In its response to the commissioner's Heroic and the Dammed report on Canberra's Cotter water catchment, the government also said it would agree in principle to pass laws enabling the immediate removal of abandoned cars in the Cotter.

Icon Water collects a water abstraction charge from every bill, bringing in about $30 million a year for the government.

Environment commissioner professor Kate Auty said it was disappointing the government hadn't met its recommendation on the levy.

The government said the fund would go to consolidated revenue where it could then be allocated as part of the annual budget.

"The environment doesn't care about budget cycles," professor Auty said. "The fact that it's 'noted' doesn't really reflect what people advised me they'd like to see."

While the government insisted this levy was never hypothecated to bankroll infrastructure, it also said it was meant to reflect "the true value of water as a scarce resource".

The Cotter water catchment includes the Cotter Dam, the capital's second-largest drinking water source, and 300 kilometres of road through forest.

The commissioner was concerned abandoned cars would be set alight, causing bushfires like last year's Pierces Creek fire which burned 204 hectares near the Cotter.

The government will convene a working group to help consolidate resources to remove cars if "if they are causing a danger to the public".

Three CCTV cameras at the Cotter would act as a deterrent and help aid in investigations, the government said in its response.

But professor Auty said it was "urgent".

"The bushfire seasons are extending, they're not contracting," professor Auty said. "The recommendation is clear and I would have preferred that recommendation was adhered to."

The government said it would close off public access to the more ecologically sensitive or isolated areas of the Cotter.

It agreed in principle to have the Cotter's risk management plans reviewed and updated quarterly but said a formal review once a year was enough.

Professor Auty said she hadn't made her recommendations in a "bland, amorphous fashion".

"You'll find across a lot of the recommendations we spent a long time considering the wording and the timeline. Some of them have been agreed to in essence but our technicalities have not been considered."

The other recommendation included centralising the patchwork of agencies monitoring the water in the Cotter under a central group and coordinating resources.

The government said it would ultimately be up to rangers to maintain delivery of the plan.

"It is not appropriate for this task to fall to a committee," the government said.