Water quality's improving the Manawatu-Rangitikei region - and Federated Farmers says it's down their hard work with councils.

An independent report commissioned by Horizons Regional Council found a 5 to 8 percent improvement in 'swimmability' in the last 10 years.

Local Federated Farmers president Richard Morrison is quick to point out the improvements were not driven by regulation of farmers.

He says the results were because farmers worked towards solutions.

"Regulation's only in the case of market failure where things are going backwards fast and something drastic needs to happen."

The Council has however issued a health warning, telling people not to swim or fish in Makino Stream and Oroua River.

It says animal effluent has entered stormwater drains and contaminated the water.