Slips couldn't be stopped - experts

Work continues on repairing walking tracks on the Mauao mountain at the entrance to Tauranga Harbou. Photo / Alan Gibson

Geologists say nothing could have been done to stop slips on Mt Maunganui's popular Mauao mountain after last week's torrential downpour which lashed the region, causing widespread flash flooding.

The park ranger has warned that pedestrians who ignored the signs telling them to keep off several of the walking tracks, used by close to a million people last year, were hampering clean-up efforts.

Most of the walking tracks on the 232m volcanic cone, at the north end of the beach town, were closed last week after two major slips and a dozen smaller ones covered the base track in waist-high debris.

It also caused erosion in the 4WD track which contractors had been evening out.

The MetService says the heavy rain on Tuesday last week occurred over too small an area for a warning to be issued. About 72mm of rain was recorded at Tauranga Airport between 9am and 6pm. But on either side of Tauranga, in Katikati and Te Puke, only a few millimetres were recorded.

Several businesses were also flooded and the surge of stormwater led to manholes popping up across the city and sewage spilling into the streets.

Mauao park ranger Mark Ray said all the loose dirt had been cleared away, and all the tracks were safe to walk on again.

"If the water's all pooling in one area and then coming down, we could deal with that. But because there are no obvious areas where it's doing that sort of thing, there's no preventative work we can do for stopping it in the future."

Pohutukawa and flax will be planted to fill in the slip areas in the next few weeks.

The popular mountain can have up to 5000 people through its tracks in a day, and several complained when they could not use it last week.