Questions are being raised about why a digger went looking for swamp kauri near the Marsden Point pipeline.
A Refining New Zealand report thinks the unidentified machinery is to blame for a scrape in 2014, which led to September's rupture.
But Fiona Furrell from the Northland Environment Protection Society isn't buying that, and thinks someone deserves to have the finger pointed at them.
"The diggers don't come in and dig randomly on people's properly. The land owner would know who the digger-driver was… MPI should be able to trace where the logs went to."
The onus falls on Northland Council to take action against those behind the rupture.
Ms Furrell wants the Ministry for Primary Industries (MPI) to keep a tighter leash on workers.
"We found diggers digging just about in any possible place they can in Northland, often just exploring to see if there's swamp kauri there. It's been out of control here in Northland for about a decade."
It's still unclear who was driving the digger.
The Northland Environment Protection Society says it'll have to wind up because it can't afford the $20,000 in costs awarded against it by the courts, after its case against MPI's alleged failure to regulate swamp kauri diggers was dismissed.
"It's the end of the road for us as a very small group with few resources but I feel we've achieved some good, and we are hugely grateful to our lawyers," Ms Furrell told RNZ.