The concrete pipe, which measures 2mx4m and spans the width of the highway, became blocked with sediment as a result of heavy rain early yesterday morning.
However, a Waka Kotahi NZ Transport Agency spokesman said had the culvert not recently been updated, it might have been worse.
Golf Course Creek culvert was replaced in November last year as part of a flood protection resilience programme.
It was the second to be replaced. Pumphouse Creek culvert was updated in 2021.
The third culvert, Black Jacks, is due for renewal this year.
Yesterday heavy rain caused a slow accumulation of sediment to settle in the culvert and forced the water to rise, stopping short of flooding the state highway.
The spokesman said had the sediment built up in the older culverts, road flooding would have occurred.
The combination of rainfall occurring over a course of hours and a ‘‘significant’’ amount of sediment deposited in the rivers from the valleys resulted in sediment settling in the culvert, he said.
Central Otago Emergency Management adviser Derek Shaw was called to the scene because of the potential for residential evacuation and disruption to travel along the highway.
He said in some places the sediment was no more than 10cm from reaching the roof of the culvert.
The catchment above the stream was unstable and a considerable amount of matter had fallen into the stream bed.
He described it as an ongoing problem, with the only solution continued monitoring of the culvert.
