The legislation is due to be passed shortly.
Melissa McGrath, WDC District Plan Manager, said it allowed developers to operate outside guiding local rules such as the District Plan.
"There are some serious alarm bells," she said.
WDC has sent in a submission on the Covid-19 Recovery (Fast-track Consenting) Bill, raising its concerns.
The legislation will take away the ability of the public and councils to have input into whether shovel-ready projects proceed, instead handing this power to a small panel of experts, chaired by an Environment Court judge.
Forlong said the fast-tracked projects would have benefits, but could also have many potential impacts that needed addressing. These included councils having to fund infrastructure to service them.
Forlong said the legislation had clearly been put together in a hurry.
Large projects, with potentially big environmental impacts, would be able to go ahead with only high-level RMA approval – and without detailed consent conditions.
Local authorities would be obliged to monitor them once approved. But this would be difficult without appropriate consent conditions being put in place.
There was a reliance on the "good grace" of those doing the projects under the fast-tracked legislation.
Forlong said there were potentially significant environmental impacts. These would more typically be from cumulative smaller impacts.
But the legislation allowed for the clearance of 1000 square metres of bush, as of right.
Forlong said Whangārei had vast areas of outstanding natural landscapes. These needed to be given adequate protection.
He said the legislation also needed to factor in more time for consultation with tangata whenua. Its current 30 working days timeframe was unlikely to result in meaningful engagement. It should also require that consultation to be at hapu level, rather than only at the larger-scale iwi authority level.
LGNZ has also submitted the legislation. It supported the intention but warned the "need for speed", with its reduced opportunities for public participation, should be balanced against the heightened risk of unintended consequences in some projects.
It said councils should be involved early on with the Environmental Protection Agency to meaningfully support the expert consenting panel's decision-making on the projects.