Hundreds of people have been evacuated from the town of Whaley Bridge with police officers going door-to-door to notify residents.
Britain's new prime minister Boris Johnson has visited a dam that was so damaged by recent heavy rainfall that the adjacent town has had to be evacuated.
"There's a major, major structural problem with the dam. What needs to happen now is that the water all needs to come out, there needs to be a proper repair, a rebuild of that dam," Johnson said.
Hundreds of people were evacuated from Whaley Bridge with police officers going door-to-door to notify residents.
An army helicopter has been trying to strengthen the dam with stone and sandbags.
And pumps are lowering the water level at the 300-million-gallon Toddbrook Reservoir that is connected to it.
A heatwave last week resulted in the UK's highest-ever temperature being recorded.
That was followed by heavy rains in many parts of the country.
Then there was flash flooding that inundated some homes, roads and train lines.
Railway lines near the Whaley Bridge area have been closed.