In September 2019, a leak in the Ravensworth ash line released 1,440 cubic metres of hazardous coal-ash sludge into Bayswater Creek in the Upper Hunter.

Following the incident, AGL Macquarie entered into an Enforceable Undertaking (EU) with the NSW Environment Protection Authority (EPA) which will see them spend record amounts in community payments, legal fees and rehabilitation costs.

An AGL spokeswoman said as part of the EU, AGL has developed a number of initiatives and projects valued at $1.108 million.

"The initiatives are designed to improve environmental performance at AGL Macquarie and within the energy industry," she said.

"This includes a contribution of $500,000 towards environmental projects for local community benefit.

"AGL takes our environmental obligations seriously and are committed to working with the NSW EPA to ensure that these initiatives are successfully implemented, and the subsequent environmental improvement outcomes are achieved."

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The EU is one of the biggest in NSW's history but Hunter Valley environment groups believe the response isn't tough enough and are calling for a parliamentary inquiry and an overhaul of coal-ash waste management.

Hunter Community Environment Centre (HCEC) is calling for a $20 levy on every tonne of coal ash dumped in dams.

HCEC spokesperson Jo Lynch said a coal-ash levy would enable waste that poses a high environmental risk on site to be transformed into high-quality recycled products ready for market.

"It's essential that the NSW Government support power companies to find safe uses for their waste to ensure incidents like these are avoided," she said.

Environmental Justice Australia lawyer Jocelyn McGarity said it was understandable that certain community groups wanted a tougher response.

"AGL has failed to meet its legal obligations and has endangered the environment, yet has again avoided criminal prosecution," she said.

"This is the second enforceable undertaking between the EPA and AGL this year.

"It comes after 52 licence non-compliances and numerous fines totalling over $100,000 in the past five years."