An Anglo-Saxon monument that has protected status had been "degraded" by walkers and dog waste, a council said.
The Devil's Dyke earthbank in Cambridgeshire has both Site of Special Scientific Interest and has Scheduled Ancient Monument statuses.
East Cambridgeshire District Council cited it in a document aiming to get developers to create wildlife sites.
Craig Bennett, national chief executive of the Wildlife Trusts, said there was a "tension" over access and protection.
The Devil's Dyke
- a man-made defensive barrier dating from the 6th and 7th Centuries
- seven and a half miles long stretching from Reach to Woodditton and crossing the Newmarket Racecourses site
- up to 100ft high in some places
- home to many wildlife species including the rare lizard orchid flower and chalkhill blue butterfly
- one of 22 protected sites in East Cambridgeshire District Council area
- a public right of way exists along the top of the dyke
In a planning document approved last week, the council set out conditions new housing developments must meet to "protect the natural environment".
It said that at the Devil's Dyke "habitat degradation is occurring, particularly through trampling of vegetation and soil enrichment from dog excrement".
It added there were also issues with littering, fires and dogs off leads posing "a risk" to grazing livestock.
The Dyke is privately-owned, but it is managed by a partnership of landowners, Natural England, English Heritage, the Bedfordshire, Cambridgeshire & Northamptonshire Wildlife Trust, and Cambridgeshire County Council.
Mr Bennett, who lives in Cambridgeshire, said it was "important we build understanding about what are right ways to behave on these very precious nature sites".
Many sites run by the Wildlife Trust have signage and some have staff "engaging" with the public, but it had "been difficult" recently due to staff being furloughed, he said.
He added that "ultimately we need more space for nature", which would reduce numbers visiting protected sites.
East Cambridgeshire District Council said new developments of more than 150 homes should create or fund a "new rich wildlife habitat" either on the development or at another site.
It said these off-site areas should be "adjacent to strategically important biodiversity areas" such as the Devil's Dyke.
Councillor David Brown said the authority was making sure new developments "both protect the natural environment and create new areas for wildlife to thrive".