The Department of Conservation warned when it fixed the road around Christmas time that it was on borrowed time.
The landslip has remained active and it moved again last Friday, apparently pushing the Fox River to scour out the access road.
It leaves major doubt over the future of the road - used by thousands of tourists a month, who then walk up the valley to the view the ice.
Doc said the slip was the largest active landslip in New Zealand, and had been aggravated by recent heavy rain. There was no way to prevent the landslip causing damage in the valley.
The section of road damaged is about 300m long.
About 150m of road has been completely washed away and a further 150m substantially damaged.
Doc South Westland operations manager Wayne Costello said a decision about how to manage the access road would be made in the coming weeks.
"Because of the active nature of the slip, the access road is in a precarious position at present. Any repairs we do could be destroyed in the next heavy rain event,'' Mr Costello said.
"The road access to the glacier was reinstated just before Christmas at a cost of just under $430,000. It's likely that a similar investment would be required to reinstate access at this point - with no guarantee the work wouldn't be washed away in the next storm.
"The dynamic nature of the valleys and volatility of the landslide may well be unmanageable at this time. We may have to wait until conditions in the valley settle, which could be several years.''
Only 12 months ago, Doc spent $1million fixing the same access road, after it was damaged in the remnants of a tropical cyclone.
Doc said it would continue to look at other options for access in the Fox Glacier area.
Decisions about the access road are made in consultation with the NZ Transport Agency and roading and geotechnical engineers.
State Highway 6 remains open. The landslip prevents all foot and vehicle access to Fox Glacier, but air access is not affected.
