The Department of Conservation announced yesterday it will re-open access to the remote Young Valley, near Makarora, on November 1, after more than a year.
Doc closed access to the valley and walking track because of safety concerns surrounding the 70-metre high rockfall dam, which created a lake nearly 2 kilometres long on the Young's north branch last September.
Geologist consultant Jeff Bryant has recommended to Doc, the Otago Regional Council, and the Queenstown Lakes District Council that access be permitted.
But certain restrictions, which can be imposed at any time should conditions warrant them, could close the valley again.
"It should be emphasised that lifting access restrictions doesn't imply there is no longer any danger or the dam is safe," Mr Bryant said.
About 30 Makarora residents were informed of the decision to re-open the Young Valley at a community meeting yesterday.
Makarora Residents Association deputy chairman Devon Miller said the closed valley had affected some of the tourist operators in the township, so the decision to re-open was a welcome one.
"It's a good positive announcement and the community is happy," he said.
The dam has been closely monitored by Doc, ORC, and QLDC since its discovery last year.
The most recent inspection was made by Mr Bryant last month.
"Our assessment is that the risk has diminished to more or less the level that would normally be expected in a mountainous area," he said.
The situation could change if extreme events, such as a huge rainstorm, a major earthquake or a wave in the lake, induced by a rockslide, occurred and compromised the stability of the dam structure.
However, these events were unlikely, Mr Bryant said.
Doc Area Manager, Paul Hellebrekers, said a valley closure and warning system based on weather conditions would be implemented in consultation with Mr Bryant and the Otago Regional Council.
"[Anyone] entering the valley must take responsibility for exercising caution and keeping themselves safe," he said.
A track through the lower Young Valley and south branch connects with the Gillespie Pass, a popular tramp in summer.
Mr Hellebrekers advised people entering the Young Valley to check weather forecasts and be prepared to turn back if they were entering via the Gillespie Pass.
Because the dam is still considered a hazard, QLDC emergency management officer, Brenden Winder, said Makarora's community response plan to cope with a dam breach would remain in place.
ORC environmental engineering and natural hazards director, Gavin Palmer, said the requirements for ongoing river monitoring and warning systems were under review.
