The "environment" has been getting about two-thirds of the water released from Burrendong Dam into the Macquarie River, reports a spokeswoman for NSW Water Minister Melinda Pavey.
In the three years leading up to the end of 2018, the Macquarie Marshes received more than a million megalitres (ML) of water from the dam, she said.
The drought curtailed environmental releases to the marshes in December 2018.
The release of information follows the slamming of the state government by Healthy Rivers Dubbo convenor Mel Gray for "allowing the dam to get so low" and putting the city's water supply at risk.
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"In any given year, Dubbo uses approximately eight gigalitres (GL) of water from Burrendong," she said.
"In the last water year... irrigation used 143.5 GL. That's a reduction on what they were going to use. Because of the drought they had to cut 30 per cent.
"I'm putting responsibility on the state government and not the industry itself. I believe the management of the dam through the NSW government, the water department and water ministry is responsible for allowing the dam to get so low."
The minister's spokeswoman responded with advice that in the past two years Burrendong Dam had received a total of 99 gigalitres of water.
"This is 40 per cent lower than the millennium drought inflows," she said.
On average the dam receives 1448 gigalitres of water a year.
Ms Pavey's spokeswoman said the "last big rains" were in 2016.
"Since then, our dams have staved off the worst effects of drought," she said.
"Water has been allocated according to the rules, with roughly two-thirds in the Macquarie going to the environment."
The spokeswoman said the government was working hard to extend water supplies by prioritising critical human needs.
"This means all water users are impacted, whether that be general security irrigators or towns on tight water restrictions," she said.
"Without emergency responses such as our investment of $30 million to expand the Dubbo bore field, towns below Dubbo, including Nyngan, Warren and Cobar, would be without water by March next year.
"These drought measures are not silver bullets, but they buy us time. We must stop pointing fingers and support our communities doing it tough."