Animal effluent main pollutant of Whanganui streams deemed unsafe for swimming

Swimming banned due to pollution at three popular Whanganui streams.

Faecal coliform bacteria from sheep and cattle are the main pollutants of three coastal Whanganui streams that now have permanent signs warning against swimming.

Horizons Regional Council's environment committee received a 15-page report about the streams on December 11.

The Mōwhanau, Kai Iwi and Ototoka streams at beaches north of Whanganui have been popular play places for children. Signs were erected this season, after monitoring last season showed they met bathing standards for E. coli 13, 8 and 4 per cent of the time, respectively.

The streams are "generally unsafe to swim in", especially after recent rain or when they are murky. If people do swim the signs recommend keeping their heads out, not swallowing water and washing hands before eating.
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A whitebaiter sets his net at the mouth of the Kai Iwi Stream. Whanganui Chronicle Photograph by Stuart Munro

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Making them swimmable is the number 1 priority for Whanganui Horizons councillor Nicola Patrick.

"These are the worst waterways in our region on this measure. They're also the most stunningly beautiful, safe and friendly for children," she said.

Her fellow Whanganui councillor, David Cotton, has lived at Mōwhanau for 30 years and twice drunk its water. He's never heard of anyone getting sick as a result of swimming in the streams and said they had run clearer for the past two years.

"We don't want to be alarmist about what's happening down there."

It's almost impossible to prove that an illness has come from swimming in polluted water, Patrick said.

"The community is asking us to help."

The main remedy for the pollution is fencing to keep stock out of the water, Horizons natural resources manager Jon Roygard said. An eight-wire fence suitable for keeping sheep out and protecting riparian planting costs $18 a metre.

He wondered whether the council might subsidise at a higher rate than usual, and said it would be best to work the fencing inland from the beaches.

Any coastal planting would also shade water for native fish and provide a place for whitebait to spawn.

But he said the council won't have any spare money to subsidise landowners for fencing until July next year.

"We are struggling to keep up with demand."

The fencing project would work better if the landowners led it, as they do in the Waimarino, Councillor Bruce Rollinson said.

"The community needs to lead it, and bring Horizons along as a participant."

There's no catchment care group in the Kai Iwi area. But Te Kāhui o Rauru might be willing to take the lead on the Ototoka and Kai Iwi streams, Patrick said.

MŌWHĀNAU STREAM
+ met swim standard for E. coli 13 per cent of last season
+ 29sq km catchment
+ 73 per cent land use sheep and beef farming
+ 1 dairy effluent discharge
+ 50 per cent of E. coli from cattle and sheep
+ 17km of stream fencing subsidised by Horizons

KAI IWI STREAM
+ met swim standard for E. coli 8 per cent of last season
+ 191sq km catchment
+ land use 51 per cent sheep and beef, 1 per cent intensive, rest forest
+ 50 per cent of E coli from cattle and sheep
+ part of Ngā Rauru Te Mana o the Wai project

OTOTOKA STREAM
+ met swim standard for E. coli 4 per cent of last season
+ 29sq km catchment
+ land use 80 per cent sheep and beef, 20 per cent dairy
+ 8 dairy effluent discharge consents, all farms compliant in November
+ 50 -100 per cent E. coli from cattle and sheep, mainly cattle
+ water at William Birch Pool no longer suitable for swimming
+ part of Ngā Rauru Te Mana o the Wai project