Garland said because the track was on an existing erosion site, identifying an alternative route not affected by further erosion would be ''challenging'' .
She said the new track would take several months to construct because the area could not be accessed with a digger and the track would have to be established by hand.
Wanaka i-Site spokeswoman Ling Wei said the 10km return track located 54km west of Wanaka was the third most popular summer walking track for visitors after Roys Peak and Mt Iron.
Even in winter five to 10 groups came into the Wanaka i-Site every day to inquire about the condition of the mostly gravel access road and the weather in Mt Aspiring National Park, she said.
An estimated 20,000 people visit the Rob Roy Glacier a year.
''Not being able to walk the track is definitely going to disappoint some people but you could still visit the glacier by helicopter,'' she said.
It is the second Department of Conservation track to be closed in the last few months.
The Diamond Lake and Rocky Mountain Tracks were closed on May 31 because of a rockfall and remain closed until further notice.
