Horowhenua District Council has applied for resource consent for its Levin water supply scheme, which includes a big reservoir near the Ōhau River.

The reservoir would store water when the flow in the river is high, so it can be used when the flow is too low for water to be taken out.

The project would include drawing water from the river, building and operating a new reservoir and the necessary infrastructure, construction of new bores in the Ōhau River near the State Highway 1 bridge, and planting and restoration works in and around a wetland.

The current consent allows for a maximum of 15,000cu m/day of water to be taken out of the river. At present the water storage facility on Gladstone Road holds only enough for a day’s use. With the rapidly growing district this has been inadequate for some time.

In 2017, when the current consent was granted, district growth was estimated to be 2 percent by 2041, but it is now 2 percent each year.

The Ōhau River is also on an earthquake fault line, which makes an alternative storage option more urgent. Heavy rainfall leads to high turbidity in the river – the water treatment plant can’t cope, interrupting the drinking water supply.

The consents also include short-term drawing of water to help build the Horowhenua expressway.

The new reservoir will mean large scale earthworks will need to happen on Poads Road, as well as construction of a pipeline to the water treatment plant and reservoir.

The package of consents also includes work on stream enhancements, wetland maintenance, weed and plant removal, construction work in the lower terrace and floodplain area.

Water intake for the water treatment plant will remain at about its current rate as long as the water flow in the river is above its minimum of 15,409cu m/day. The reservoir will need 7500cu m/day, to increase to 15,409cu m/day in times when the water treatment plant can’t function.

To build the expressway the consents say 2400cu m/day can be extracted during construction.

There is also a non-consumptive consent for 750cu m at an existing plant intake. An additional take is consented for when the river flow is above minimum of 10 percent at the reservoir site.

When river flow is below minimum the intake will reduce to 13,000cu m/day and restrictions will be in place.

Council chief executive Monique Davidson says the project would give the district a critical buffer in times of water shortage.

“We could take water from the Ōhau River when flow rates are high and store it for when the river is running low,” she says.

The Poads Road reservoir would be 740,000cu m at Poads Road, near the Levin water treatment plant on Gladstone Road.

Resource consents for allocation of water take and construction in or near water bodies are granted by Horizons Regional Council, which has now publicly notified the application.

For the resource consent application, see Horizons