NSW's coal seam gas industry has a “complete lack of solutions” to deal with large quantities of salt, with one pilot project alone producing five tonnes of salt a day, a report commissioned by the state's Chief Scientist says.

Since the methane is typically trapped in rock fractures that also contain water, when miners such as Santos and AGL extract the gas they also bring water to the surface, much of it highly salty.

NSW's coal seam gas industry is struggling to deal with the large quantities of salt being produced.

In their report, University of NSW's Stuart Khan and Geena Kordek cited Santos' recently approved drilling project in the Pilliga Forest, in the state's north-west. It will probably produce an average of three tonnes of salt a day over three years, or as much as five tonnes daily during peak output.

The company is now building two 300-million-litre ponds adjacent to the Pilliga to hold water produced from its gas wells. Part of the operations were suspended in 2011 after 10,000 litres of untreated saline water leaked from a pipe.