The Defence Department has accused the media of stirring up panic about a nationwide chemical contamination scandal, but admits it could have responded sooner.
Katherine has become the third Australian community to be offered free blood testing, after pollutants from old firefighting foams used at a nearby military base leeched into ground and surface water.
Residents were warned not to eat local fish which contain high levels of the poisonous substances used at Royal Australian Air Force Base Tindal.
On Wednesday night, Darwin residents were told two creeks located close to the city's air force base are unsafe for swimming after high levels of PFAS, or poly-fluoroalkyl, compounds were found in fish and crustaceans.
But Defence's Steven Grzeskowiak maintains there's no consistent evidence that exposure to the foam impacts human health.
"There is a degree of hyperbole in some of the reporting around this from some quarters; I personally think that's unhelpful," he said.
Katherine may follow Williamtown in NSW and Oakey in Queensland in launching a class action for compensation after blood tests were offered in those communities.
Mayor Fay Miller is calling for federal funding for tourism promotion and land buybacks to compensate for the town's reputational damage and plummeting house prices.
Mr Grzeskowiak confirmed aquatic life testing would be expanded from the Katherine River to the Daly River, with the results, along with a health risk study, due in April.
Mr Grzeskowiak says a new foam product, which Defence only uses in emergency situations, still contains "minuscule" trace elements of the inorganic PFAS compounds.
He says Defence transitioned to the new foam around 2004, following warnings from overseas about potential dangers, but that process took a couple of years.
He said it could take 200 years for the toxins to break down in the environment, but "nobody's really sure".
Canberra has installed a water treatment plant in Katherine, and is working with up to 30 global companies on possible techniques to rid PFAS from soil.
The country-wide clean up is likely to cost taxpayers hundreds of millions of dollars.
Many residents have slammed the Commonwealth's slow response, but Mr Grzeskowiak says Defence is at the "leading edge" of investigations within Australia.
"Nobody else was looking at this; there was no general concern in the environmental community," he said.
"With hindsight, when you look back, could we have moved more quickly? Yes we probably could."
