Police have said the future of the dam wall at Toddbrook Reservoir in Whaley Bridge 'remains in the balance'.
Emergency services have been at the scene since Thursday morning, alongside partner agencies and volunteers after heavy rain caused damage to the dam wall.
A plan has now been put in place to try and secure the dam wall, but Deputy Chief Constable Rachel Swann said she wanted to remind people of the 'very real danger posed to them should the wall collapse.'
She added that a Chinook helicopter was being brought in to help move 400 tonnes of aggregate that will be used to divert water from entering the reservoir and into other surrounding watercourses.
“The response to this incident has come from far and wide. Emergency services from across Derbyshire, the region and across the country have provided support already and will continue to do so in the forthcoming hours and days," DCC Swann said.
“Ten specialist high-volume pumping fire appliances along with specially-trained fire and rescue flood advisors have been brought into the area from around the UK, utilising fire service national co-ordination arrangements.
“To move the substantial amount of aggregate into place – a Chinook helicopter will be operating in the area in the coming hours to allow precise placement and divert the flow of the water.
“With all that said, at this time the future of the dam wall remains in the balance and I would remind people of the very real danger posed to them should the wall collapse.
“I understand that being evacuated from your home is a very difficult decision and it is certainly not one that we make lightly."