'Bloody important' wetland drained by digger during Alert Level 4

Tuesday, 19 May 2020

An excavator created a trench at Mahanga, near Mahia, to drain a wetland during Alert Level 4.

An investigation is underway after a protected wetland was drained through a trench created by an excavator during alert level four.

The wetland, which covers about six hectares, is at Mahanga, near Mahia, Hawke's Bay.

It is on privately owned land but has been protected by a Department of Conservation covenant since 2006.

Known simply as Mahanga wetland, it drains a short distance to the sea via the small Hine Rauiri stream.

The trench has allowed water to drain from the protected 6ha Mahanga wetland.

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The outlet of the Hine Rauiri Stream prior to the excavation work.

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The Mahanga wetland, behind the small settlement, has been restored since 2003.

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Police, the Department of Conservation and Hawke's Bay Regional Council were alerted by a member of the public on April 20 that a small excavator has been used to alter the mouth of the stream, and that the wetland was being drained.

The council's compliance manager Nick Zaman said a staff member visited the site the next day.

'Based on the photos supplied by staff the works undertaken did not constitute an Emergency Pollution Response under level four. We were more concerned about the breaching of Covid-19 level four restrictions,' Zaman said.

He said an investigation was underway and staff would be visiting the site this week.

'This is a longstanding complex issue that has been ongoing for a number of years for some of the community with a number of parties involved with differing views on what is required,' he said.

A meeting of all parties was planned later this week with a view to resolve these.

Wetland ecologist John Cheyne, who has studied the site, said 'it may be small, but it's bloody important, especially in a region that has lost 98 per cent of its freshwater wetlands'.

Cheyne said the wetland was visited regularly by endangered bittern, spotted crake, fernbird, and was home to long and short-finned eels, as well as being an inanga (whitebait) spawning area.

'A wetland like this can be reasonably dry for a short time, but manmade interventions like draining can cause huge ecological problems,' Cheyne said.

National Wetland Trust executive officer Karen Denyer was equally concerned.

“Given the extreme loss of wetlands nationwide, and how important they are, if a protected wetland was deliberately destroyed without consent we would expect prompt action from both the regional council and the covenantor. And if this did occur during Level 4 lock-down we would also expect a police investigation into non-essential travel or work,” she said.

Prior to 2003, before current owners began restoration work, the land had been drained and grazed.

Thousands of native trees had been planted in and around the wetland and weeds had been removed over the past 15 years.

A study Cheyne undertook for the regional council in 2014 said the wetland was a remnant of a much larger wetland. The wetland and stream had moderate to high ecological value and should be protected by raising its water levels in order to protect and improve the habitat.

A DOC spokeswoman said Hine Rauiri stream was not covered by the covenant, and the department was not concerned about the long-term impact to the wetland.

A Police spokesman said Police attended the site after receiving a call about the activity during Level 4.

'We attended and spoke to the people involved and it was established it was not a Police matter. Throughout all alert levels Police have taken a four-step approach to policing this unique situation, focused on engagement, encouragement and education with enforcement activity used for serious or persistent offenders,' he said.