Horizons closely monitoring levels in the Manawatū River

Horizons incident controller David Neal says current river levels show the Manawatū River could reach operating range for the gates in the early hours of Tuesday 8 September.

”We let farmers through the Moutoa spillway know earlier today there was a possibility of a Moutoa floodgates operation, and are calling them again,” says Mr Neal.

“We are hoping there won’t be a need to activate the floodgates. However, we have mobilised staff as the forecast peak river level means it is likely the gates will be operated.”

The floodgates divert water down a spillway which acts as a shortcut to the sea, protecting people and property along the lower stem of the river, says Mr Neal.
 
“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 likes of Palmerston North and the Tararua District.”
 
Meanwhile, the Makino floodgates are to be reopened after Makino Stream began to drop, says Mr Neal.

“These floodgates were shut to divert water away from Feilding township and into the Kiwitea Stream. The Makino Stream is now at a level where these gates can be reopened.

“Staff are continuing to monitor the conditions throughout the night and we will issue updates as and if needed.”

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.