But  Kurri Kurri Landcare members wonder if they don’t do it, who will.

The group spent the best part of a decade working to rehabilitate old mine workings in their area – until state government bureaucrats told them to stop.

Using hydrated lime, the group’s members helped to neutralise acidic runoff from an abandoned coal stockpile that was poisoning a tributary of Swamp creek at Neath.

The Department of Lands ordered the group to stop dosing the creek about five years ago. The volunteers were told the work would be undertaken by Hunter Enviro-Mining, which was granted a licence to clear 3million tonnes of coal waste from the Cessnock area.

The work was never done and the company’s licence has since expired. Meanwhile the cocktail of sulphuric acid and iron and aluminium has returned and scorched a brunt orange path through the landscape.

Its effects can be seen 15kilometres away.

‘‘When we were previously treating the runoff it went from 2.5 (acidic) to 7 (neutral). It’s now gone back to what it was,’’ Kurri Kurri Landcare group president Col Maybury said. ‘‘The stream has also turned sideways and killed off a previously unaffected area.’’

The 2.5-kilometre long, five-metre-high coal stockpile is a remnant of a former coal washery that closed down 45 years ago. 

It is one of several similar environmental disasters that are the legacy of the former coalfields mineworkings. In most cases it has not been possible to prosecute the mines’ owners or force them to clean up the pollution.

Mr Maybury said the landcare group would be happy to resume treating the acidic water if given approval by the Department of Lands.

‘‘We just can’t understand why we were thrown out,’’ he said.

The department was unable to provide a response to questions about why the landcare group had been stopped from treating the water.

A Department of Primary Industries spokeswoman said: ‘‘Kurri Kurri Landcare had previously been working at the site using treatment methods that were causing other environmental impacts. For these reasons the group were asked to cease their activities.’’

‘‘Work by volunteer groups on Crown land is always appreciated and groups should ensure that appropriate approvals are in place before any work commences,’’ she added.