Constable Greg Nolet, of Wanaka, said at one point there was a kilometre-long queue of vehicles waiting to pass the slip yesterday morning.
The biggest rocks, which fell from a steep bluff just west of the Motatapu River, were the size of cars. Queenstown Lakes District Council acting chief engineer Richard Hilliard said a specialist technical assessment of the slope would be required before the rocks were moved.
A section of Mt Aspiring Rd would remain one-lane until then.