Protecting the Lewis Pass highway from river erosion, work timed to avoid nesting season


In preparation for a $2 million realignment of the South Island’s Lewis Pass highway (SH7), Transport Agency crews will be clearing a stand of trees this week. The road construction work will take place over the 2018/19 summer roadwork season.

The Department of Conservation (DOC) is working closely with the Agency to minimise the number of beech trees which need to be removed and to protect the wildlife habitat by ensuring the tree felling is well ahead of bird nesting season in September.

River erosion near the highway and the border of beech trees lining the river

This photo, taken with a drone, shows how the river is already eating into the side of the highway and the border of beech trees lining the river.

State Highway 7 is a key freight and tourist route between the West Coast and Canterbury, Nelson/ Tasman and Canterbury and Picton and Christchurch. It also runs through the Lewis Pass Scenic Reserve and national parks. In the event of SH1 via Kaikōura being cloed, the Lewis Pass is the only road link between Picton and the rest of the South Island. 

“The Department is working very closely with the Transport Agency on this project to ensure that the natural values of the important Lewis Pass Scenic Reserve are protected while supporting the Transport Agency in the realignment of State Highway 7, which is a vital traffic corridor in North Canterbury,” says Kingsley Timpson, Operations Manager, Department of Conservation, North Canterbury District Office.  

“The realignment is necessary as the Lewis River is cutting into the highway at Sylvia Flat, near the Boyle River, and eventually will undermine it, threatening the route. We need to realign 3-400 metres of road to ensure it is safely away from the river,” says Andrew Crofts, Senior Network Manager, Transport Agency.  Drivers may experience short five minute delays through this area this week daytime hours around the crews. 

The New Zealand native falcon/kārearea nests in the trees in September so no tree felling can occur once the birds are nesting. 

State Highway 7 realignment

The area of road being realigned is three kilometres past the Boyle River, on the west side of the Hanmer Springs turnoff and Island Hills. 

All of the felled trees will remain in the scenic reserve area as part of the DOC conditions. 

Further information on the New Zealand falcon/kārearea: link)