An enormous and "offensive" sculpture of Environment Minister Nick Smith is sitting directly in front of the offices of Environment Canterbury in Christchurch.

Artist Sam Mahon created the artwork, which depicts Dr Smith with his pants down and squatting over a glass, to highlight water pollution issues.

"It was the simplest way to get my message out," Mahon said.

The double-life-size statue is designed to describe the "catastrophe of water and the government's abdication from its duty of care", according to Mahon.

He was served with an injunction preventing him from delivering the artwork to ECan last week, but instead placed the piece on the public sidewalk with a support group in tow on Monday.

In a statement, Mahon said he found "the poisoning of our children with cyanobacteria" to be offensive.

"As far as displaying Nick's genitals to the world, perhaps the (Ecan) CEO Bill Bayfield has never entered a gallery or visited the Vatican City and cast his gaze on the multitudinous penises in bronze and marble that swarm around the square, much to the delight of children, the pope and one or two extraordinary cardinals," he said.

Mahon plans to move the sculpture to Nelson next week.

Meanwhile, Dr Smith said he's not bothered by the statue.

"It is a bit crass, and there are far smarter ways of people expressing themselves without being offensive," he said.

"Politics gives one a thick skin so I am not bothered by it."

"I am far more interested in doing the hard policy yards that will actually improve management of freshwater on which we are making good progress."