A resource consent hearing into the Central Plains irrigation scheme will end on Thursday, 20 months after it began.
Backers of the $135 million project say it will bolster the agricultural industry in Canterbury by irrigating previously arid, less-workable farmland.
But opponents say benefits will go to a select few, at the expense of many others.
The original proposal submitted by Central Plains Water for resource consent has already been rejected in part.
A revised application was heard in Christchurch this week along with a number of submissions against the changed scheme.
The last of those opponents will speak on Thursday before the commissioners reserve their decision.