Horizons operates Moutoa floodgates to relieve pressure on lower Manawatū River

Horizons Regional Council has opened the Moutoa floodgates to relieve pressure on the bottom stem of the Manawatū River.

Manawatū-Whanganui Emergency Management Group controller Ged Shirley says Horizons staff have been monitoring waterways across the region during the current weather event in anticipation of needing to operate flood protection assets.

“While a Makino floodgates operation has not been required to protect Feilding, the Moutoa floodgates were opened at 2.05am this morning.”

The Moutoa floodgates, located between Foxton and Shannon, divert water down a spillway which acts as a shortcut to the sea, says Mr Shirley.
 
“The bottom stem of the Manawatū River is windy and has a relatively shallow gradient, slowing water down. As this happens, the channel fills, risks significantly overtopping a 30-kilometre stretch and flooding adjacent properties.
 
“Diverting flood flows down the spillway reduces this downstream risk. However, this diversion has no impact on water levels upstream.
 
“There’s a common misconception opening the gates acts like a plug, draining upstream and dropping levels in the river where it flows through the likes of Palmerston North and the Tararua District.”
 
People who lease land along the Moutoa spillway were advised on Monday afternoon a gate operation may take place, says Mr Shirley.
 
“We appreciate the leaseholders taking action to move stock and drop fences before we operate the gates.”

People should continue to take care, listen to advice from emergency services and civil defence, and ensure they are prepared, says Mr Shirley.

“While the region has no heavy rain watches or warnings, rain is still falling in areas which have already experienced significant inundation.

“Many of our rain gauges have recorded large volumes in the past 48 hours. People wanting to explore this data themselves can visit envirodata.horizons.govt.nz.
 
“People should continue to stay away from low-lying areas and avoid entering flood waters. It should always be assumed flood water is contaminated. Anyone who has flooding on their property should contact their local city/district council.
 
“Flooded streams and rivers are also dangerous. Currents will be strong and debris such as logs will often be difficult to see.”
 
Updated information on river heights and rainfall is available via Horizons’ 24-hour toll-free Waterline 0508 4 FLOOD (0508 435 663), or online at envirodata.horizons.govt.nz.
 
Updates are posted to the Manawatū-Whanganui Civil Defence Facebook page, while weather warnings are available at www.metservice.com/warnings.
 
An explainer video about how the Moutoa floodgates work is available here.

Image: A snapshot of the Moutoa floodgates just before 2am Wednesday 22 April taken from Horizons' webcam network.