Fighting faecal pollution in Southland rivers won't be a quick fix, but work has started.

A recent study found half of Southland rivers sampled had faecal contamination from livestock, and some had traces of human faeces.

Forty-two sites were tested.

Both types of contamination carry a very high risk to human health, because of diseases they transmit.

Report author Elaine Moriarty said Southland Regional Council is working with other groups to reduce river pollution, but the issue will take time to solve.

Dr Moriarty said it's important people stop to consider the health risks before swimming. It is best not to swim for 48 hours after rain, in all rivers.

She said people should check the Land Air Water Aotearoa website to see what the water quality is like.

"When they're at an actual swimming spot look around. Can they see something that's happening; is there something maybe that makes them feel a little bit uncomfortable or when they stand in the river if you can see your toes it's a good sign of a clean river."

She said a regional forum has started looking at how Southland's water is managed now, and how it will be managed in the future, including possible policy changes.

A community workshop will be held in Winton on Tuesday to discuss what action can be taken.

Main Image: The Waihopai River in Southland won an award this month for being New Zealand's most improved river but is still not in a swimmable state. Photo: Supplied / Cawthron Institute