It follows the declaration of the Kerosene Vale ash dump, which is adjacent to the former Wallerawang power station at Lithgow, under the Contaminated Lands Act.

NSW Environment Minister James Griffin told last week's Budget Estimates hearing that coal ash pollution remained a "significant problem" that many MPs and communities had expressed concerns about.

EPA chief executive Tony Chappel acknowledged the repositories posed a risk to the environment and human health.

"I think recycling and the waste hierarchy is always something we think about but our top priority is protecting the human health and the environment," Mr Chappel told the hearing.

The EPA has recently collected about 350 water samples and over sediment samples from Lake Macquarie as part of assessment of the current state of coal ash deposits.

The owners of the state ash dams have been asked to comment about the future regulation of the sites, which include heavy metals and other toxins. All of the sites will require extensive remediation and stabilisation following the closure of the adjoining power stations.

A spokesman for Origin Energy, which owns Eraring Power Station, confirmed the company had received correspondence about its ash dam. He said the company would respond in due course and would continue to engage with the EPA about the site's management.

The Hunter Community Environment Centre, which has campaigned for the clean up of the region's ash dams, welcomed the listing of Kerosene Vale ash dump under the contaminated lands act.

"The listing of Kerosene Vale ash dump will require NSW Treasury to re-evaluate its $2.2 billion contingent liability for the remediation of all formerly publicly-owned power station sites in NSW," a spokeswoman said.

"We are interested in the implications of this listing for ash dumps in Lake Macquarie and the Hunter, and will be watching closely the response of Delta and AGL to the EPA request to review reporting requirements."

The state government has allocated $37 million for a Carbon Recycling and Abatement Fund to trial new approaches to recycling, including for coal ash.

AGL signed an agreement earlier this year with waste remediation company NuRock to investigate the feasibility of converting millions of tonnes of coal ash at Bayswater Power Station into construction bricks.

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