Residents in Whaley Bridge have been warned that they could be away from their homes for "several days."
Prime Minister Boris Johnson has also flown to the area after the police warned the risk to life remained high.
In a press conference this evening Derbyshire Police have announced the news and said they would be allowing residents to return home for up to 15 minutes to collect personal belongings.
One person from each property will be allowed to attend one of the road blocks and speak to an officer where they will be signed in and out. Emergency contact details will be taken, along with the address that they will be attending. That person will be able to access the property and will be given 15 minutes to do so. That person should then exit via the same route they entered.
In a statement Derbyshire Police said: "The multi-agency response to the damaged dam wall at Toddbrook Reservoir has continued throughout the day.
"We understand that people have had to leave in a very short period of time and that in doing so they may have left vital items, and family pets, in their properties.
"Any residents that re-enter Whaley Bridge are advised that they will do so at their own risk and the risk to life remains high in the area.
"Should the dam fail, or there be a fear that a collapse is imminent, the emergency service vehicles will sound their horns three times and a loud hailer will also sound.
"Residents should leave the area immediately away from the dam wall and to higher ground.
"Residents are warned that the current situation regarding the period of time in which they will be away from their homes could be several days and that they should consider this when they are returning to their properties for essential items."