Hurrell said farmers had spent more than $1 billion in fencing off water waterways and on riparian planting over the last five years.
With 98 per cent of significant waterways now fenced off, farmers were continuing to spend big money on installing effluent systems and on improving the way they irrigate and fertilise their properties, he said.
Fonterra said it would spend $250 million at its 26 manufacturing sites with the aim of reducing water consumption by 20 per cent.
It would also double the number of advisers to help farmers develop a tailored farm environment plan.
The co-operative has already announced a plan to restore 50 key water catchments across New Zealand and has launched a new programme to find new solutions for sustainable farming and healthy waterways.
On December 10, 40 farms will open their gates around New Zealand to the public in what Hurrell said would be the biggest event of its type by Fonterra.
The co-operative's latest action follows a series of less than flattering reports on the state of New Zealand's rivers.
A recent article in London's Economist blamed cows for making 60 per cent of the country's rivers and lakes unswimmable.
In April, a Ministry for the Environment report said nitrogen levels were getting worse at more than half the monitored river sites across New Zealand, and were improving at more than a quarter of them. Secretary for the Environment Vicky Robertson said at the time land use "clearly affected" the state of fresh water in this country.
In addition, an OECD report said New Zealand lacked a long-term vision to address the worsening problems of water pollution, dying wildlife and disproportionately high greenhouse gas emissions.
Fish & Game's chief executive Martin Taylor said the latest moves by Fonterra were aimed at regaining its social "licence to operate".
Taylor said Fonterra had now realised it must act quickly to meet public demand for better water quality.
"Fonterra has been around for 16 years and in that time we have seen cow numbers soar, irrigation explode and water quality plummet," Taylor said.
"Public anger is now at a level where Fonterra's social licence to operate is under serious threat and they're being forced to respond," he said.
"Every New Zealander is now watching how Fonterra will fulfil its environmental promises," Taylor said.
"It needs to act quickly and decisively to prove its commitment is real and not just public relations spin."