A Hunter environment advocacy group has called for tighter water pollution limits to be imposed on the Hunter's coal-fired power stations.
A recent review of air emission data and licensing requirementsfor NSW coal-fired power stations resulted in the introduction of new air and water monitoring requirements.
However, the Hunter Community Environment Centre says tighter limits also need to be placed on the emission of water pollutants.
"The licence changes are a positive but tiny step and the public cannot yet be assured the EPA is protecting water from degradation by power stations coal ash pollution," Hunter Community Environment Centre spokeswoman Jo Lynch said.
The centre has been investigating heavy metal pollution from NSW coal ash waste dumps and will present evidence of water contamination at a NSW Government inquiry into coal-ash waste site remediation next month.
Metals present in coal ash are carried by water into the environment where they can be consumed or absorbed by people and organisms and bio-accumulate causing toxicological effects.
Heavy metals escaping from NSW power station ash dams include arsenic, boron, cadmium, chromium, copper, manganese, nickel, lead, selenium and zinc.
Revised environment protection licences for Mt. Piper power station at Lithgow and Vales Point and Eraring power stations at Lake Macquarie include requirements to monitor additional heavy metal pollutants (copper, iron and selenium) in water.
It follows a long-standing warning about eating fish caught from Lake Macquarie due to elevated selenium levels. A 2016 Department of Primary Industries report found that cadmium was also at potentially dangerous levels in mud-crabs.
However, no changes to monitoring or reporting were made for AGL's Liddell or Bayswater power stations in the Hunter Valley.
"We urgently need limits on all heavy metal pollutants emitted by NSW power station ash dams, in line with our national water quality frameworks and health guidelines," Ms Lynch said.
An EPA spokeswoman said decisive action would be taken against any licensee that does not adhere to the strict site specific requirements.
"The EPA will review surface and ground water monitoring requirements for all coal fired power stations in NSW," she said.
"The site-specific environmental and operational circumstances of each power station will be considered as part of this review."