Bulk water rates in one NSW region are set to increase by as much as 37.1 per cent, after a decision by IPART handed down on Thursday.
The decision has left Peel Valley irrigators in the state's New England region fuming.
Irrigator Ian Coxhead said it was particularly perverse to slam farmers recovering from years of zero-allocation and drought trying to get their balance sheets back in the black.
Some farmers could even leave the industry, he said.
"Those thoughts go through our mind all the time and this will sort of bring it all to the forefront again," he said.
"I know a few irrigators that have gone off farm and got jobs and they're farming now part-time. I think we'll see that increase as we get into higher charges for our water and our costs in general."
Water tends to be the highest cost for most irrigators, he said.
The Peel's high security water rates will hike by 37.1 per cent, general security by 34.4 per cent, and usage rights licences by 23.9 per cent. In the Namoi valley, prices will escalate by an even greater amount, by 57.2 per cent for high security, 17.7 per cent for general and 43.5 per cent for usage water rights holders.
Tamworth MP Kevin Anderson, who wrote a submission urging IPART not to escalate rates by double-digits, slammed the decision as "unfair".
"I think it's a kick in the guts. I'm talking about our farmers here. This is a kick in the guts. They haven't had water for so long, then when they do get decent rain and they get water to grow their crops and they finally get an allocation, they get slugged for it," he said.
"I certainly don't accept this price increase, that's why I'll be joining with the Peel Valley water users' association to look at what we need to to get some clarity around the pushback. We'll be meeting shortly, once the irrigators have time to get a good look at this report."
The Peel and Namoi Valleys already had some of the highest bulk water prices in the state, nearly ten times the rates paid by some southern water users.
Water NSW rates are based on the principle of cost-recovery - they reflect the cost to government to run the water utility.
Documents released with the price hike decision show it is operating costs that have driven the bill in the Peel Valley, increasing by 50.9 per cent since 2017 due to "increased expenditure on flood operations, metering and compliance, long term transformational strategy and asset management planning".
Capital costs have declined by 36.3 per cent "mainly due to increased expenditure on dam safety compliance", the documents say.
Mr Coxhead said Water NSW has trouble working within a budget, but tries to be as efficient as it can be.
NSW Irrigators' Council CEO Claire Miller said irrigators who went for years with zero water allocations still had to pay their annual water bills.
"It is cold comfort that IPART's pricing determination for the next four years is less than what WaterNSW and other Government agencies originally proposed," she said.
Water NSW asked for a 41.9 per cent price hike for high security licenses in in the Peel Valley.
A Peel Valley high security water licence will now set you back about $61.36 a megalitre. The price increase will kick in on October 1, 2021.
Water NSW has been contacted for comment on this story.