Herbert Guthrie-Smith once wrote: “Some spots on Earth inspire in their owners a very special affection.

“An occult sympathy betwixt the elementals of the soil … and those who touch its surface with their feet.”

He was speaking of an enchanted corner of Hawke’s Bay’s golden hill country, named Tutira, and celebrated for its romantic lake and the famed naturalist himself.

Running a large sheep station in the early decades of last century left him enamoured with this remote world, hidden high above Napier.

Its abundance of colourful birds and rare plants moved him to pen a classic of ecological writing.

But Tutira holds a different meaning for anyone who has spent more than an hour there.

Geologists know it as a remarkable time capsule, keeping in its muddy lake bed ancient traces of eruptions and earthquakes.

Anglers revere the lake as a hunting ground for good-sized rainbow trout, especially around its calm shores after a cold winter southerly.

For countless other Hawke’s Bay residents, it’s the place where they once swam, camped, hiked, kayaked, picnicked, fell in love.

“A number of people have told me they lost their virginity up here,” regional councillor Paul Bailey tells me with a smile.

“But it really is just an idyllic, beautiful spot – it’s pretty hard to beat.”

I was raised in Taranaki, but my grandmother often drove my brothers and me up to the little district she spent much of her life in.

We played amid the swans and the ducks and the weeping willows that fringe the shore.

We ate our lunch – home-made apple pie and pizza topped with canned spaghetti – atop a thick barbecue table at the water’s edge.

Three years ago, on a warm and blustery afternoon, my wife and I exchanged our wedding vows not far from that spot.

My grandmother was there with us.

Whatever it was about Tutira that had enchanted Guthrie-Smith, had struck us, too.

But Tutira’s story is also a tragedy.

What should be a postcard destination, no different from Wakatipu or Tekapo, is perhaps better now known as a trouble spot.

Decades-old water-quality problems have worsened over recent years, and swimmers are warned to keep away.

Headlines about fish and trout dying in water that became too anoxic or acidic have left locals disgusted and ashamed.

“I was talking to a couple of kids at the school,” says Bailey, “and they said that they were embarrassed to say they were from Tutira School, because other schools gave them a hard time about the lake”.

The lake that lies dreaming

My great grandfather once tried to capture Tutira’s tranquillity in a poem.

“Like a child at rest in its mother’s arms, Tutira Lake lies dreaming,” it opened.

“The hills embrace its tender charms, and understand their meaning.”

He and his wife stopped by in 1923, on their way into the bush where he worked.

That impression must have been as far as one could get from the terrible slaughter he’d witnessed at Passchendaele a few years earlier.

I often think of his words when I take the highway north from Napier, up to the lake.

The journey begins with an easy glide alongside the Pacific; it’s forever brilliant blue on that side of the island.

There’s a pebbled ribbon of beach that rolls all the way to one of those big brown headlands that jut out all along the East Coast.

Then comes the climb up into hill country.

You wind between swamps shaded by poplar and wattle, over ridges blanketed in pine, around a sharp 25km/h bend dubbed the Devil’s Elbow.

Lake Tutira emerges from the right, lying dreaming, just as my great grandfather imagined it.

If the day is still, the ridge that dominates its eastern side, and the bush and sheep upon it, reflect beautifully on to the water.

The mirror is even more dramatic at this time of year, when the willows are aflame in flourishes of autumnal amber.

This side of the lake is a reserve, set against a council-owned regional park that’s been largely planted out.

On the opposite side is 90ha of land belonging to the Guthrie-Smith Trust – the last of his old sheep station and his environmental legacy in the district.

There’s an education centre, where many of our wedding guests stayed, and an arboretum home to a host of rare and endangered species.

The trust was there even when my grandparents put their roots down in a local dairy farm, won in a ballot in the 1950s.

The landscape, too, was much as it is today.

My father grew up in a thriving little community that mixed around rugby and tennis games, fundraisers and days and nights at the golf club and pub up the road at Putorino.

He met my mother when she arrived to teach at Tutira School in the mid-1970s.

She tells me the lake’s woes were well known.

There were swims in rivers, but never in Tutira itself.

Laurel Teirney was there too, trying to understand what had made it so sick.

The first aquatic scientist to grapple with Tutira’s pollution recalls sharing her insights with local farming women and school children.

“They were all fascinated, but very upset to realise the run-off from their farms was causing the water-quality problems in the lake.”

‘A real cot case’

What has happened to Lake Tutira also has much to do with its natural characteristics, some of them unusual.

The lake’s inlet and outlet are both found at its northern end, and the lake bed itself plunges to 42m at its deepest point.

Because it can take most of a decade to turn over its water, the lake isn’t easily flushed, and thus makes itself a sediment trap for soils crumbling off the surrounding countryside.

That problem also makes it more vulnerable to the inflow of excess nutrients.

High loads of phosphorus and nitrogen are now recycled within the lake.

It’s increasingly because of a chemical release from sediments gathered at the lake bed, and brought on by a loss of oxygen in those deepest waters.

When Teirney arrived, top-dressing planes dousing the land with phosphorus had set Tutira on a steady course of decline.

“Fertiliser was dumped all over the catchment – even by DC3s – with no one knowing how much was really needed to promote growth,” she said.

“By 1973, when I began my study, the lake was munted – a real cot case.”

The green revolution delivered the biggest blow for Tutira, but it wasn’t the first.

Over the thousands of years after Tutira and its sister lake Waikapiro were created by massive landslides, the basin was draped in a thick mass of rimu, beech, totara, matai, climbers and ferns.

Maori settlers arrived in the 1500s and set about clearing the heavy podocarp cover.

In its place sprouted bracken and shrubs, which did much less to keep the ground stable.

The lake, situated along an ancient Maori travelling trail, always has been a bountiful and immensely meaningful asset to tangata whenua, who drew from its waters tuna (eels) and freshwater mussels.

Hapu still refer to Tutira as ko te waiu o tatou tipuna – the milk of our ancestors.

It’s a sad reminder of what they’ve lost.

“The health decline … has had enormous impact on our hapu due to unavailability of the once-prized tuna that was abundant,” local kaumatua Bevan Taylor says.

“Today there is very little sign of any existence of tuna.”

What forest and scrub that remained was again cleared in 1870s by the first European settlers, this time to make way for pastures and grazing land, which further added to erosion problems.

Still, in the early 1950s, the lake was clear, teeming with native fish and trout, and a popular recreation spot.

Taylor thinks fondly back to school visits in the 1940s and 1950s.

“Tutira lake during that period was pristine and beautiful,” he says.

“On lengths of logs, some of us would paddle out towards the centre, swimming in the lake most of the day.

“As the saying goes, we are the lake and the lake is us.”

Problems grew worse over the 1960s, prompting the formation of a technical committee.

Teirney arrived after an exceptionally hot spring to find a lake fouled by toxic blue-green algae blooms, and largely devoid of oxygen.

Anyone who swam in the khaki-coloured filth would have been left covered in rashes.

She herself suffered ear infections every month.

After two years of sampling, the project moved to aerating the lake.

Six massive aero-hydraulic guns were installed to move deep water to the surface, where oxygen could be absorbed during summer.

The approach was expensive, and the programme ceased.

“I could and should have written an account of the futile attempts to turn lake conditions around since the 1970s,” Teirney says.

Not long before my parents left the district for Morrinsville, the committee set out some hard measures to turn the picture around.

The most dramatic of them was slashing phosphorus loads by a factor of between five and nine times.

The bulk of phosphate entering the lake came in through the Papakiri Stream, via Sandy Creek at the northern end, and the committee requested it be diverted.

It also wanted erosion-prone areas fenced off, streams retired, new forest planted and farming practices improved.

Diverting the stream brought a noticeable change – its discharge into the lake was cut by three quarters in just a decade.

But much of that hard work of the early 1980s was undone when Cyclone Bola barrelled in.

An incredible 750mm of rain fell in just four days, pushing the lake’s surface level up several metres, and sending three quarters of a million cubic metres of sediment into the water.

Tutira itself took a $12 million hit.

The diversion was smothered, and later replaced, but big falls were still notorious for washing sediment and nutrients into Tutira.

“You can actually walk up to the top of the hill and watch it all coming in from that northern end,” local identity Blue McMillan says.

‘They completely freak out’

McMillan, a warm, easy-going sheep and beef farmer, manages the 463ha Tutira Country Park bordering the lake.

When the sun rises and burns the mist from the water, you’ll find him riding his red quad bike around the hills, dogs in tow, an old western hat pulled across the red hair that gave him his nickname.

He arrived in the early 1960s when his family won a farm ballot, grew up with my father, and was kind enough to host my wedding on a field in front of his old woolshed.

While running the park, he’s done much to replenish the landscape with greenery, allowing its steep slopes to revert back to kanuka.

He’s big on sustainable land use and dreams of Tutira again being as it was – a peaceful enclave of native bush.

“It’s always been a bit volatile,” he says of the lake.

“Usually the bad times have come with a climactic event, whether it’s big floods or dry summers.

“But it hasn’t been as bad as what it has been over the past decade.

“You can put that down to the fact that more nutrients are getting in from that northern end.”

Much of it could be blamed on farming in the catchment – nearly half is now dairy – but also the fact the inlet hadn’t been maintained as well as it should have.

“In the last five to 10 years, the management of that stream has changed, so it’s not getting cleaned out as much as it used to,” says Andy Hicks, a water-quality scientist at the Hawke’s Bay Regional Council.

The consequences have been severe.

In January 2016, scores of dead trout were found along the shores of the lake, not long after surface water temperatures had soared to 33C, the warmest ever recorded there.

Phycocyanin levels, indicating the presence of cyanobacteria, peaked around the same time.

The combination of warmth, extremely low levels of dissolved oxygen and ongoing algal blooms was a toxic cocktail for fish.

At the end of that year came another horrific die-off.

Just before Christmas, Wairoa residents Kev Gilbert and Hareena Prasad stopped to give their five children a chance to stretch their legs.

“We thought it was a good place to park up and eat, but the whole outer part of the lake was covered with dead eels,” Prasad said at the time.

“They were floating upside down and there was a sort of powdery colouring on the edge of the water.”

An “extreme” pH level of 9.4 was recorded at the lake’s boat ramp.

Health officials warned people to stay out of the water.

Hawke’s Bay Today declared the lake a mess, and that Guthrie-Smith would be “rolling in his grave” over what had become of it.

Regional council chairman Rex Graham doesn’t need reminding.

“The public see dead fish and they completely freak out,” he says.

“They don’t understand all of the work that’s been done behind the scenes, but you can’t blame them for that … if you see dead fish, hell, it concerns everyone.”

Anger also raged across social media, where videos of dead trout and milky green water were shared.

“Everyone seemed to have a solution for what was required to restore the health of the lake,” Paul Bailey says.

“Of course, a lot people are good at observing things going wrong, but not so good at coming up with the correct solutions.

Last year, regional ratepayers were told they’d be footing a 10 per cent rates hike to fund the cleanup of Lake Tutira and five other so-called hot spots.

Bailey, fronting the council as Tutira’s “ambassador”, believes the job can be done.

“It’s a challenge, but we are up for it,” he says.

The boost came on top of a $644,000 government grant awarded to the Maungaharuru-Tangita Trust to tackle the problems.

“The hapu is certainly being heard and valued – alongside our partners and the community,” says the trust’s general manager, Shayne Walker.

“An important factor here is working together.”

Graham agrees there’s been a shift in will that’s finally brought iwi, landowners and authorities together.

“Everyone is now sitting around the table talking about what we have to do to fix this lake – including most of the farmers,” he says.

“We are getting the funding in place now, and we do need a holistic strategy on the whole catchment and how we are going to do this.

But if even if current pollution can be reined back, it’s not clear how long the lake might take to recover.

I ask Andy Hicks if it will be decades before we might see Tutira healthy again.

“Well, even centuries … if you just improve things and hope that it happens just naturally, decades to centuries.”

“Every drop of water stays in that lake for two to seven years, but the sediment, the stuff at the bottom of the water, will stay there forever.

“And then the nutrients associated with that sediment … that will take a very long time to flush out.”

In the short term, there are some strategies at hand.

One is a curious device called an air curtain, which increases oxygen levels at all depths by creating a circulation current.

Working much like bubblers in an aquarium, it’s being trialled at Lake Waikapiro and, if effective there, may be up-scaled to Tutira.

But Hicks says there’s much to be learned before that happens – and the trial had a setback when dozens of fish died in January.

Staff spent half a day hopping from a boat to chase and capture the eels, before popping them into a barrel to transfer to Tutira.

It also isn’t clear whether using grass carp to chomp through hydrilla weeds on the lake bed had affected water quality.

Some scientists, Teirney among them, argue the carp may have even helped fuel algal blooms by simply recycling nutrients from the plants into the water column.

A lesson to heed

Months on from the fish kills, local anglers say the lake is the best they’ve seen it in years.

“I was up there a few weeks ago and landed two nice fish,” says Barry Robertson, who has been going to the lake for 50 years.

“The water is as clear as I’ve ever seen it – you can see about three metres into it.

“But at the moment, I’m having trouble catching fish, for the simple reason there aren’t that many in there.”

Fish and Game’s Hawke’s Bay regional manager Mark Venman says fewer trout were released this year, and some of the money saved went back into improving the habitat.

“A couple of anglers have reported catching adult trout from previous liberations and these trout have grown well over summer which is encouraging,” he says.

“It will be interesting to see whether mature trout return to their liberation sites this winter to provide sport for winter shoreline anglers; something that anglers haven’t experienced during recent years.”

There might not be a silver bullet to completely fix the lake, Venman says, but limiting the likelihood of more algal blooms will mean not having to deal with the headaches that come with them.

“From what I have seen so far with the scientific, cultural and historical knowledge, I am optimistic that efforts to restore the lake’s health will be successful.”

When he looks at the wider picture, Hicks views Tutira as a microcosm of New Zealand’s wider freshwater problems.

“You’ve got water-quality problems, and you’ve got different landscapes there, some of it intensively farmed, some of it hill country.

“Nationally, there has been a lot of attention on those more intensified landscapes, but that hill country, which you are generally not making much money off, that’s quite a big challenge, too.”

One of New Zealand’s most renowned freshwater scientists, Professor David Hamilton, has spent his share of time learning what’s happened to Tutira.

Those lessons need to be heeded everywhere, he says.

“A price is being paid for past legacies of sediment and nutrients that have entered the lake as a result of forest clearing and establishment of agriculture,” he says.

In catchments like Tutira, at least a third of the land should re-forested, beginning with those “critical source” areas where most of the sediment and nutrients stem from.

“We need to adopt restoration on a scale that is going to be effective – not messing around with little riparian areas that will not provide value for money in terms of work done and water-quality return.”

It’s a sentiment shared by Forest and Bird, a group Guthrie-Smith was proudly a life member of.

“If we’re really going to change the state of Tutira we need to manage surrounding land uses, as well as creating things like sediment traps and aeration systems,” its water spokesperson Annabeth Cohen says.

“It can’t just be an ambulance at the bottom of the cliff.”

Cohen points out Tutira isn’t alone: just a fraction of New Zealand’s 50,000 lakes are monitored, and many of those are in bad shape.

“We’ve seen so many lakes this summer unsafe for swimming, and those are just the ones we are watching.”

But for Teirney, the lake she tried to save all those decades ago stands as more than just a cautionary tale.

“It is the first terrible example of what happens when we inadvertently fill up our lakes with nutrients,” she says.

Otago’s Lake Hayes, a similar-sized lake being studied at the same time, is showing all the signs of the same decline.

“And in the past 10 to 15 years, I have witnessed many more of our lovely lakes succumbing to the same fate – even large deep lakes like Lake Taupo.”

Despite the optimism of others, she fears it’s too late for Tutira.

“I have compared the situation to that of our lakes needing medical attention.

“They give us all the signals that they aren’t well and should be taken to the doctor.

“Otherwise they end up in intensive care and finally the hospice. I see Lake Tutira is the first into the hospice.”

I hope she’s wrong.

Some day, I like to think my own descendants might be able to swim there, just as my great grandfather could have.

I ponder the last lines of his poem.

Who will be there in a thousand years? Will children picnic there? Will men be there with their hopes and fears, women with greying hair? Will man be divided, friend or foe? Will fear his joys dispel? Only the encircling hills may know, and they keep their secret well.

The state of our lakes

More than half of the lakes monitored in New Zealand are graded from average to poor.

The main measure used is called the trophic level index, or TLI, which combines four water-quality indicators to signify a lake’s life-supporting capacity.

Of 65 lake sites monitored between 2009 and 2013, 24 sites had median TLI scores of very good or good, 17 monitored sites had moderate scores, and 24 monitored sites had poor or very poor scores.

Over the same period, 12 sites had phosphorus levels too high to meet national bottom lines for ecosystem health, 11 had too much nitrogen, and 11 had unacceptably high levels of algae biomass.

This meant these lake sites could have ecological communities at high risk from nutrients causing algal blooms, or from not enough oxygen.

Long-term monitoring data showed levels of total nitrogen, total phosphorus, algal indicator chlorophyll-a and visual clarity were generally improving at lakes over the 2004 to 2013 period, but trends had been worsening for bottom-water dissolved oxygen and nitrate-nitrogen.

Among those lakes consistently rated bad are Lake Horowhenua, Lake Wairarapa, and Lake Ellesmere.

The Land, Air, Water, Aotearoa website grades Lake Tutira as poor.

In a five-year, $12m project, led by GNS Science and the Cawthron Institute, researchers will try to find out how 380 lakes around the country have changed over the past 1000 years