The Cawthron Institute is defending its research showing the Manawatu River is heavily polluted.
But it says it never stated the pollution was the worst in the world.

The research by the Nelson-based institute has been slammed by some farmers for its lack of detail.

It showed the Manawatu River has the highest reading of depleted dissolved oxygen of 300 rivers and streams in North America, Europe, Australia and New Zealand.

Federated Farmers has called for the Institute to name the other 299 rivers on the list to back up its research.

The institute's ecologist, Dr Roger Young, says the research aimed to give the Manawatu-Whanganui regional council an indication of the Manawatu river's health.

Dr. Young and two other scientists have just presented their findings to the Manawatu-Whanganui regional council’s independent hearing panel, as the region’s One Plan hearings enter their final phase.