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Kaituna River and estuary to be surveyed

Monday, 18 March 2013 8:00 a.m.

The lower Kaituna River and Ongatoro/Maketū Estuary could be a hive of activity early next month when it is surveyed to collect data on the area.

Bay of Plenty Regional Council staff and contractors will survey the lower Kaituna River and all of Ongatoro/Maketū Estuary to collect data that will help improve what's known about the area, including depth, salinity and currents.

From around 20 March to the end of April 2013, surveyors will be at work on boats, jetskis or on foot, with most activity happening on or around 4 April.

Senior Land Management Officer Pim de Monchy said a radio-controlled boat would be used to gauge the flow through the mouth of the estuary. Measuring instruments will be in the water for a month and a small plane will survey shallow waters.

"We're asking people to leave the instruments untouched to make sure good information is collected," he said.

The Council wants the information to help work out how more water from the Kaituna River could be re-diverted to its original course into the Ongatoro/Maketū Estuary to improve the estuary's health.

Mr de Monchy said the health of the estuary had been severely degraded since Te Tumu Cut was put in for flood protection in 1957.

"Since then 95 percent of estuarine saltmarsh has disappeared and 70 percent of the estuary's volume has filled in with sand.

"These changes have also affected the shellfish and other wildlife in the estuary, and the local community, particularly tangata whenua, want this to change," he said.

The data will be used to create a set of 3D models of the river and estuary, which in turn will help with assessing environmental effects of re-diverting the water.

Preliminary modelling shows that up to 21 percent of the river's flow could be re-diverted to the estuary while still leaving Te Tumu Cut open for flood flows, depending on where the water was taken from the river, what sort of structures were used, and where it was allowed to flow into the estuary. This would be a significant increase from the 3.5 percent that currently flows through Ford's Cut, and could create opportunities to re-create wetlands drained since 1957.

Photo:  NIWA hydrologist Julie Proud operates a radio controlled boat at the Houpoto site. Click on the image to download a high-resolution version.

NIWA boat remote small


NIWA boat remote small