The drive to build hundreds of new homes across Norfolk has been halted - amid growing concerns about pollution to the Broads and River Wensum.

Government advisor Natural England has informed Norfolk councils they must not grant planning permission for any schemes involving 'overnight accommodation', until it can prove they would not lead to more nutrients flowing into waterways.

This means schemes for new houses, student homes, care homes and campsites, cannot go-ahead until measures are put in place to prevent pollution.

And, in the absence of being able to do that yet, councils have suspended granting of permission within catchment areas of the Wensum and the Broads.

Schemes that already have approval can still be built.

Every council in Norfolk - and the Broads Authority - has been affected, to varying degrees, by Natural England's announcement.

In Norwich, the city council says it means no fresh planning applications for housing can currently be approved anywhere within the city's boundaries, because the entire district is in the catchment area of the Broads and the Wensum.

Potentially, that could affect the granting of permission for a number of major applications, at a time when new and affordable housing is badly needed.

For instance, plans are due to be lodged for the revamp of Anglia Square, including more than 1,000 homes.

In Great Yarmouth, North Norfolk, South Norfolk, Broadland and Breckland, decisions cannot be taken on plans involving overnight accommodation in areas within catchment areas of the River Wensum and/or the Broads.

Even as far afield as West Norfolk, some areas are affected - around Docking, East Rudham and Great Massingham.

There is currently no timescale on how soon the issue will be resolved to allow schemes to be approved.

Natural England has taken action because, when nitrogen and phosphate nutrients enter water systems it can cause excessive growth of algae - known as eutrophication.

That pollution, generally from sewage treatment, septic tanks, farming and industry, reduces the oxygen in the water and makes it harder for aquatic species to survive.

Wastewater from new developments can exacerbate the issue.

So Natural England wrote to councils telling them they need to make assessments and, where necessary, come up with mitigation to make developments nutrient neutral.

A spokesman for Norwich City Council said: "This has put a temporary halt on our ability to grant planning permission for many types of development.

“This is a national issue with a total of 74 local councils affected by the issue of nutrient neutrality.

“We are working hard with Natural England and the other affected Norfolk planning authorities to resolve the matter as quickly as possible."

Melanie Hughes, director of sustainable development at Natural England, said the body would help councils make the assessments and come up with mitigation.

She said: "Many mitigation measures will involve the creation of new wetlands, woodland or grasslands - providing new spaces for nature and recreation in the process - or installing environmentally-friendly sustainable drainage systems.

"We recognise that nutrient neutrality won’t be easy to adopt in many cases."

The government is offering £100,000 to councils in each catchment area affected, to pay for catchment officers.

John Toye, North Norfolk District Council's portfolio holder for planning and enforcement, said: "The implementation of the changes and their effect on planning delivery are yet to be fully understood.

"We will, by working with neighbouring authorities, find solutions and support applicants with guidance on the new requirements."

Jan Davis, Broadland Green Party spokesperson and Broadland District councillor, welcomed the guidance.

He said it would help protect the Broads from algal blooms and any delay to planning applications was a "small price to pay".

He said: "Action on this complex issue is well overdue. It is therefore heartening to see Natural England taking a proactive stance by issuing guidance to local planning authorities and developers on this important issue.

"This is particularly important in the Broads where water quality is vital for our water supplies, fisheries, wildlife, and tourism."

In 2019/20, just over 4,000 homes were built in Norfolk, but that fell to about 3,250 the following year.

Could this change where homes are built?

The letter from Natural England seemed to take the majority of Norfolk councils by surprise - and left them scrambling to figure out the implications.

It is unclear how long it will take to get the processes to allow nutrient neutrality assessments - and mitigation where needed - in place.

And could this change where developers apply to build homes?

Iain Hill, a partner at Norwich-based property consultants Bidwells, thinks it might if the delays mean councils cannot prove they have a five-year housing supply.

He said: "If these targets are adversely affected, it seems likely developers will focus their attention on those settlements in Norfolk outside the identified catchment area of the habitat sites, given the certainty in relation to the decision making process they provide and their need to continue to deliver housing."