Watch: Sculpture of Environment Minister Nick Smith defecating in glass of water unveiled during Christchurch protest

A sculpture of Environment Minister Nick Smith defecating into a glass of clean water has been placed outside Ecan in central Christchurch this morning.

Sam Mahon says his sculpture is to highlight water pollution issues. Source: 1 NEWS

Around 20 protesters turned out to support artist Sam Mahon to highlight water pollution issues.

Mahon says when he grew up he could swim and drink freely from almost every river in Canterbury, now he can't.

He says it's one of the biggest issues the country faces and the Environment Minister needs to act on it.

"Ninety one per cent of our rivers are now polluted… I want my daughter to grow up having the same childhood I had."

The protesters are hoping their actions raise awareness and get people talking so they can tackle the issue together.

When asked what he thought of the statue Nick Smith said: "It's a free world ... people should be able to express their political opinions without having people's private parts out in the public arena."

He said, however, he's "not too concerned about it, you get pretty thick skinned in the trade I'm in."

National Party leader Bill English said during Thurday's first TVNZ leaders debate that National is cleaning up New Zealand's rivers.

"It is important we have clean rivers, it's part of our international brand and part of our Kiwi values and that's why over the last seven years we've worked with the land and water forum".

Yesterday Mr Smith filed a complaint with police alleging protestors rubbed rat poison over his face and clothes at a Nelson market.