The ACT Environmental Defenders Office - part of a network of state and territory organisations aiding the community on environmental issues - has traditionally relied on federal funding to stay afloat.

But that federal funding stopped in mid-2014, despite the Productivity Commission urging for governments to continue support such organisations.

The ACT office managed to keep operating through alternative funding. But principal solicitor Camilla Taylor said those sources were temporary and unsustainable.

Now, the office is calling on the ACT government to save it.

Ms Taylor said they would be forced to close within months if no aid came in next week's ACT budget.

That would make it the first EDO to close in any state or territory.

"We've asked the ACT government to essentially provide funding to close the gap that was left by the federal government," Ms Taylor said.

"We're fundamental to the community and the environment and we form part of a robust legal system.

"So we're hoping that the ACT government will also recognise that and see our value."

Ms Taylor said the office only needed a small amount - a minimum of $130,000 a year - to continue operating.

The EDO plays an important role in providing policy and legal advice on environmental and planning law.

It also provides community education to inform Canberrans of their rights under the environmental laws of the ACT and Commonwealth.

Solicitors take on appeals on development approvals, and scrutinise the impact of changes to planning, environment and heritage legislation.

Other cases have involved pollution, noise complaints, dumping offences, and shielding Canberra nature parks from development.

The office has acted on tree protection cases, filed freedom of information requests, and helped defend listed endangered ecosystems from threats.

The ACT government has not provided operational funding in the past, given the federal government's usual support, but has provided grants for one-off projects.

Attorney-General Simon Corbell said the government recognised the important role of the office, but would not yet comment on whether funding would be made available in next week's budget.

Mr Corbell said it was simply not possible for the ACT to "fill every gap in funding to the community legal sector from cuts made by the Abbott-Turnbull governments".

"The ACT government will continue to advocate for the reversal of Commonwealth government to cuts to funding for the EDO, which has not been restored by the Commonwealth government," he said.

In 2014, the Productivity Commission's access to justice report examined the role of organisations like the EDOs.

It recommended that federal and state and territory governments should provide funding for "strategic advocacy and law reform activities that seek to identify and remedy systemic issues and so reduce demand for frontline services".

Ms Taylor said that if the ACT office closed, it would be unlikely to come back.

"I think it's important to say that if we do close, which would be in a matter of months, we will be the first EDO in Australia to close," she said.

"Other state governments around Australia recognise the value of the EDOs, and that's governments of all persuasions."