For 200 years the Hauraki Plains and Firth of Thames have been bent to the commercial interests of man. We have extracted timber, gold, peat, fish and shellfish, then tipped in millions of tonnes of sediment as our thanks. We have drained the marsh and farmed it, then intensively farmed it, returning the run-off of agriculture. Today, the region is a case study for the carrying capacity of land and sea. How resilient are our natural systems, and how much development is too much?
It was a slow conflict, at first, between natural forces of sedimentation and erosion, between the Hauraki Plains and the Firth of Thames. Into the rift valley that lies between the Coromandel Peninsula and the Hunua Ranges, the Waikato River poured the volcanic debris of the Taupō Volcanic Zone, filling the rift with pumice, gravel and sand some 2500 metres deep until it became a great embayment. About 20,000 years ago, the Waikato changed course, taking a sharp left-hand lurch halfway down present-day Lake Karapiro, forsaking the Hauraki Plains it had built. The plains remained wet and boggy, developing large stands of kahikatea and vast tracts of manuka and rushes. Peat built up in this marsh, 11 metres deep in places, and the open water of the Firth of Thames lapped at this indistinct edge, flooding and ebbing with tides and changes in sea level over thousands of years.
Two hundred years ago arrived a third dimension in the struggle between land and sea: commerce.
The first commodity was timber—the great stands of kahikatea and matai. Later, it was gold, then land itself became a commodity, conjured up from swamp with massive drainage schemes. This would allow for new agricultural commodities, and the latest boom, milk production, which was pioneered on the Hauraki Plains. In this featureless region between land and sea, there were few if any boundaries to development. It was open season for commerce and betterment. But for everything the plains offered up, something was taken away—the forests, the marshland, the clear productive waters of the rivers and coast of the firth.
This zone of land and sea would become the Petri dish for a young nation bent on development, a great demonstration of the power of primary industries to rapidly create wealth in the new colony, and the cost that would exact on natural systems and habitats.
Today, we can look at those old rivals—the Firth of Thames and the Hauraki Plains—not only as a resource to be harvested, but also as a barometer for the cost and benefit of development. It is here that we can ask the biggest questions confronting the nation: How much load can natural systems accommodate without breaking? How much development is too much? In this place without boundaries, where do we draw the line?
The first scene of the new act would be written by the crew of the Endeavour, who rowed up the Waihou River on November 20, 1769. Suitably impressed by its potential for development, Captain James Cook named it the Thames, an artery for the beating heart of an empire. Even the ship’s naturalist, Joseph Banks, had commercial development on his mind, labelling it “the properest place we have yet seen for establishing a Colony”.
The crew felled a matai, but most of the trees that lined the river were kahikatea. They measured one with a girth of almost six metres that was nearly 30 metres to the first branch.
“The Noble timber, of which there is such an abundance, would furnish plenty of materials either for building defences, houses or Vessels,” wrote Banks. “The River would furnish plenty of Fish, and the Soil make ample returns of any European Vegetables sown in it. Swamps which might doubtless Easily be drained, and sufficiently evinced the richness of their soils by the great size of the plants that grew upon them, and more particularly of the timber trees which were the streightest, cleanest, and I may say the largest I have ever seen.”
As the ink was drying on the Treaty of Waitangi in 1840, the Chief Protector of Aborigines, George Clarke, also saw potential in the Hauraki Plains. Heading up the Waihou, he commented, “The soil is good, sufficiently elevated to be secure from floods, part wooded, part clear, adapted for immediate culture… I have scarcely seen a piece of land to-day on which pretty farms might not be made and laid out to great advantage.”
His assessment of this new England was tempered, however, by the more marginal marshland to the west. “Every winter the swamp from the entrance of Piako to the interior, for about 30 miles, is an inland sea, in which nothing but water and the tops of a few kahikatea trees are to be seen, with canoes sailing in all directions over the expanse of water… I see no probability of redeeming a country so low, and receiving such an immense body of water from the interior… it must be many years before it can in any part be made available, and only then with the outlay of immense capital.”
Although the plains were wet, they were also flat, apparently fertile and handily located. That kept the eye of a government hungry for agricultural land fixed on the district. In 1876, Premier Julius Vogel agreed to sell the ‘Piako Swamp’—about 70,000 acres in extent—to a group of investors for half the advertised price of five shillings (50c) per acre, £10,000 for the lot. George Grey, MP for Auckland City West, bitterly denounced the sale as a sweet deal for Vogel’s rich pals, when the government could have developed the land into 400 valuable farms. The investors proved unable to drain and tame the land as promised, and it was taken over by the Waikato Land Association.
Meanwhile, on the eastern side of the plains, sawmilling of the lowland forest had begun. In 1869, the Hauraki Sawmilling Company commenced operations at Turua and became one of the country’s largest mills. By 1900, most Coromandel kauri had been logged, and by the outbreak of WWI, there was little timber left on the plains.
But the removal of the kahikatea forests was just an entrée for the main course: draining and reclaiming the land. The Hauraki Plains Act of 1908, followed by the Waihou and Ohinemuri Rivers Improvement Act 1910, set up a colossal project involving stopbanks, canals, drains and pumping stations along with roads, bridges and wharves. Between 1910 and 1914, 15,000 hectares was reclaimed and sold as 270 ballot farms—Grey’s vision was finally in action. Dairying quickly became the preferred type of farming in the district and many small dairy factories sprang up. Among them was Tatua at Tatuanui, now the sole remaining independent company in the lower plains and the country’s most successful.
In the past century, farms have grown steadily larger and the number of dairy companies reduced to give greater economies of scale. Today in the plains district—an area that includes the catchments of the Piako, Waitoa and Waihou Rivers—there are some 1500 dairy farms, on average 97 hectares each, running a total of some 437,000 cows. Though it is just the latest chapter of development for the district, it comes with an environmental cost too, and its share of detractors.
“New Zealand’s 6.5 million dairy cows produce effluent equivalent to 90 million humans,” proclaims Mike Joy, a senior lecturer in environmental sustainability and management at Massey University. He is speaking to an audience gathered for the launch of the Hauraki Gulf Forum’s 2014 update on the state of the region’s seas. Joy isn’t engendering optimism in the room.
“Seventy-four per cent of our freshwater fish are under threat, as well as mussels and crayfish, 62 per cent of rivers are unsafe to swim in because of pathogens, and we have the highest percentage of waterborne infectious diseases in the world.”
“Beware of ‘tobacco science’,” he goes on. “The dairy industry is fond of claiming that the release of nitrogen, phosphorous, pathogens and sediment to fresh water is stable when that’s not really true at all. There’s just a lack of sufficient data points to make the real deterioration statistically significant. Intensive dairying is just not sustainable.”
Far from being the country’s major export earner, says Joy, dairying is most likely a cost to the economy if you factor in environmental damage. He’s locked horns with dairymen many times in recent years. But is he right? Is it any worse than the two centuries of other primary industries, mining and logging that have changed this region? What is the real impact of intensive dairying, and can it be performed in a sustainable way?
My mother and her sisters grew up on a small dairy farm at Matatoki, backing on to the Waihou River. Till the day they died, they loved that place, speaking with the fondness of hindsight about trudging five miles each way to the main road for school, every day. Nearby were a number of relatives in a small, struggling and tight-knit community. When my grandfather died from a brain tumour in the late 1930s, my grandmother and her daughters—there was no son to continue farming—sold up and moved to Auckland.
The image of dairy farming today is a lot less benign. It’s widely seen as increasingly corporate and ruthlessly fixated on production and profits at the expense of the environment. Even as dairy farmers have been lionised by champions of economic growth, they have been vilified by councils, the media and the environmental lobby. They have been cast as mercenary polluters, as indiscriminate, even careless. Few are gifted spokespeople, or media savvy, and these allegations have largely gone unanswered, or worse, have simply been dismissed.
I wanted to find out whether this was fair in the Hauraki region, and how significant the impact of dairying might be on the adjacent Firth of Thames, often considered the most vulnerable part of the Hauraki Gulf. I’ve returned to my roots, visiting the lower plains to speak to dairy farmers still working the land in the spirit of my family a generation ago.
The eastern horizon is serrated by the Coromandel Range, and from a few spots you can glimpse the dead-flat summit of Table Mountain up the Kauaeranga Valley behind Thames. Periodic bridges cross canals and rivers—most the colour of liquid mud. At least parts of the plains are below the level of these tributaries, making water a significant factor in farming here. Roadsides are unkempt, largely due to two-metre-deep drains that fringe each road boundary. Long grass grows beside lesser drains around paddocks and there are regular piles of earth where diggers have been clearing them.
Despite the revenue earned from milking cows—it’s generally considered the most profitable type of farming—the area doesn’t look prosperous. The homes near Ngatea won’t make the pages of NZ House & Garden, and those aesthetic clusters of farm buildings that embellish other intensively farmed areas such as the American Midwest are completely absent.
Barry Flint milks 1000 cows, split into several herds in the Miranda-Kaiaua area. His family have been on at least some of the property since the 1930s. Flint is proud that he’s lifted the carrying capacity of the land from 2.5 cows per hectare to 3.2, though it’s cost him $1000 a hectare to do so.
“Drainage is the big thing,” he explained. “I’m on heavy marine clays and by gently humping and hollowing the paddocks, we improve drainage considerably. I’m now growing twice as much grass as 30 years ago. I’ve also switched from Friesian cows to lighter Jerseys. They cause less pugging damage and suffer less footrot, which means they can forage better.
“My father used to get 400 pounds of butterfat to the acre, which was pretty good, but I now get 1000 kilograms of milk solids per hectare.”
I try to do the maths: 400 lbs fat/acre = 790 kg total milk solids (which also includes protein). If he’s doubled grass growth, he’s only increased milk solids by a quarter, which is less than I would have expected.
Like elsewhere, potable water is a major issue on the plains. “It used to cost 22 cents per cubic metre, but now it’s increased to $1.88,” says Flint, who received an annual water bill from the council for more than $35,000 until he put down his own bore. That also cost $35,000, but promised to be only $3000 annually to run. He’s since discovered, however, that the bore water contains toxic levels of iron and boron, which costs as much to remove as the annual council water bill. “I’m stymied,” he says. With bitter irony, Flint also pays the council to maintain stopbanks and drains to keep unwanted water out.
As environmental scrutiny has increased on the plains, farmers have come under pressure to comply, no matter what their circumstances or the lay of their land—even Flint has had a run-in with Environment Waikato, the regional council. “From their surveillance helicopter, they saw I was grazing an area of about 20 acres beyond the seawall that I’d cleared the mangroves from,” he says. “Turned up here like the FBI in three vehicles flashing their IDs. Wouldn’t believe that I owned the land. It grew grass really well out there—I reckon it produced 8000 kilograms of milk solids.”
Flint withdrew his stock from the area but remains adamant that his family have owned it for some 80 years.
That night, I slept in my van by a friend’s house at Kaiaua, awaking to the sweetish smell of silage and distant cajoling whoops as cows were urged into a milking shed.
Down the road from Flint’s property in Waitakaruru is the Pukorokoro Miranda Shorebird Centre. I ambled down to the viewing area behind the shell banks and tidal flats favoured by the birds, to look across the mangroves and mud beyond the Flint farm. Nearby, a dozen campervans were doing the same thing—parked on a shelly spit while their owners lounged outside, gazing at birds against the backdrop of the Coromandels across the firth.
Some 125 species have been seen here, most of them fattening up on the broad and nutrient-rich intertidal mudflats of the inner firth. Over the summer, up to 10,000 birds may be present at a time, of some two dozen species.
In March 2007, a female bar-tailed godwit was fitted with a satellite tag here. By the time it returned six months later, it had flown 30,000 kilometres—including a non-stop 11,680-kilometre return flight from Alaska—in eight days.
The survival of these migratory birds depends upon protection of their habitat in all of the countries they visit. International recognition of what is called the eastern flyway—from New Zealand via Australia, South-east Asia and the Yellow Sea to Siberia and Alaska—has resulted in the establishment of a series of protected areas in a number of countries. Miranda naturalists have been associated with the Yalu Jiang National Nature Reserve in China. Following the 41,000-hectare reclamation of South Korea’s Saemangeum Estuary—during which up to 100,000 migratory birds seem to have perished—Yalu Jiang has become the most important shorebird staging site in the Yellow Sea.
In 1990, an 8500-hectare area of the southern Firth of Thames most favoured by shorebirds—the intertidal zone from the west bank of the Waihou River to Kaiaua—was declared one of New Zealand’s few Ramsar sites. Under the Ramsar international classification, the government is obligated to protect the site, but contaminated water from Hauraki dairying could threaten this area, and others along the long coast of the firth.
Along the western side of the firth towards the Hunua Ranges, the coastline changes quickly. Only 10 kilometres north of Miranda, the shore becomes bouldery, the gentle lapping of waves replaced by the gnashing of stones as small waves grind them back and forth. (Thousands of tonnes of round grey boulders have been taken from here for landscaping.) Rows of black buoys offshore signal that mussels are fattening on the plankton of the firth, and further towards Orere Point, sandy bays appear among the predominant rocks of the coastline, the area holding a series of fine regional parks.
Across the firth, on the eastern shore, a narrow road threads through pohutukawa struggling to keep a footing between the looming Coromandel hills and the predatory sea just below. Fishermen park their cars in tiny turnouts and cast from the rocks below. Shags are unusually common along this coast and there are several large roosting areas, including in the trees around the old Tararu cemetery. Trucks bearing mussels from Wilson Bay and Te Kouma farms now congest the tight corners, along with logging trucks.
This is a productive coast, for wildlife and for industry.
Peter West’s house is perched on a knob above the western margin of the Hauraki Plains at Kaihere, 25 kilometres inland from the coast. Fifty metres below, neat rectangular fields of his farm, and dozens of others, stretch out towards Thames and Paeroa.
West and his family have been here 29 years, originally as sharemilkers, later as owners, as he gradually bought bits and pieces of land. Now they have 180 hectares in 100 paddocks and milk 400 cows. Like many farmers, they graze their heifers (adolescent pre-milking cows) off the property and buy in a little palm kernel, but they grow maize and make sufficient silage to meet most of the herd’s needs.
As with much of the area, the farm was originally a peat bog, and as a consequence has settled between one and two metres over the past century. This has exposed ti-tree and large kahikatea stumps in places. Other paddocks are heavy clay and silt. Every paddock has had a soil test so West knows what fertiliser to use. He sprays cowshed effluent over 60 hectares of the farm to recycle nutrients, and like all dairy farmers, now has a large effluent storage pond (his holds two million litres) and another to store 200,000 litres—a week’s waste water—near the cowshed. Farmers are not permitted to spray onto their pastures when the ground is too wet (much of the winter) because it will run off quickly into waterways, so must have storage for up to three months’ effluent.
“The cost of upgrading effluent systems has forced out some small farmers,” West tells me. “The rules became tighter about the time the global financial crisis hit, when dairy prices were low and banks unsympathetic. Everyone around here has upgraded or is doing so. Some people used to have wintering pads covered with sawdust or post peelings, but it’s not always easy to contain the effluent from those and Environment Waikato now frowns on them.
“Coming to the meeting this afternoon?” he asks me. “Dairying and the environment, in the Ngatea Hall.”
By the time I get there, the room is packed. A smattering of suits is visible among 150 farmers. First speaker is a water quality specialist, Tom Stephens of DairyNZ, an organisation set up to assist the industry and funded out of a levy on milk solids.
He explains Environment Waikato’s network of 17 monitoring stations on the rivers in the area, which have now been collecting data for 20 years. It’s important information for farmers, as agriculture in the area is responsible for 46 per cent of the phosphorous and 70 per cent of the nitrogen in waterways.
“In the Piako River system, 42 per cent of indicators are improving and 46 per cent remain stable,” says Stephens. “Phosphorous is showing a steady decrease, whereas some nitrogen levels are down and some up. Only dissolved oxygen levels are deteriorating and that’s tricky to measure because of large daily fluctuations. In the Waihou River over the last 10 years, it’s similar. Most indicators are stable or improving.”
The message is, ‘We’re doing OK, but keep at it’, the sort of report that the ecologist Mike Joy criticised at the Hauraki Gulf Forum meeting.
Next comes Carla Muller, an economist from DairyNZ. She says that cow numbers on the plains have increased by 0.3 cows per hectare since 1990 and by 0.04 in the past decade—a one per cent increase. Most intensification occurred during the 1990s, a fact borne out by other statistics. During the 24 years from 1991, milk solids from the Hauraki area (just a part of the plains) have increased 43 per cent—made up of a genetic improvement of 14 per cent per cow and a 25.7 per cent increase in cow numbers on seven per cent more land. In the decade from 2001, however, stock numbers were static, productivity per cow increased slightly, but herd size continued to increase while the number of farms was still shrinking.
While the dairy industry is criticised for rampant intensification, much of that—at least on the plains—occurred two decades ago, and it doesn’t appear to be an ongoing process. Some farmers have experienced diminishing returns as they intensify production; for others the requirements for effluent handling and the like have become too costly. Still others, such as Barry and Kate Came, who farm 330 Kiwi-cross cows on 110 hectares further south on the plains, regret the pressure to expand and intensify.
“You’re made to feel you’re unsuccessful unless you’re expanding all the time,” Kate tells me. “But this has serious social consequences. It means there are ever fewer farm owners in an area like this to get involved in local communities. Most of those who work on farms are now transitory workers who’ll only be there for a year, two at the most. They have no roots in or commitment to the local community, and I’m very sad about that. It makes rural teaching difficult and the kids can’t build up stable friendships.”
The Cames say that farming used to appeal because you could be your own boss, but that’s becoming less true. There are tighter environmental and safety regulations constraining farmers, and greater demands from Fonterra too, upgrades costing tens of thousands each. The farmers I spoke to during the production of this story were only too aware of the opprobrium they were held in by many non-farmers and felt somewhat persecuted, even wronged. More than one mentioned to me that when local authorities discharge urban effluent illegally—through equipment malfunction or overflows etc—they are never prosecuted, whereas dairy farmers are.
All understand the soils they farm, do regular tests and apply only what fertilisers are necessary. (This is a commercial decision as much as environmental—a 100-hectare farm might spend more than $50,000 a year on fertiliser.) They use nitrogen fertiliser, such as urea, to increase production, a change from 30 years ago when most depended on the nitrogen-fixing properties of leguminous plants such as clover. But rather than use it in large doses, they apply it in small dressings periodically, even if it increases the spreading costs, and use less soluble forms of nitrogen to reduce leaching. The problems around milking-shed effluent disposal are well understood too, and they’re doing their best to comply. But such effluent is only a part of the problem.
“Cows spend 90 per cent of their time outside in paddocks, and so 90 per cent of their dung and urine is deposited there,” says Rob Dragten, farm compliance manager for Environment Waikato. “A urine patch contains nitrogen equivalent to 1000 kilograms per hectare per year, and that’s too much to be quickly absorbed by the roots of grass, so most enters groundwater and percolates into streams.
“Dairy is a high-intensity farming system and that drives the nitrogen cycle more quickly—nitrogen stimulates grass growth, cow eats grass, makes milk and excretes excess nitrogen back onto grass. And each spin drops out more nitrogen.”
Downstream from those farms, excess nitrogen can lead to acidification and eutrophication of riverine and marine ecosystems and the stimulation of algal blooms that suffocate surrounding organisms by sucking oxygen out of the water.
Yet solving the nitrogen problem is complex, and a lot broader than just effluent disposal. To help with effluent management are various online calculators, DairyNZ has a lot of information on effluent systems, and it also has a dairy ‘warrant of fitness’. Fonterra, too, has environmental staff, and a local manager does a thorough site audit of every farm each year.
“Uptake of all this is pretty good,” says Dragten. “We have 4200 dairy farmers in our area—Ruapehu to Franklin—and annually we’ll monitor 750 farms and bring three or five prosecutions. But there are some who don’t comply.”
Solving the broader issue of nutrient run-off possibly involves changes to land use and regulations in regional plans, and that’s a slow, painful process. Experience in Taupō provides a useful gauge on cost and potential benefit of aggressive mitigation. To protect the lake, strict intensity limits have been put on farmers and some land has been retired from grazing into forestry. Nitrogen can be traded between farmers, but no more than prescribed limits can be applied or discharged. It’s been a bruising and expensive business.
Many farmers have sold out and the value of farmland around the lake has crashed. The government has spent tens of millions buying farmland, just to reduce nitrogen-leaching by 20 per cent. Although farm productivity has been reduced considerably, it’s not certain that these measures will actually protect the health of the lake because decades can pass between the time nitrogen hits pasture and when it appears in waterways. Repeating this process in every catchment around the country would be economically ruinous to the nation. Would less-drastic measures have worked?
Every biological system has a level of tolerance—some are resilient, with powerful means to scrub or disperse pollutants, others are fragile. What is the carrying capacity of the Firth of Thames?
The major rivers in the south—the Waihou and Piako—carry about 3000 tonnes of inorganic nitrogen and 250 tonnes of phosphate from agriculture each year, according to Environment Waikato. This passes into the firth, and more nutrients could wash in from elsewhere in the Hauraki Gulf. A further 300 tonnes of phosphorous comes from the area’s towns and soils, and 1000 tonnes of nitrogen enters from other sources (including from lightning, which turns atmospheric nitrogen into forms available to plants). Another 3000 tonnes of nitrogen comes down rivers in particulate form (such as bacteria, plankton and fungi) which, when combined with the nitrogen production entering the firth from the gulf, brings the total input to just over 10,000 tonnes of nitrogen per year. However, according to a NIWA study, the firth denitrifies more than 10,000 tonnes of nitrogen compounds every year, returning them to the atmosphere as harmless nitrogen gas, more or less balancing current inputs. Despite the overall balance of this nitrogen budget, there can be local imbalances—especially around river mouths and fish farms.
NIWA has also measured lowered pH and oxygen levels associated with the release of increased amounts of carbon dioxide during late summer and autumn, when waters become stratified in the firth. These are signs that too much algal growth may be occurring, a sign of too much nitrogen in the water despite the apparently balanced budget. Oxygen concentrations in the Piako River also tend to be low, though Environment Waikato scientist Bill Vant suggests that organic matter released from the Kopuatai Peat Dome reduces oxygen down river.
Ironically, human industry at sea may help to offset industry on land. The outer firth hosts 2900 hectares of mussel farms, mainly between Wilson Bay and Kaiaua, accounting for almost a quarter of New Zealand’s mussel production. Mussels depend upon plankton in seawater to grow, and a large mussel will filter 350 litres of seawater daily. In doing so, mussels consume plankton, which is part nitrogen-based protein, and when harvested, around six kilograms of nitrogen is removed from the ecosystem for every tonne of mussels. At current rates of harvest, the mussel industry removes a modest 126 tonnes of nitrogen from the firth annually, and even with increases in aquaculture, it’s unlikely to exceed 500 tonnes.
In December last year, applications for expansions of firth mussel farms totalling 5100 hectares came off suspension, meaning there could soon be up to three times more hungry mussels between Kaiaua and Wilson Bay. Another, potentially even larger, project promoted by the Hauraki Gulf Forum aims to re-populate wild mussel beds.
Early last century, some 500 square kilometres of the firth seafloor was carpeted with large green-lipped mussels, but commercial dredging exterminated these by 1960. A study of remnant mussel beds found they were rich environments, harbouring a variety of organisms that prefer hard substrates and structures to cling to on the sea bed, such as sponges, starfish and anemones. They also provide cover for young fish and contain some five times the biomass present in sand or mud. The power of these vast, wild mussel beds to filter plankton is still relevant today as it’s estimated they could filter all the water of the firth in a day, versus two years for remnant mussels.
Efforts to re-establish mussel beds have begun using reject mussels from commercial farms. To date, 60 tonnes of mussels have been spread over a four-hectare area at the eastern end of Waiheke Island, where sedimentation is less of a problem. Subsequent monitoring of these re-seeded beds has indicated a high survival rate (better than 95 per cent) but little recruitment, indicating that environmental factors may be limiting the mussels’ ability to spawn, or larvae to survive. Solving this mystery will be crucial to the viability of the long-term project to restore the mussel beds of the firth, especially in locations with more turbidity than in the trial areas—which is almost everywhere.
Excess sediment can smother bottom-dwelling organisms, such as mussels, interfere with the gills of small fish and clog habitats. It is estimated that 350,000 tonnes of sediment enters the Hauraki Gulf each year. The Piako carries 30,000 tonnes per year, and the Waihou—with a similar catchment size—160,000 tonnes. Slips and erosion on the steep western face of the Kaimais account for the higher sediment load in the Waihou, says Environment Waikato scientist Peter Singleton, and all that material ends up in the firth.
“Those big Hauraki Plains rivers are most unusual. Their fall is very gradual towards the mouth,” says Bill Vant. “As a result, salt water goes 15 to 20 kilometres up these rivers, stirring up bottom sediments as it intermingles with fresh water coming down. So when you cross the bridge at Kopu, the mud you’re seeing in the river isn’t washing off dirty dairy farms at all.”
Land, Air, Water Aotearoa—an association of councils, Massey University, the Cawthron Institute and the Ministry for the Environment—rates the Waihou at Te Aroha in the worst 25 per cent of similar sites for turbidity, nitrogen and phosphorous and in the worst 50 per cent for bacteria. Only on acidity does it score in the best 25 per cent. The net summary of these values by the ministry scores the Waihou as New Zealand’s third-most-polluted river.
During last year’s election campaign, Greens co-leader Russel Norman described the river as “solid brown, full of sediment and dotted with great mats of weed”, following a trip from the headwaters to Paeroa. In response, local farmer Stuart King drank several glasses from the Te Aroha boat ramp.
The headwaters of the Waihou River around Matamata are rated by Fish & Game New Zealand as excellent for fly-fishing, one of five sites chosen for the World Fly Fishing Championship in 2008. Such is the population of smaller rainbow and brown trout that there’s no limit on the number that may be caught, as long as they’re less than 30 centimetres. In the sluggish lower river, they say that large trout may be caught by spinner. But what of the fish in the firth where all the sediment and excess nutrients end up?
Near the mouth of the Piako, I saw a sign advertising fresh fish. ‘Piako Pete’, otherwise known as Peter Thorburn, and his wife Gail were just shutting up their small shop and finishing hosing the boat when I turned up on dark. They’ve lived here 30 years and been flounder fishing full time for 17, part time before that. Thorburn owns seven tonnes of flounder quota and sets his nets in 1.5 metres of water, 800 metres from shore.
“The rivers are a lot cleaner than they were 20 years ago,” he tells me. “You used to find dead cows and bale wrap floating downstream and that doesn’t happen now. The Kerepehi dairy factory used to be the main contaminator of the Piako, but since it closed, things have become much better.”*
Rex Smith, who owns one of the five flounder boats working from Waitakaruru, agrees. He started fishing in 1974 and has kept a diary of how many fish he’s caught each month. He fishes for flounder from Kaiaua to the Waihou, particularly over summer when they come up into the estuaries.
“The firth is as good as it’s ever been,” he says. “I’ve had some brilliant years where I’ve caught 50 per cent more fish than normal, and some duds where I’ve only done half as well. But regardless, every year I fish 120 to 130 days.”
Despite the fishermen’s assurances, a stock assessment from 2005 based on catch effort suggested that flounder stocks in the firth were slowly declining.
In April, I headed out of Te Kouma Harbour aboard a Ministry for Primary Industries six-metre patrol boat to see for myself. On board was skipper George Ririnui and two honorary fishery officers, Steve and Karen, who give up their time to assist in policing the firth fishery. Once we approached recreational fishing boats, I could see why they were needed. While Ririnui manoeuvred our boat alongside, one of the officers jumped across on to the other boats to check their catch. A few boats had undersized fish and were given warnings, and one vessel had 19 snapper between only two fishermen, a breach of the seven-fish-per-person rule.
“One of our wives was out here and caught some, but we took her back ashore,” the fishermen claimed. They later admitted there was no wife, and each got an infringement notice that would cost them $250. We checked 25 boats on a weekday in just one corner of the firth, but on a fine summer weekend, there will be hundreds of boats fishing here.
Recreational fishers I spoke with said the snapper fishery was in good shape—far more fish than on the eastern side of the Coromandel Peninsula. Yet like the views of the commercial fishers, these anecdotes don’t appear to match official assessments.
Fishing has reduced the biomass of snapper populations in the Hauraki Gulf by more than 80 per cent. It has also altered their size and age, with populations now dominated by small and young fish, with few large old individuals. Stocks improved a little from the historic low in 1988, but reduced again from 2000 and remain well below the target for a sustainable fishery (40 per cent of pre-fished level).
However, the firth is an atypical area of the Hauraki Gulf in many respects, and may support populations that are greater than the average. Trawling is banned here, there’s little longlining, and the main commercial finfishing targets flounder rather than snapper.
Not far from where we float in Wilson Bay, black mussel buoys bob in the swell. The new aquaculture area slated for this coast includes 300 hectares for finfish farming. While debris accumulates on the seafloor under mussel farms, it’s mostly shelly and not regarded as too serious a problem. But finfish farming may be another story. Some of the pellets fed to caged fish inevitably end up on the seafloor beneath the cage, as do fish droppings, adding around 60 kilograms of nitrogen per tonne of fish produced.
Too much decaying organic matter can deplete oxygen, creating toxic anoxic zones that may extend out beyond the cage footprint for 50–100 metres, depending on currents. Again, mussels farmed in close proximity may offset some of this impact (harvesting of 10 tonnes of mussels will remove the same amount of nitrogen as added by the growth of one tonne of fish), but these local-scale effects require more research.
The fish-farm plan has some critics. Bill Brownell is a quiet, elderly American living near Kaiaua who has a long history with mussel farming and a passion for the environment. He is a fishery biologist and retired United Nations fishery development specialist, and edited Muddy Feet—Firth of Thames Ramsar site update 2004, an examination and collation of all that was known about the southern end of the firth.
“I don’t like the way economic and political considerations drive decision making,” he says. “This push to expand aquaculture in the firth worries me. Already in the Wilson Bay area there are too many mussels, meaning they take twice as long to fatten because they deplete the plankton locally. And the finfish are a particular concern because they add a lot of nutrients to a system that NIWA considers may already be on the tipping point of eutrophication.”
The ‘tipping point’ condition is considered in many ecological studies, usually marking a moment at which the nutrient load exceeds the capacity of a system to assimilate or disperse pollutants, and sudden changes occur, such as an algal bloom that depletes oxygen and kills marine life. However, marine systems are complex, and simple calculations of input and output are confounded by other variables such as currents, weather, solar radiation and precipitation on land. If a tipping point exists for the firth, it’s unclear what that might be, or even what the consequence of reaching it might entail. Scientific uncertainties such as this provide fuel to both poles of the argument—some suggesting that insufficient data implies flaky science, others pointing to a doomsday scenario on just the other side of this theoretical horizon.
The truth is that the firth may have been balancing on this tipping point for much of its history.
Before humans arrived on the plains, it was already a turbulent place. In the past 6500 years, the rivers of the plains have carried down so much volcanic debris from the many eruptions in the Bay of Plenty-to-Egmont zone that the southern shoreline of the firth has moved north by 14 kilometres. Given that volcanic ejecta is rich in minerals—including nitrogen from nitric acid produced in eruptions—leached minerals could have enriched the firth for millennia.
Similarly in the 1860s, gold mining started along the Coromandel and Kaimai Ranges, dumping unwanted overburden and crushed rock into streams. So much sediment built up in the Paeroa region that the town regularly flooded. The forests were sometimes burned to make prospecting easier and to raise steam for stamper batteries, and both activities promoted erosion. One recent paper estimates that 44 million cubic metres of mud was deposited into the southern firth over the 36-year period to 1918, equivalent to around 280 years of present-day sediment loads.
Dairy farming is the latest in a series of challenges thrown at the firth, and most likely not the worst. The increased flow of nutrients into marine systems can sometimes render short-term increases in productivity and fishery yields. Phytoplankton production depends on sunlight and small amounts of nutrients—including iron, nitrogen and phosphorous—which drives the whole food chain in coastal waters. More nutrients, more productive seas, to a point. The firth is attractive to wading birds, fish and shellfish because of its nutrient-rich seas, but it can be detrimental in the long term because of the potential for eutrophication, acidification and anoxia. Is there a better, more sustainable model for development on land and sea?
Around most of the country, you can recognise the tanker entrance to a dairy farm by a little blue-and-green plate with a Fonterra supplier number on it. Towards Tatuanui, plenty of maroon Tatua signs appear, and south-east of that, a smattering of Open Country Dairy signs as well. But then there were a few marked ‘DGC’. Most of the properties had large sheds, and outside, a yard of goats… It’s dairying, but not as you know it.
Wayne and Robyn Montague milk 850 goats plus 200 replacements near Walton. They supply milk to the Hamilton-based Dairy Goat Co-operative (DGC), which has grown from modest beginnings in the mid-1980s to turn over $150 million last year. It has 69 supplying shareholders and plenty more eager to join—unlike Fonterra’s fluctuating payout for milk solids ($8.70/kilogram last year, perhaps $4.70 or less this year), the DGC pays $18.50. The payout doesn’t vary like cows’ milk because goats’ milk is not a commodity.
The Montagues get 100 kilograms of milk solids per doe per year, and goats have a productive life of eight or nine years.
“Goats are intelligent and inquisitive, nice to work with,” Wayne Montague tells me. “But they don’t like rain or storms, stress or parasitic worms, so we keep them indoors.”
Like most goat farmers, the Montagues run a ‘cut and carry’ operation, mowing the grass on their 60 hectares and bringing it to the animals. The downside of indoor farming is that you have to keep the floor litter dry, which means regularly replacing it, but used shavings can be spread back on the paddocks, and there’s less effluent output from goats than cows, minimising some of the environmental problems—no pugging damage to paddocks, little sediment, less nitrogen, less E. coli in run-off.
Goats can suffer from caprine arthritis encephalitis, an incurable disease that causes swollen joints and wasting, making management of the herd during kidding particularly difficult, so this alternative isn’t without problems. Sheep milk has similar environmental advantages over cows’ milk. It’s higher in protein and minerals than cows’ milk—even goats’ milk—and better digested by people who are lactose intolerant, which includes half those of Asian descent. There’s already a dairy-sheep operation in Southland with 25,000 sheep, and other ‘boutique’ enterprises trading in fashionable rural areas such as Waiheke Island.
Despite government priorities to double the value of agricultural production by 2025, lower returns for milk could force farmers to consider alternatives such as these, or return to the less-intensive version of dairying that prevailed until 25 years ago.
At that time, legume clover was fostered to fix atmospheric nitrogen in a plant-available form, rather than spreading nitrogen fertiliser. This low-input model had a correspondingly lower output, but costs were dramatically lower too.
One doesn’t have to venture far to see a future that borrows from the past. In Ngatea, between kilometres of dairy farms, is a new model of sustainable farming… or, rather, a much older model.
On a blustery spring morning, I visited a three-hectare farm belonging to the Supported Life Style Hauraki Trust, which provides a ‘whole of life’ 24-hour service for people with special needs and severe brain injuries—there are 60 in its care. Most of the ‘life stylers’ live in homes in Thames, where a cafe serves as a focus for their activities. The farm—which has been operating for 12 years—produces much of the food for the cafe, and is a place for the life stylers to work and learn basic skills. All the waste comes back to the farm and is composted, along with manure that is collected from the animals.
Old mower catchers serve as egg-laying boxes for chickens and ducks. Silverbeet, broccoli, cabbage, potatoes (1.5 tonnes last year), tomatoes, beans, pumpkins, apples, pears, plums, nashi, and quince all flourish. Larger trees provide firewood. Strewn among sheds, gardens and small paddocks are Muscovy ducks, half a dozen cattle, three breeding sows plus a boar, a few donkeys, sheep and horses.
In its own way, this mixed farmlet is probably more intensively farmed than most dairy farms, and its diversified products more valuable. While it’s not built on a commercial model, it harks back to an earlier time when farms were smaller and more diverse. Like in my mother’s days on these plains, when cream was taken down the river on a launch to the factory, when the farms were embedded in the communities they supported, and when the communities supported the farms—the sort of rural idyll that many still yearn for today, selling carefully grown food through farmers’ markets and roadside stalls.
It’s interesting to think that a return to the past might be a progressive alternative. Or that a low-input model might be more rewarding than a high-input one. Or that sheep—on which the foundation of farming in New Zealand was built—might offer opportunities for the future of dairy. Whatever the case, as the market for milk ebbs and flows, the running calculation of natural cost and commercial benefit will remain on everyone’s minds.