Greenpeace has launched a report with the help of a herd of wooden dairy cows stuck in to Parliament's lawn.

The report, called "Sick Of Too Many Cows", is a collation of research that the group claims proves the health risk to New Zealanders from intensive dairy farming.

It's being backed by public health experts, including Health Physician Alistair Humphrey.

"In Canterbury we've watched the gradual contamination of our ground water and our surface water over many years," Mr Humphrey said.

"At the same time, as a doctor, we're seeing people get sick from this problem, and we're seeing the risk go up for our children."

A Maori health adviser was among those protesting today.

The Public Health Association's Keriata Stuart said there's a lot of concern in their membership that we're not doing enough to clean up our rivers.

"It is time to stop pitting farmers against public health workers, and communities against other people."

She believes people need to work together, and can "to get this solved."