Emergency crews are racing to save a damaged reservoir, as “terrified” residents fear their Derbyshire town could be flooded.
Police say the wall holding back the 300-million-gallon Toddbrook Reservoir could still fail despite about 24 hours of efforts to shore it up.
Part of the dam wall collapsed on Thursday afternoon.
The 1,500 people evacuated from Whaley Bridge amid “mortal danger” warnings will not be allowed home tonight.
But the water level has dropped by half a metre thanks to ten fire service pumps moving 4.2 million litres of water every hour – with more pumps on the way.
An RAF helicopter is also halfway through dropping 400 tonnes of aggregate on the collapsed section.