A major question mark hangs over a blueprint which is supposed to shape where 50,000 homes could be built in and around Norwich over the next 15 years.
Council leaders fear there could be delays to getting the Greater Norwich Local Plan - which outlines where development could be acceptable in Norwich, South Norfolk and Broadland - approved because of concerns over water pollution.
Natural England last month told Norfolk’s councils they cannot grant planning permission for any schemes involving 'overnight accommodation', until they can prove developments in catchment areas would not lead to phosphates and other nutrients flowing into the River Wensum and the Broads.
Natural England said too many nutrients can lead to excessive growth of algae, reducing the oxygen in the water and making it harder for aquatic species to survive.
That left councils seeking legal advice as they tried to find a way forward - and warnings of housing chaos from Richard Bacon, South Norfolk Conservative MP.
Planning inspectors who will decide whether to recommend the Greater Norwich Local Plan for approval have now also raised concerns over what the implications could be.
The Greater Norwich Local Plan details the areas the three councils - which work collectively as the Greater Norwich Development Partnership (GNDP) - would allocate for housing.
Inclusion in the plan makes it more likely planning applications in those places would get the go-ahead, while it gives councils more power to reject them in areas not covered by the plan.
But, in the light of the directive, inspectors Mike Worden and Thomas Hatfield, have written to the partnership seeking its views on what the impact on the plan could be.
Norwich City Council officers have expressed concerns it could lead to delays in getting the plan adopted.
A spokesman for the GNDP said the partnership would be responding to the letter from inspectors by the deadline of this Friday (April 29).
Some 5,000 of the homes included in the plan have already been built and locations of about 74pc already identified in previous plans.
But the latest version of it needs to allocate locations for the rest of the housing.
The plan includes 12,000 new homes in Norwich and hundreds more in places such as Hellesdon, Drayton, Taverham and Thorpe St Andrew.
There would also be 13,505 homes to the north-east of Norwich in the Rackheath area.
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