Mr Dall said the regional council, which had tried to be as accommodating as possible in a bid to reach a mutually acceptable outcome, had extended the deadline for bond lodgement three times over several years.
"The last two extensions were given to allow the New Zealand Oyster Industry Association time to develop a dedicated industry clean-up fund as its proposed alternative to a bond for each consent," he said.
In April this year councillors had agreed to a "final" deadline of June 30 for an acceptable industry-arranged alternative to be implemented, but that deadline had now passed with no resolution in sight.
The council was now poised to issue abatement notices this week, giving oyster farmers another three months to lodge the required bonds (or an acceptable alternative) or face further enforcement action, including daily fines of up to $750.
Mr Dall said that while councillors had some sympathy for the oyster farmers' position, and were reluctant to take formal enforcement action, they had a wider duty to all Northlanders to ensure commercial operators using public space in coastal areas left it in an environmentally acceptable state.
"Northland has already had issues with a number of oyster farms which have required expensive clean-ups, including about 20 in the Waikare Inlet alone," he said.
"Farms like these which fall into disrepair and/or are abandoned can have a number of adverse environmental effects, and also pose a navigation hazard."
He did not see it as unreasonable for the region's ratepayers to expect that those who were gaining commercial benefit from what was effectively exclusive use of public space should pay to clean it up if things went wrong. Given that Northland oyster farms included only several hectares of actual structures that would require a bond, which could be as little as $90 per hectare per annum, the costs were not prohibitive, he added.