Moutoa floodgates open to relieve pressure on bottom stem of Manawatū River

The Moutoa floodgates located between Foxton and Shannon are now open to relieve pressure on the bottom stem of the Manawatū River.

Horizons Regional Council regional group controller Ged Shirley says the floodgates divert water down a spillway that acts as a short cut to the sea.
“The bottom stem of the Manawatū River is windy and slows water down. As this happens the channel fills and risks significantly overtopping into adjacent properties.
“Diverting flood flows down the spillway reduces that risk but this doesn’t have any impact on water levels upstream. There’s a common misconception that opening the gates acts like a plug, draining upstream and dropping levels in the likes of Palmerston North and the Tararua District.
“We also can’t operate the gates until the river is within the operating range of 8.2 metres at Moutoa as there needs to be enough flow left to not deposit heaps of silt into the lower channel. So it’s a bit of a balancing act but the gates were opened at 10.40pm which was a bit later than we initially predicted.”
Mr Shirley says river levels in the Rangitīkei, Ōroua and Tararua District are all starting to peak and recede.
“The Rangitīkei River is reaching its peak at Tangimoana now and the water level is below the top of the stopbanks. We have staff onsite monitoring the stopbanks on both sides of the river tonight so that if an overtopping occurs, we can inform Manawatū District Council as they would coordinate any necessary evacuations.
“Overall the Rangitīkei River is remaining within its active flood channel, meaning there is some water in low-lying land adjacent to the river. This is the same alongside the Ōroua and Manawatū, and there is water in the Taonui Basin as the Kopane spillway is operating.
“There is still an orange rain warning in place for the Tararua District overnight and there may be some scattered showers in other parts of the region. While we don’t expect this rainfall to cause rivers to rise significantly, we will have staff in the ECC and on the ground overnight monitoring the situation.”
Mr Shirley says that Horizons and city/district council emergency management staff have been working long hours last night, today and will continue to do so over the coming days.
“We understand that our communities can feel anxious when events like this happen and we’re working really hard to provide as much reassurance as we can. The situation is also constantly changing so we’re adjusting our response as required.
“Finally we’d like to remind people to stay away from the water once daylight comes, rivers will still be high and fast flowing. We don’t want people to fall into the water, injured by debris lying around or get swept away unexpectedly.
“At this stage we’ll provide our next update in the morning unless the situation changes.”
Up-to-date information on river heights and rainfall is available via Horizons 24-hour toll-free Waterline 0508 4 FLOOD or via our website
Updates will also be posted to the Manawatū-Whanganui Civil Defence page:
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For sandbag and evacuation information please contact your local city or district council and stay tuned to your local radio stations for another option for civil defence updates.