Hawke's Bay sheep and beef farmer Bruce Wills, who is also chairman of Apiculture NZ and on the boards of Horticulture NZ, Ravensdown and the Our Land and Water National Science Challenge, said scientific advances were enabling changes that would not have been foreseen in the past few generations.
"With good management and good science, you can achieve economic profit with minimal impact on the environment.
"We are going to solve the problem, the science around managing nutrient losses is very exciting - it will take a little time but we will get there."
Fish & Game chief executive Bryce Johnson welcomed the farmers' pledge "with open arms", but also described it as "frank admission" from the industry that it had "not always got it right."
He acknowledged that farmers had taken some "real steps", like fencing off waterways, to prevent cattle from fouling streams and rivers, and the pledge had put farming leaders in step with the community at large, who were "fed up with dirty rivers that aren't swimmable let alone fishable."
He now wanted to see concrete details from the industry as far as remedial and preventative measures were concerned.
"In other words, the industry putting its money where its mouth is."
Environment Minister Nick Smith said the pledge showed a real commitment from farmers to tackle long term water quality issues.
"Farmers are closer to the land than nearly anyone else, and they care deeply about leaving a good legacy for their children," Dr Smith said
"Most of New Zealand's rivers are in a good state but there are a number that need work, and this will take concerted effort by all New Zealanders - including farmers, urban areas, and local and central Government.
"We need to recognise the massive environmental improvements that farmers have made in recent times. In the last five years it's estimated that farmers have spent over $1 billion of their own money towards environmental measures on farm, with around 98 per cent of dairy waterways fenced off."
Along with Beef + Lamb NZ chairman James Parsons, the other members of the Farming Leaders Group are Dairy NZ chairman Michael Spaans, Meat Industry Association chairman John Loughlin, Central Hawke's Bay sheep and beef farmer Mike Petersen, and Fonterra chairman John Wilson.