DRY DRAINS: Tau and members of the Ngati Paoa emergency response team at the Hauraki Plains where eels are being rescued. Photo / Alison Smith
Some 2000 eels were evacuated from a blocked waterway of the Hauraki Plains after an emergency rescue was called last week.
The eels - or tuna in Māori - rely on moving, oxygenated cool fresh tidal water from the Piako River which in turn leads to the Firth of Thames.
Iwi kaitiaki Ngati Paoa say silt has blocked the passages designed to allow native eels to traverse between hot streams and the river, leaving the creatures trapped and in crisis.
Waikato Regional Council says the eels that are in the drainage system only have passage through floodgates which rely on gravity and water to be a certain height to open.
Due to no rain, the water in the drain is very low and, as a result, the floodgates have not been opening and have become silted up on the other side (from the Piako River). The eels also rely on rainwater which has been scarce
The regional council manages key infrastructure aimed at keeping the plains from being inundated by tides and river flooding. A number of other agencies also manage similar infrastructure within this area.
The iwi is calling for an emergency drought response plan and an urgent review of all flood management infrastructure on the Hauraki Plains.
"We gave [the Waikato Regional Council] an emergency drought response plan three months ago and it still hasn't come out," says Ngāti Pāoa kaitiaki Tau Hikaiti Paora.
"It's about how we move together, and we must, because our taonga is at risk."
I've seen them dry like this a number of years but it seems to be more frequent and longer".
"I've seen [the waterway] dry like this a number of years but it seems to be more frequent and longer, with more mortality, including birdlife. So I'm putting out there on my whenua what's happening."
Ngati Paoa brought in contractors to save the native creatures as pest fish began floating belly-up in the drains at Hopai East Rd near Ngatea.
The iwi has set up a business sampling water quality and testing soil.
"I've been involved with thousands of tuna on this site and today we pulled out another 350 eels," Tau said on Monday.
"We opened the pump up for half an hour and let some water in, and it's amazing, eels travelled out of nowhere."
Ngati Wai and Ngati Paoa worked together to help evacuate the eels with council staff.
Ngati Paoa applauded WRC for acting but were concerned that they had to call for the evacuation.
"If I hadn't been there, I worry that nothing would've happened."
In response, a council spokeswoman said there was an emergency response plan which had been implemented this summer and as part of that Ngāti Pāoa, along with other iwi and other agencies, were invited to help with monitoring, responding and updating the plan.
She said the council had been working with iwi, local councils, government departments and Fish & Game to develop a plan to mitigate and respond to dry weather on the plains, which threatens native fish species and birdlife.
The site has been monitored since early December as it was clear a dry situation was unfolding. The council made the decision to take preventative action at this site, with council staff, an ecologist and Ngati Paoa agreeing on actions to be taken.
WRC will use government funding for 10 flood-protection and catchment projects including replacing five pumps to allow for safe fish passage.
The council secured $16 million from the Government's COVID-19 recovery fund for flood protection infrastructure projects totalling $24.85 million. Some of this funding will be used to help minimise the ongoing impacts of drought on the Hauraki Plains.
Operations team manager Kenny Growden says the floodgates on the plains protect the land from the tides, as the area is up to 2m below the mean tide.
The gates close when the river is too high such as during flood or high tide to prevent water flowing from the river into a canal or drain.
"And when the river is low or tide is out, they won't open if there is not pressure - water - behind them to release them, such as if the water levels aren't high enough in the drains," he said.
On Friday the iwi called the council to return to the dry drains and silted fish passages it manages as more fish died.
Along with the tuna which were released, were a number of pest species including catfish, goldfish and koi carp which were removed.
Tau says about 2000 eels have been pulled out and released to the other side of the silted passage in recent days.
"Tuna are the hardiest to feeling the reduction of oxygen; when they die the whole lot is gone," said Tau.
Growden said WRC staff were monitoring the situation.
"Before Christmas, WRC recognised that there was unlikely to be much rain over the summer break so we've been closely monitoring the drains for trapped aquatic wildlife.
In December, we transferred tuna, inanga and mullet over a floodgate near Pipiroa."
But one long-time local says the silting is exacerbated by a "plug" of mud and Pacific oysters colonising the entrance of the river that has reached 1km proportions.
"It has totally changed the flow. That's why there's silt blocking them," says "Piako Pete" Thorburn, who has played in the area since age 11.
Now 63, he has a business selling flounder, eels and smoked fish.
He is one of four fishermen who rely on the river fulltime for their livelihood.
He said boats continually got stuck on newly forming mud banks, which are growing annually.
"The oysters are taking over and it's only a matter of time that the whole river will be shut. Up the Waitak, they've got a channel that's about 10ft wide and oysters metres high. They can't get out of their channel until two hours at least of the incoming tide.
"If the river is flushing properly I don't believe the gates will silt anywhere near as badly, but this time of year I believe the gates should all have been left open.
"When you see the amount of mud between the gates and the river, you have to ask yourself what fish can get over that?
"The farmers would probably welcome the bit of water on a spring tide that would come up their farms for a day or two."
In relation to the oysters, the council said it could possibly lead to more sedimentation on low flows, which does have a limited effect on maintenance activities regarding flood infrastructure. However, the gates will not open anyway, without internal water.
Ken Jones has lived on the Plains for nearly 90 years.
"I've seen a few changes. The main thing is getting rid of the water in winter and having it again in the summer to grow the grass."
He agrees opening up flood gates because of the drought would be "well worthwhile" for farmers and for the cracking roads in the area.
"Our water table seems to have disappeared and it's going to take a huge amount of rain to build it up again. The way the roads are cracked along some of those major drains is some major concern."
The regional council said it was not feasible to leave the flood gates open because then every high tide large areas of the Hauraki Plains would flood. This would also allow large amounts of sediment to deposit on land and drainage areas.
Retired farmer John Hayward lives near a floodgate on Hopai East Rd and last year caught and sent down the river 50-60 eels.
"They'll bury themselves in the mud and hibernate, they're a great species."
He says floodgates should be opened for a few hours a day and redesigned so they open vertically instead of outwards.
"It's a poor design. If it was on the edge of the river you don't get that amount of silt."
Growden said flood protection schemes were complex systems. "
They require site-specific considerations and infrastructure that are suitable for the conditions to achieve our levels of service while meeting our environmental obligations and objectives."
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One adult died at the scene and three people suffered minor to moderate injuries.