The Defence Department asked consultants to investigate contamination from firefighting chemicals in Wreck Bay, home to a small Aboriginal community and receiving some ACT government services, after run-off from nearby Defence base.

A creek running through the community's land was found to have poly- and per-fluoroalkyl chemicals - known as PFAS - contaminating water that is used for swimming and fishing.

Documents released under freedom of information laws show residents told a survey during the investigation they swam in creeks and the ocean in the Jervis Bay territory.

Consultants GHD received the responses in June and July 2017 as they waited nearly a year for the Wreck Bay Aboriginal Community Council’s permission to test contamination levels on their land.

The consultants also heard residents had stopped children from eating yabbies out of fear of contamination. Two residents described yabbies in Wreck Bay as being “deformed”.

ACT Health admitted in one email released under freedom of information it lacked data to respond to concerns from the Wreck Bay community about the rate of cancer in the village.

As GHD prepared to further survey PFAS contamination in the territory, residents told authorities of community fears about a cancer cluster.

ACT Chief Health Officer Paul Kelly said in an email sent in December it was unclear if this was related to Wreck Bay residents’ concerns about PFAS in Mary Creek, which ran through their land.

The health directorate only had “a couple” of cancer cases in Jervis Bay on record and suggested further enquiry be made through NSW’s cancer registry, as there was potential for overlap with Nowra in NSW.

“On further enquiry, as is often the case with Jervis Bay territory, it appears that they ‘fall between the cracks’, being classified as ‘other territories’ in the NSW Cancer Registry and therefore not analysed by NSW nor released to ACT. In limbo, I guess,” Dr Kelly said.

An ACT government spokeswoman referred questions about cancer statistics to the Department of Infrastructure.

"The ACT has no statutory authority to access health records including cancer statistics from Jervis Bay territory," the spokeswoman said.

In the documents released to Fairfax Media, Dr Kelly said the ACT government’s contract with the federal government in providing services to Jervis Bay territory required it to apply the same standards there as it did in Canberra.

“Not reporting on cancer statistics seems to me to be in breach of those principles,” Dr Kelly said.

He said he would like to "work through" any impediments to the ACT receiving and documenting cancer statistics in Jervis Bay territory in 2018.

After GHD received permission to survey the land, early raw results from tests of animals and plants in the area showed about half (66) of the samples in Wreck Bay contained PFAS at levels above health-based guidance values. The consultants told residents in May it was too early to draw conclusions from the testing.

ACT Health in June asked Wreck Bay Aboriginal Community Council if fish species tested in the area were regularly consumed by residents, and where they were caught.

The Defence Department expected to receive a draft assessment of risks to human health in August. It will later use this to form a plan to manage PFAS-contaminated areas in Wreck Bay.

A Defence spokesman said the department was conducting a detailed environmental investigation into the nature and extent of PFAS at the Jervis Bay Range Facility and the surrounding area.

"It is anticipated the detailed site investigation report and human health report will be published and presented at a community walk-in session by the end of this year, with event details advertised closer to the date," the spokesman said.

"The federal Department of Health advises there is currently no consistent evidence that exposure to PFAS causes adverse human health effects, however, as a precaution, they recommend that exposure to PFAS is minimised."

In a Defence meeting on the contamination in July 2017, it was noted that uptake of the water use surveys was slow and community barbecues were held to encourage participation. After about 20 residents responded, GHD learnt most swam in the area, and that more than 80 per cent consumed plants collected locally.

It was identified that some community members wouldn’t engage with the investigation at all, due to a mistrust following the conduct of previous inquiries. The Wreck Bay board, representing the community, was sceptical of the investigation.

In April 2017, the board decided not to grant access to the land for testing unless an independent expert was appointed to advise the community. The Wreck Bay Aboriginal Community Council granted permission for consultants to survey the area in February.

For years, toxic chemicals have leached from the Defence base into Mary Creek.

PFOS and PFOA ingredients were in firefighting foam used for defence training from the 1970s and were phased out in 2004. The national environmental health standing committee has reported there is no consistent evidence that exposure to the chemicals causes adversely affects human health, but recent reports uncovered a possible link with cancer among residents of RAAF Base Williamtown, near Newcastle.

A Defence spokesman said the department and an environmental consultant have worked closely with the community to ensure, among other things, the investigation scope incorporated indigenous culture and lifestyle.

"Defence understands the concerns of the Wreck Bay community and has put considerable resources into conducting the environmental investigation promptly, while respecting the indigenous culture and unique access requirements of the area," the spokesman said.