A vineyard operator in south western NSW has been accused of illegally pumping up to 13,000 megalitres of water beyond their water licence allocation.
It's the largest prosecution by the Natural Resources Access Regulator (NRAR) since it was set up four years ago to enforce water laws in NSW.
NRAR will allege the former owner of the vineyard near Wentworth bypassed water meters and unlawfully pumped the equivalent of around 5,200 Olympic swimming pools.
The regulator says the water was illegally taken from the Darling River between 2011 and 2015, which was shortly after the millennium drought when the Murray-Darling Basin and almost all the southern NSW cropping zones were still severely affected by dry conditions.
Director of investigations and enforcement Lisa Stockley, says the allegations are extremely serious, even though conditions in the area had since moved from severe drought to flooding in some areas.
"Periods of abundant rainfall have a way of taking attention away from the overall reality of finite water resources," Ms Stockley says.
"When people irrigate unlawfully, they're not just risking heavy penalties. Illegal water take can also cause significant harm to the environment and their own community," she says.
The regulator says illegal water take, and water meter breaches remain the most common offence in NSW that it prosecutes, with 78 people found to have done the wrong thing between July and September.
"Since irrigated agriculture often includes the largest water users within a particular region, the regulator has made this a priority area for compliance and monitoring activities," Ms Stockley says.
NRAR says prosecutions are its highest sanction and are a key part of maintaining public confidence in the enforcement of water laws in NSW.
The case is due to be mentioned in the NSW Land and Environment court on December 9.