An explosion of agriculture and exponential expansion of irrigation schemes, which led to an increase in effluent and fertiliser run-off had poisoned the rivers, killed the fish, and contaminated it to the point that it was hazardous to human health.

Years later, after a successful campaign on river health and water quality run by prime minister Jacinda Ardern, New Zealand's rivers are coming back to life, but it took significant reform and a complete overhaul of the system to get there.

New Zealand water ecologist and councillor Lan Pham, who also platformed her local government re-election on water equality, said reform for water management and environment now placed environment as the number one surety for New Zealand water.

The legislation is based on Te Mana o te Wai, a Maori concept that is integral to the management of freshwater and tries to capture the vital importance of water in NZ.

Ms Pham said there were striking parallels between the ambitious goals of the previous government in New Zealand, who pursued growth in agriculture, particularly in the Canterbury region, with the goals of the Tasmanian Liberal Government.

The Canterbury become what was known as "ground zero" of the reforms, as it was home to some of the most polluted rivers in New Zealand. It was also where there was the most intensive agriculture and largest irrigation schemes.

"The more I learned, the more alarmed I became....it was 150+ years of over-development but had particularly accelerated in the last two to three decades," she said.

Rivers were known to be unswimmable, and the cost to human health has not been fully realised, and more is being uncovered about health impacts in New Zealand.

"There are studies going around now that are showing a link between high nitrate levels in water and pre-term births in pregnant women," she said.

Nitrate is the main chemical found in fertiliser used in agricultural production and it can build up to dangerous levels when it's washed from the topsoil into the environment.

A teaspoon of nitrate-polluted waters in the Canterbury region could kill a dog, and it would leave a human with nausea and gastro-intestinal problems for about 24 hours.

The World Health Organisation has a "safe level" of nitrates in drinking water of 11.3 mg/L but research into the drinking water in New Zealand, including at Christchurch, has shown the levels are far higher than that. The latest research conducted in New Zealand has shown health impacts can be recorded in levels as low as 0.8mg/l.

Dr Mike Joy, who has been leading the research into the pollution of New Zealand's rivers, posted a research paper in May that showed there was not enough rain and river water in Canterbury to dilute nitrate pollution from dairy farming to acceptable drinking water standards. The study showed every litre of milk produced in the region needed up to 11,000 litres of water to dilute the pollution from its production.

In Tasmania, dairy farming makes up the largest portion of the state's agricultural industry, and it's the most profitable. The Tasmanian Government also has a bold target to increase the farm gate value of Tasmania's agricultural industry to $10 billion by 2050.

Tasmania is also home to the largest and oldest dairy company in Australia - Van Dairy, formerly known as Van Diemens Land Company.

Tasmanian Irrigation operates 16 schemes in Tasmania, with another five planned or in various stages of production, and there's a number of legacy extraction licences.

These conditions have placed pressure on Tasmania's river systems, with an internal report from the Department of Natural Resources Tasmania showing that nearly half of the state's rivers had experienced a level of ecological decline.

It has also shone a light on Tasmania's water management, which is governed by NRE Tasmania, through a new strategy - the Rural Water Use Strategy that aims to bring together "sustainable management" of Tasmania's freshwater resources and align them with goals such as those of AgriVision 2050.

Academics and water ecologist have shared their concerns that expansion along these lines will place too much pressure on Tasmania's water resources, as increased competition from projects such as the Battery of the Nation and the green hydrogen industry will lead to catastrophic environmental decline.

Ms Pham cautioned Tasmanian leaders on following this path, without proper consideration of the environment, which is fundamental to human health.

In Tasmania, there are eight hierarchical surety levels for the taking of water in Tasmania. Drinking water and for domestic use (including livestock) is number one.

The second is water provision for the needs of ecosystems that rely on water. The third is commercial water licences issued for a minimum of 99 years. Fourth is for licencees such as Hydro Tasmania. Surety 6 is rights for direct extraction, which includes for irrigation storage in dams or other commercial purposes.

However, in New Zealand the environment takes precedence over everything, in consultation with the Maori populations in each area.

An orange-coloured river flows through the heart of one of Tasmania's wettest areas - the rugged and wild West Coast.

The Queen River was used as the tailings dam for the Mt Lyell Copper Mine for decades, and it led to total ecosystem collapse of the river system. All the fish and macro-invertebrates were killed and the water now runs vibrant orange.

Despite many years and many attempts to rehabilitate it, the river remains a burnt-orange, coloured by past uses and the orange clay that it picks up from the river's edge.

West Coast mayor Shane Pitt said the Queen River had become an icon of the region, and brought tourists and influencers looking to get an Insta-worthy shot of the river.

"For us it brings more people into the town than anything," he said.

In previous years, the council, prior to the formation of TasWater, which divested local government of water management responsibility, had investigated options to try to rehabilitate the river, but no work was being done currently.

"From our perspective, it's probably more a state government responsibility," he said.

However, he said there were attempts also over the years to establish a research hub in collaboration with UTAS as an opportunity for their students to work on a landmark project to rehabilitate the river.

"It will take 100 years to rehabilitate the river," he said.

He said it was a legacy of the past that the region had to bear, and if he had a crystal ball, of course he would want to minimise the impacts.

However, he said the region had also benefited from the tourism the river brings in, such as the Unconformity Festival, which has the river as its unofficial mascot.

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