However, officers said Whaley Bridge residents who have been evacuated from their homes near Toddbrook Reservoir would be allowed to return briefly, in a ‘controlled’ way, to collect ‘vital’ belongings and pets which had been left behind.
It is not yet known when they will be able to return for good, and police repeated their advice for people to stay away from the Derbyshire town for their own safety.
At a press conference this evening, Assistant Chief Constable Kem Mehmet, of Derbyshire Police, said there was still ‘a substantial threat to life’ if the dam wall fails.
"We would ask residents to continue to heed police advice and stay away from Whaley Bridge," he told reporters.
Due to concerns raised by residents over pets being left behind, he said officials had made the ‘difficult’ decision to allow people to return to their homes in a ‘controlled’ way.
"We will be putting plans in place for residents to return to their home to pick up very vital things they need along with their animal welfare,” he said.
"This is very controlled, I must stress that, because this is still life at risk."
Mr Mehmet said emergency crews had lowered the water level by half a metre by using pumps but the structural integrity of the dam wall was still at a ‘critical level’ following torrential downpours.
He added that more pumps were being drafted in to help reduce the flow of water.
Julie Sharman, chief operating officer for the Canal & River Trust, told the press conference the water level still needs to be reduced by ‘several more’ metres.
Residents will be restricted on how long they would be able to spend at their homes after returning to collect essentials, police said.
"Plans are being put together at the minute, you'll know we have a physical presence around that area where we don't want people to enter," Mr Mehmet told reporters.
"It'll be very controlled. We'll be recording who enters, we'll be restricting that to one person per household and we'll be giving clear instructions on how long residents have got before they report back to us."
He added that it was ‘difficult" to say when people would be allowed to return to their homes permanently’.
A major operation involving the Environment Agency, Derbyshire Fire and Rescue Service, the Canal & River Trust, police, military and many others was launched after the dam wall became cracked and started to fall away
Police earlier today said around 200 one tonne bags of aggregate had been moved to support the reservoir wall, with a further 200 bags left at the scene which would continue to be added throughout the day.
There were 10 pumps from the fire service at the scene as of 3pm, with South Yorkshire Fire and Rescue assisting, and more pumps were due to be installed throughout the day to help lower water levels.
The damaged 180-year-old dam wall holds back around 1.3 million tonnes of water, and hundreds of people have been evacuated from Whaley Bridge over fears it could rupture and flood their homes.
No trains are able to run between Sheffield and Manchester Piccadilly, with the line expected to remain blocked until next week.