Engineers battling to stop a dam bursting in South Yorkshire have said the situation is "critical but stable".
More than 700 people fled their homes after cracks appeared in a wall holding back Ulley reservoir, near Rotherham.
Teams had managed to stabilise the situation by pumping out as much water as was coming in via brooks and streams, Rotherham council said.
The number of pumps has been doubled to try to drive down the water level, and repair work on the wall has begun.
A South Yorkshire Police spokeswoman confirmed the water level at the reservoir was falling.
It is not yet known when the evacuated residents will be able to return home.
More than 70 firefighters, from as far afield as Hereford and Worcester, were working at the scene on Tuesday evening, setting up 17 high volume pumps (HVPs).
The HVPs will be pumping four million litres per hour out of the reservoir.
A fire services spokeswoman said crews were aiming to pump out enough water to reduce the dam height by 6ft (2m), to allow strengthening work on the dam wall to begin.
Adam Wilkinson, from the council, said: "The situation is critical and we will know more when we can pump more water out to relieve pressure on the dam.
"We're hopeful it will hold and we're doing everything in our power to make sure it does.
"There is more rain forecast and that, of course, presents us with further problems."
The M1 motorway has been closed, between junctions 32 and 36, because it would be flooded if the dam burst.
Water levels at the reservoir started to fall on Tuesday afternoon
South Yorkshire's Chief Constable Meredydd Hughes said: "It's not just the fact that the dam might break and the wall of water will rush to the motorway, it's also the fact that that water may take out a couple of pylons that are carrying 270,000 volts of power."
Rotherham police commander Ch Supt Matt Jukes told BBC Radio Sheffield the situation was "quite grave".
He said: "But it is a quite stable position. It's not getting worse but it's not getting better.
"All the important emergency procedures have kicked in."
Asked about the flooding scenario if the dam failed, the officer said: "The engineers are saying there is a possibility of water moving quite quickly."
He said the villages potentially in the path of any dam burst, including Treeton, Catcliffe and Whiston, were already experiencing river flooding.
A 68-year-old man and a teenage boy died in separate incidents caused by flooding in Sheffield on Monday.