The woman was rescued from the Clyde and taken to hospital with serious injuries.
The alarm was raised around 7.55pm last night (Tuesday) when police received a report of a woman having fallen into the River Clyde near Stonebyres Power Station.
Emergency services, including Fire Service and HM Coastguard, attended.
The 25-year old-woman was taken by ambulance to Wishaw Hospital, but has since been transferred to the Queen Elizabeth University Hospital where medical staff describe her condition as serious. Police enquiries to establish the exact circumstances of the incident are continuing.
But the helicopter called to the scene developed mechanical problems and had to remain overnight in a field at the scene.
On Wednesday the A72 Clyde Valley Road from Lanark to Crossford was still closed just beyond Kirkfieldbank, with traffic diverted up the Lesmahagow road, while work continues on the helicopter.
Police and the fire brigade have been on the scene throughout.
It is expected that the chopper will be fixed by mid afternoon today.