Ōtaki Gorge Road slips

Ōtaki Forks and Tararua Forest Park is a taonga that has provided opportunities for recreation, education, fun, adventure, peace and much more over a very long time. It’s also on the Te Araroa Trail route.

Vehicle access to Ōtaki Forks remains closed.
Walkers are not to cross at Blue Bluff, for their own safety.
The Department of Conservation has established an alternative public walking access to the Tararua Forest Park.

Image: The slip on the Ōtaki Gorge Road at Blue Bluff. See larger image [JPG 476 KB].

Slips at Blue Bluff

Following slips on Ōtaki Gorge Road in 2020 and 2021 at the area known as Blue Bluff, it's been closed to vehicles and pedestrians for safety reasons. A Council decision in May 2024 means work to reinstate vehicle access is set to begin in the 2024/25 financial year.

The road access to Ōtaki Forks remains CLOSED at this time. There are two slips in the Blue Bluff area:

The September 2020 “slow slip”, which continued to shift for many months and saw the road slump towards the river.
The December 2021 “over slip” across the road, approximately 3000 cubic metres in volume and 100 metres in length, and which has continued to show signs of movement since.

The Blue Bluff section of the Ōtaki Gorge Road is 12 kilometres inland from the Peka Peka to Ōtaki Expressway.

It's an area that becomes active during wet weather. The road is on a steep embankment above the Ōtaki River, which is naturally degrading the riverbed and embankments. The Ōtaki Forks area receives intensive rainfall, further adding to the challenges of this road.

Restoring access

After a significant period of monitoring and investigation Council has opted to proceed with reopening the road.

A range of options were explored and presented for consideration. These included:

closing the road completely
building swing bridges across the river
building long-term walking access over the existing slips.

Staff recommended reinstating the road access and this option was adopted by Council.

Reinstating the road will be co-funded by Council and Waka Kotahi | NZ Transport Agency.

This is likely the quickest solution and will provide the most accessible route into the Ōtaki Forks and Tararua Forest Park.

More information on all the options and the proposed construction methodology for rebuilding the road is available in the Agenda for the Council meeting on Thursday 9 May 2024.

Council aims to complete detailed design of the repairs and apply for resource consents by October 2024, with work on the repairs to follow.

Timeline

Date	Activity
September 2020	Slow slip detected at Blue Bluff, Ōtaki Gorge Road closed for safety reasons.
Early 2021	Geotechnical monitoring and investigation into restoring access to Ōtaki Forks commences.
June 2021	Heavy rain reactivates slow slip, causing significant deformation of the road and the slip face to slump into the river.
October 2021	The road had stabilised enough to reopen part of it for a walking and cycling track along the wall side of the road. Site works had progressed to allow this to happen.
December 2021	Heavy rain on 6–8 December triggers over slip across the road. Cycling track destroyed.
June 2022	Walking track built to allow for monitoring and geotechnical work. Plans to open it to the public put on hold due to continuing instability on the over slip.
2023–May 2024	Ongoing investigations into options for restoring access.
May 2024	Council decides restore road access. Detailed design work scheduled to be complete by October 2024.
Early 2025	Subject to funding, construction begins
May 2025	Road due to re-open

About Blue Bluff

The Blue Bluff section of the Ōtaki Gorge Road, 12 kilometres inland from the Peka Peka to Ōtaki Expressway, is an area that becomes active during wet weather.

The road is on a steep embankment above the Ōtaki River, which is naturally degrading the riverbed and embankments. The Ōtaki Forks area receives intensive rainfall further adding to the challenges of this road.

Media releases