is now not forthcoming.

Reasons to be cheerful

A new name will be coming to Canterbury and setting up shop in the former Debenhams.

Because while the development of the flats on the upper floors is being stalled, there is excitement about what is being created on the lower floors.

The company behind the promising new venture is 15:17 which is planning to open one of its chain of Fresh, Local and Wild food and produce stores and is inviting local artisan suppliers to get involved.

It also sells gifts, homeware and a mix of 40% local and 60% regional and national produce, which will also supply its cafe.

But 15:17, which has taken 80,000 sq ft of space on three floors of the former department store, is also planning to being some vibrant new retail names and interactive experiences to Canterbury.

The store will be one of 22 openings the company is planning across the country this year.

On its website it says: "We believe our brand is positioned alongside Waitrose and M&S Food on the high streets and within the market place.

"We're obsessed with finding beautiful local produce and treasures, whether that's potatoes or pashminas - tea or teddy bears.

"We're passionate about the high street and championing local enterprise, so what better than to bring all this together in a place convenient for all?

"We're supporting local businesses, with a select few national and international brands allowing us to offer the latest trends in fashion, beauty and home at an affordable price.

"Our aim is to bring the fun and colour back to retail, whilst doing a bit of good along the way."

It is hoped that if works can progress on schedule, the store could open in June.

Why Stodmarsh Nature Reserve must be protected

Natural England says Stodmarsh Nature Reserve, which covers a square mile, has been protected and managed for nature conservation for more than 40 years.

It has internationally-important reed beds, fens, ditches, wet grassland and open water, which provide an ideal habitat for breeding and wintering birds, invertebrates and rare plants.

This site is especially important for bittern, marsh harriers and the shining ramshorn snail, which are rare across Europe, as well as water voles, which are rare in England.

The reed beds are also an excellent sanctuary for migrating birds such as swallows and house martins in the summer, and starlings in the winter. Kingfisher, great crested grebe, coot, moorhen, reed bunting, bearded reedling can also all be seen.

The site supports a large variety of invertebrates, including dragonflies and moths, and rare plants.

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