FNDC promised in March to clean up the largest dump halfway along Russell Rd at the Ngaiotonga saddle, where a solid mass of rubbish stretched from the roadside about 200 metres into native bush. The rubbish crossed a stream feeding the Waikare Inlet.
The clean-up's progress had been slow so far, but FNDC advised they were still committed to it.
Mr Walker said it was a matter of persevering to make sure the council took action.
He said locals would be willing to help with the clean-up if bins were provided.
Extremely steep terrain meant the cost of professional removal of the dump, which included fridges, household rubbish sacks and several burnt-out cars, was exorbitant.
"We have received some quotations," said FNDC's general manager infrastructure and asset management Jacqui Robson. "However, it appears the cost of removing the rubbish could be significantly greater than anticipated. We are currently investigating options to address this."
FNDC would not reveal the prices it had received so far, citing commercial sensitivity.
Sifting through rubbish had so far produced evidence identifying eight offenders, who were fined $200 apiece. One of the fines had been paid so far, Ms Robson said.
She said FNDC was also initiating contact with the Department of Conservation, Northland Regional Council and other agencies to discuss options for dealing with illegal dumping both at Ngaiotonga and other sites around Northland.
The 200-metre-long pile is the same dumping patch which prompted Auckland woman Emma Lamont-Messer to contact the Advocate in February.
She came across it while holidaying, describing it as "a truly awful sight".