"I think it's terrible that a major corporate ... have not to date been open as to the state of the site," Parker told Morning Report.
The Government intervened to get the smelter to delay its shutdown until late 2024.
"We tried," Parker said.
"In the end, that was an agreement between the smelter and [power company] Meridian, the Government wasn't involved.
"They wanted us to get involved in respect of [electricity] transmission pricing.
"We said: 'Well, we might be up for that if you promise to clean up the site and tell us the state of the site.
"They wouldn't. So that didn't advance."
New Zealand Aluminium Smelters has been approached for a comment.
The Government had no power to intervene directly, so had given $300,000 to the regional council, which did have the power, under the Resource Management Act.
"They've got the power of entry onto the site. So I've asked them to go onto the site," the minister said.
"And I think they need to drill a few holes.
"I'm determined to get to the bottom of it."
Parker had put the Rio Tinto majority-owned smelter company on notice, he said.
The Environment Ministry said it had been engaging with the smelter since last September on how it would address its waste situation.
The tonnes of waste stockpiled by the beach at Tiwai Point - the residue of the lining inside the pots used to make aluminium, called spent cell liner waste, or SCL, or spent pot liner, SPL - are officially categorised as "hazardous waste", and some has been exported for disposal.
Workers handling it can be exposed to fluorides, crystalline silica, fluoride and beryllium, according to the International aluminium industry guidelines on SCL.
WorkSafe to assess smelter's compliance
Workplace safety regulator WorkSafe said it would be assessing the smelter's compliance with the Hazardous Substances storage requirements.
Its last workplace assessment was in February 2015, before the new and stricter Health and Safety at Work laws came in in 2016.
"This assessment included the storage of SPL on-site and no actionable issues were identified during this assessment," Worksafe said.
The smelter also had to comply when storing the waste with laws on hazardous substances, and with dangerous goods transport rules enforced by police.
The international SCL guidelines had no legal standing in New Zealand, WorkSafe said.
Invercargill City Council said, when updating its district plan, that planning approvals given to the smelter in the 1960s gave it "the right to operate virtually unconstrained by land-use conditions".
"The reality of this situation is reflected in the present zoning."
The city council sought a compromise between these rights, and the need to now address the land-use effects of the smelter's closure. It settled in the new district plan on encouraging the site's rehabilitation.
Toxic waste in Northland
And it was not alone, citing Sustainable Solvents in Northland.
"They brought all these solvents onto a site, they took the money to clean them up, they pocketed the money.
"And then they left behind this toxic waste site, which is a fire risk and we're having to spend a couple of million dollars ... to clean up the site. I think it's not good enough."
The Whangārei District Council has said it was trying to recover the costs from the company, for testing and disposing of 4000 drums of chemicals.
- RNZ
