"The dairy factory's been gone for quite a few years and the river's quite clean through to the bottom," the councillor said.
"I think it's going to make a difference eventually ... it's all down to the cost."
South Wairarapa District Council planning and environment group manager Glenn Bunny said the council tests the river water periodically to comply with its waste water resource consents.
Greater Wellington Regional Council is responsible for the maintenance of the river.
Green Party co-leader Russel Norman said one of the party's main campaigns this year is to clean up the country's rivers.
He has seen many unsafe rivers all over Wairarapa as a result of faecal contamination, especially the Ruamahanga and Mangatainoka rivers.
"It's about making sure that our rivers are clean enough to swim in again ... it's got a number of elements to it," Dr Norman said.
The main steps to the campaign are setting standards for clean water, introducing a fair charge for irrigation water and supporting water clean-up initiatives. This would include financial support to councils to help with any initiatives introduced.
"The Ruamahanga's not in great shape, I was pretty amazed," he said. "When we went down to the river there was plenty of evidence."
Dr Norman said healthy rivers are essential for a healthy economy, as our clean, green brand underpins tourism and agricultural exports.
"The most basic thing we can do to protect rivers is fence them off. It does actually improve water quality," said Dr Norman.
"A lot of the Wairarapa rivers are pretty polluted."
