A Far North District councillor says locals told her they contacted the Transport Agency concerned about a section of SH1 on Friday - the same day a 20 metre chunk of it was washed out after torrential rain.
It carved a five metre deep trench through the highway at Pukenui, 40 kilometres north of Kaitaia, slicing through the only public road to the tip of the North Island.
The councillor, Felicity Foy, said she had had messages on social media from people saying they called the Transport Agency to tell them a washout was likely because a culvert was blocked.
"I have only heard what I've been told ... I haven't had the time to follow that up. I'll have to go through the official channels to see what the correspondence was, if there was any, with the council.
"I think that's very serious if that actually occurred and they weren't able to respond fast enough that this has resulted in such a catastrophic event."
The road takes tourists to Cape Reinga, and not having it was a hit for the tourism in the region.
"This has immediate financial implications for our small communities," Ms Foy said.
Work on fixing the five metre deep trench continued today and the Transport Agency said it was on track to reopen the stretch of road by the middle of the week.
It is asking people not to use private forestry roads or the beach as alternate routes because driving there could be dangerous.