The NSW government has launched legal action against irrigators alleged to have stolen water after admitting it previously "incorrectly" claimed to have commenced a dozen prosecutions when there had been none.

WaterNSW on Thursday announced it had begun several prosecutions in the NSW Land and Environment Court, including cases involving a property highlighted in the ABC’s Four Corners episode Pumped.

The July 2017 program alleged there was widespread non-compliance with NSW water legislation, particularly in the Barwon-Darling river system.

WaterNSW alleges that cotton farmers Peter and Jane Harris, who featured in the program, took water when the flow conditions did not permit it and breached licence and approval conditions. The maximum penalty for each offence is $247,500.

Peter Harris said in a statement: “We look forward to an opportunity to vigorously defend these allegations. We have always believed we acted in accordance with the conditions of our water access licences.”

The announcement of prosecutions came as NSW ombudsman Michael Barnes tabled an updated report in parliament with new figures from WaterNSW which had previously provided inaccurate statistics.

The false data was included in a report which investigated water compliance and enforcement in NSW from 2007 to 2017, prompted by complaints alleging that water management rules were not being properly adhered to.

The report stated there had been 12 prosecutions between July 2016 and November 2017 when there had been none.

It also indicated there had been 105 infringement notices issued in the same period. None were issued.

The information published in the original report was “significantly incorrect”, Mr Barnes said in a statement on Thursday.

But the ombudsman concluded “the evidence does not support a conclusion that it was the intention of senior executives to wilfully provide misleading information”.

Greens MP Jeremy Buckingham labelled the new prosecutions a “smokescreen” for the damning ombudsman’s report.

“This government has been dragged kicking and screaming into actually having to enforce water law,” he said in a statement.

By Rebecca Gredley