A Defence Force investigation into toxic firefighting foam asked a council three times for water systems information as early as 18 months before toxic contamination at its nearby base was revealed.
It comes as anomalies and gaps in information continue to stack up.
Manawatū and Whanganui-based Horizons Regional Council told RNZ that Defence Force investigators had first asked for the information in April 2016.
At the time, a Defence Force consultant asked for "groundwater bore information and water permits within a 10km radius of both the Ōhakea and Linton NZDF bases for the purpose of investigating some groundwater issues and water supply upgrade options", the council told RNZ.
Investigators asked twice more - in September 2016 and again in July 2017 - about surface and groundwater permits within 15km of Ōhakea airbase, and information "relating to all boreholes and associated construction data, bore logs and groundwater and surface water takes within a 10km radius".
On those two occasions, it offered no reason why.
Then, in December, the Defence Force revealed water supplies at Ōhakea had been contaminated with the long-lasting foam chemicals.
The council's regulation group manager Nic Peet said the council was investigating the discharge and could end up prosecuting Defence, so he was limited in what he could say.
"Horizons' expectation is that information relating to contaminants being released into the environment, particularly where there are both environmental and potential health concerns, would occur quickly, openly and formally once the issue has been discovered," Dr Peet said.
"There is a particular onus on public bodies to act responsibly in this regard."
It comes after Auckland Councillor Penny Hulse last week expressed annoyance at how the Defence Force kept them in dark by not revealing Devonport naval base was contaminated and Whenuapai airbase was being investigated.
That was despite Defence - in a confidential briefing to the government last August - promising to keep local councils updated on the foam.
In the latest Air Force magazine, Air Commodore Andy Woods said "NZDF has very much led the way in investigating this [foam] issue in New Zealand. What we have learned will benefit all agencies."
Officials from the Ministry for the Environment also told Auckland Council a fortnight ago it had "new information" about Whenuapai and how local people might be using bores there for drinking water.
The ministry, which is the lead government agency on foam, has refused to answer RNZ's questions on the matter for the past two weeks, and would not explain why.
It would not say what the new information was, despite agreeing to "ensure all parties have timely access to accurate information", according to a confidential briefing in November.
Other foam types still in use raise further concerns
Fire and Emergency New Zealand has also admitted it does not keep track of how much of specific flourine-related brands of foam is used, even though very little is known about their environmental and health impacts.
Read Fire and Emergency's response to questioning:
PFOS and PFOA foams are banned, but other foams that have fluorine in them are still in use globally including four brands of foams used in New Zealand.
The service said 95 percent of the foam used in New Zealand were Class A, which are similar to detergent, used for vegetation and house fires and contain no flourine.
However, the remainder were Class B foams, which contain flourine and are used mostly to fight liquid fuel fires, in an estimated 33 incidents a year.
National urban commander Paul McGill said Fire and Emergency did not know exactly how much of these four brands they have been using.
"We don't know that accurately because the brand's not recorded at the time we use it," he said.
They were rated poorly in an environmental impact study by Fire and Emergency last year.
Read the study:
The agency also had not kept "detailed records" of how much of the fluorine foams it had used in training - and it is training that has caused by far the most contamination at multiple sites across Australia and the United States, and at New Zealand's Defence Force bases.
"Given the nature of our training use of Class B in recent years, [it] will have been relatively small amounts," the agency said.
Mr McGill promised they would bring in a new centralised system that would keep better track of foam use.
Firefighters stopped using the fluorine foams in training in mid-2017 but still use them at actual fires, at a rate of about 2000 litres of concentrate a year, creating 65,000 litres of foam.
Environmental impacts would be the number one consideration in buying future foam, Mr McGill said, followed by their performance against fires.
Manufacturers were close to developing the Holy Grail of foams, he added - a foam that was both fluorine-free and good enough to fight really hot fuel fires - and Fire and Emergency aimed to buy and use only a foam like that in the near future.