A new documentary, showing in this year's New Zealand International Film Festival and opening in Auckland tonight, tells the tale of seven rivers in the Canterbury Plains - and the industrial pressures that are driving their decline.
But Seven Rivers Walking - Haere Marire - featuring farmers, anglers, rafters, trampers, mana whenua, conservationists and natural scientists - also speaks to the wider problem of freshwater quality in New Zealand, a charged issue this election.
"In the polarised political environment of 2017, this film is a disarmingly peaceable one," said the festival's founding director, Bill Gosden.
"It places the hope of change in a shared love of our rivers and riparian environments and a profound appreciation of their ecology."
Science reporter Jamie Morton discussed the film with its co-directors, Gaylene Barnes and Kathleen Gallagher, who set out to witness the plight of Canterbury's rivers for themselves.
Tell us a little about this film and why you felt compelled to make it.,
There is a large group of people in Canterbury very passionate about their rivers, and very active.
We took our cue from this community, and their actions.
They wanted to walk their rivers to raise awareness.
We followed these folk as they explored seven Canterbury rivers, including two alpine braided rivers, the Rakaia and the Waimakariri, three hill rivers, the Ashley/Rakahuri, the Orari, and the Upper Selywn/Waikirikiri, and the spring-fed rivers on the "mudflats" - the Heathcote/Opawaho, the Avon/Otakaro, and of course the lower Selwyn at Coes Ford - which is also spring-fed from the big rivers.
The energy, joy and enthusiasm of the walkers and rafters and the wonderful children we met along the way - the guardians, the kaitiaki of our rivers, inspired us onwards and upwards.
One of our characters, Mike Glover, makes a good point early in the film: "Once you start doing stuff for the river, the river's got you now."
This happened to us.
This film is for our children and our grandchildren and great-grandchildren - so they know how our rivers once were.
We thought things were bad with our rivers, but once we started researching and digging around in January and February, we realised that our rivers are in total crisis, and heading unrelentingly in an even worse direction.
What challenges did you encounter in trying to tell the story - and how difficult was it attempting to explain the politics and complexities underlying the issue, particularly in Canterbury's context?
It was important for us to put the weight in the film on the things that truly matter about our rivers.
What it is that people really cherish about their rivers.
Their water, their beauty, the fish, the birds, the plants and all the life that inhabits the rivers and their edges.
There are a pile of troubles that plague our poisoned, depleted and degraded rivers.
Opawaho/Heathcote has been heavily polluted with chemicals sediment and rubbish dumping for years, so folk fished and swam further and further out from the cities - Selwyn/Waikirikiri, then Rakaia and the Orari.
Now, every single one of these rivers is polluted and many are over-allocated - we need to take a step back and look at them all and then take a step forward and clean them all up.
The best way we found to deal with it was to toss them all together into one rather grim five-six minute sequence - that ends with an apt observation from Rakaia Huts local Bill Southward who said: "Jesus, what a mess we've got."
A big challenge was to take care not to point the finger too long at any one group in particular - the restoration of the health of the rivers is a job for everybody.
We need everybody to come onboard, acknowledge there is a problem and work together towards a solution.
To look very closely at our own rivers and how we can restore it to its health and wellbeing so once again our rivers are full of wildlife and swimmable and drinkable by all.
The degradation of rivers we've seen in Canterbury - particularly the Selwyn - have been particularly pronounced. What were some of the most heartbreaking sights and findings you came upon?
Watching dozens of people taking a day off their jobs to rescue dying tiny fish and eels from a river depleted of water.
At Coes Ford, dairy cows were stumbling over large boulders, stones and mud on the shingly soil of the north banks of the Rakaia river.
It's also the smell - the odour of the fodder-beet paddocks laced with nitrogen-laden urine, where the cows or steers have been ruminating all winter, in the same spot.
Knowing that this is being repeated all across the vulnerable soils of the Canterbury Plains as 30 to 40 million litres of urine a day is being washed into our waterways.
At the source of the Opawaho/Heathcote, we found ammonia, sulphur, then further down, huge sediment runoff via the Cashmere Stream, and then plastic and rubbish on the banks of the river.
The Lower Orari, which Kathleen had thought swimmable and pristine, was full of black algae and other poisons from nitrate pollution, so is no longer swimmable.
The mid Ashley/Rakahuri, which Kathleen had also thought was okay, was full of weeds everywhere so birds couldn't safely nest, and there was very little water, because the river was severely over-allocated and affected by nitrate pollution.
We were surprised at the amount of river water over-allocated by ECAN from most of the Canterbury rivers.
How much concern do you think now exists among the New Zealand public about the state of our freshwater environment?
There is a huge amount of concern - more than 800 people were at our opening launch at the Lady Isaac Theatre Royal in Christchurch.
It was the top-selling single screen film of the New Zealand International Film Festival - and this is because people care about their rivers in New Zealand.
We've heard Environment Minister Dr Nick Smith reject any notion of freshwater issues being a simplistic case of "good guys vs bad guys" - or environmental groups against industry, if you like - and that, through good science and management, it's possible to have a strong primary industry and healthy waterways. Do you think the picture is much more nuanced than the narrative most of us get - or this still just a classic case of economy vs environment?
The "science" voice - that voice pointing out the hazards and threats to the river and its eco-system - is not being listened to.
Despite all the rhetoric from the National Government and industry about being committed to "make decisions based on evidence-based research", it is quite clear that the decisions being made are favouring economic imperatives, particularly with regards to the dairy industry.
They do not want to upset the apple cart, because those apples are piled up really high and very precariously.
Also, some of the "management" solutions being proposed are just furthering a weird irrationality that currently pesters water management.
For instance, take a look at the problem of the over-allocated groundwater-takes for irrigation.
This is causing the groundwater levels in the aquifer to drop, creating further problems down-stream as the spring-fed Christchurch streams start drying up.
A rational person, looking at the "evidence" and taking into account what the groundwater scientists are saying would suggest that this problem was best solved by immediately reducing groundwater takes.
Instead, the Government advocates that this problem will be solved by a big engineering project such as the Central Plains Water Scheme (CPWS), whose high concept is to introduce a "sustainable" run-of-river supply from the "surplus water" of the Rakaia River.
What is actually happening, of course, is that only some farmers are forfeiting their groundwater takes in favour of the CPWS, because it's a lot more expensive, and less reliable.
And we now have a lot of new shingly land being converted from drylands to irrigated land.
Thus, we are not solving the problem at all, but simply creating another one.
One of our characters says: "If you're getting into trouble, just go back and look at your basics and see where you went wrong."
A fundamental basic is that the river recharges the groundwater.
So it is irrational to take water away from the internationally significant braided Rakaia River to store it in Lake Coleridge to sell to irrigators at 8c per cubic metre, to divert it into numerous channels, to suck it out of numerous surface-takes all along the length of the river - and to deplete the stunning Rakaia River so much that it now leaks and limps its way to the coast.
Another example of irrationality is the claim that the CPWS will somehow "flood the plains" with all this water from the river, which will help to recharge all the lowland streams.
But then they say that the irrigators will use the water so "efficiently that the plants will only get what it needs".
This is double-speak, plain and simple.
We now have scientists concerned because the irrigators are not so leaky anymore, as the old leaky drains and dykes were contributing to recharging the groundwater in the past.
The solution proposed at the moment, and to which the Government is to contribute $1.2m, is to "recharge" Coes Ford with another big engineering project called Managed Aquifer Recharge.
Apparently, they want to build dozens of these purpose built "leaky" lakes all over the plains.
Let's get back to basics - the river recharges the aquifer.
We need to reduce surface-water takes and reduce groundwater-takes, immediately.
And the nitrate leaching problem?
Don't get us started on the "management" solution they tried a couple of years ago, DCD, a nasty antibiotic they threw around to kill the nitrifying bacteria in the soil that converts ammonia to nitrate.
The Chinese consumer wasn't too happy to find that in their milk supply.
I would say that if this is the sort of science and management that Environment Minister Nick Smith and Denis O'Rourke, the Central Plains Water Trust chairman and New Zealand First candidate, are going to continue to advocate, then we will not be able to increase the primary industry any further and also have a healthy environment.
So it is actually a classic case of "economy vs environment" situation, because Nick Smith and his posse will continue to cherry-pick the science that aligns with their economic imperative, over the real basic needs of the natural world.
The dairy industry is deeply indebted, mono-cultural and unsustainable.
It is feeding the long term wealth - not of farmers - but of banks, fertiliser companies and irrigation construction companies.
It is not feeding the long-term health of our soils and waterways.
It could be.
A healthy primary industry sector needs to be diverse, resilient and regenerative.
The pre-dominant farming practices of today make it difficult for the microbes which cleanse and heal our soils and aquifers to flourish.
Round Up and other pesticides and poisons routinely used in farms and in our gardens and sold in supermarkets, kill microbes and destroy the microbial community.
This is what the health of our soil, and therefore our water depend on.
The science and management we need should be built on the biodiversity of plants and livestock.
We want healthy resilient farms regenerating the soil, leaving the soil and our waterways better than we found it.
From what you've learned through making this film, do you hold any real hope that we are going to be able to restore polluted and degraded waterways back to the way they were? And, if so, what do you feel we need to do to get there?
Yes, we can immediately take action to restore our waterways to better health.
The farmers and local iwi around Raglan Harbour have already done just that.
Environment Waikato told them it would take 70 years to turn it around - it took them 10 years.
Not only are the rivers and harbour once again swimmable and fishable, but the farms themselves are loaded with fish.
To have a healthy waterway, all water-take consents need to be all revisited and reduced, fairly, across the board.
Water Conservation Orders must be respected and the minimum flows should not be regarded as a bottom-line.
The larger rivers need riparian strips of at least 50m on each side - folk can use it for walking and cycling, and wildlife and plants can delight in these precious strips.
Every stream and creek and pond needs a riparian strip on each side of it.
We need to increase wetlands by digging holes and creating waterholes rich in a diversity of species, as these are the places where nitrates are naturally converted back into dinitrogen in the air.
Farmers and gardeners need to celebrate and embrace the bio-diverse deep root systems of pastures - plantain, alfalfa, chicory and herbs - which protect microbes that work beneath the soil, cleansing and purifying the soil and the water.
Around each plant root live 100 times the amount of microbes as live in other unplanted soil.
They used to describe "the energy" in this place when they talked about Aotearoa New Zealand in the 1840s.
It felt like the bush and the whole place was alive - it was and is full of microbial life.
The grazing patterns need to be altered so deep rooting plants prosper and the number of cows per hectare reduced from three or four per hectare, to two or fewer per hectare.
Spawning grounds on every river lake and stream need to be protected with riparian plantings and growth all around them, with no fishing in any if them.
Councils need to enforce heavy penalties for polluters - that includes those who dump sulphur, ammonia, nitrates, chemicals and other poisons on the land, and all developers or foresters who allow sediment runoff into our waterways.
We need to reduce our use of inputs on farm significantly - such as synthetic fertilisers and palm kernel extract feeds.
According to the World Bank, New Zealand has a fertiliser use up there with Bahrain - a desert - and Singapore.
If we cannot sustain our herds on-farm, then we do not have a sustainable farming system - no matter what good management practices are in place.
We would like to see all imports of urea and superphosphate banned - these are the main drivers pushing us straight into a polluted paradise.
Every community can do it and can also be assisted by Government - national and local.
When it boils down to it, what's the take-home message of this film?
Walk your river, learn about your river, connect with your river.
Know your river and learn what your river needs.
Work with a local group to restore the health of your river.
Look at every policy involving water - demand that our local and national governments stop the plundering and pollution of all our waterways immediately.
Join Forest & Bird.
Plant trees and deep rooting herbs and plants.
Basically, the film offers the potential to be "smaller, gentler and slower" in our moves upon the planet - rather than the modus operandi of "bigger, harder, faster".
In general, if we all were to have a more profound sense of the diverse life that abounds around us, we would all take greater care.
• Seven Rivers Walking - Haere Marire opens in Auckland tonight at 7.30pm at Event Cinemas on Queen St, with the festival season also opening at Rialto Newmarket from tonight at Rialto Newmarket.