A major milestone has been reached on reducing the amount of nitrogen entering Lake Taupo, mainly from farming.
Lake Taupo Protection Trust has signed contracts with landowners around the lake that will achieve the target of reducing nitrogen leaching by 20 percent or 170 tonnes a year.
An $80 million fund set up to protect the lake has been used to buy land and convert farms to forestry, and help farmers find new ways of farming.
Trust chief executive Graeme Fleming says a 300-hectare farm produced about 3 tonnes of nitrogen per year so to reach the target of 170 tonnes was a real effort.
"We weren't forcing anybody into land changes," said Mr Fleming.
"It was a matter of trying to present the best business case that we could, and for parties to consider that business case and make their own decision.
"I think we were fortunate enough that we had a bit of a tail wind with carbon legislation which enabled the business case for land-change ... seem very viable for parties, so that certainly helped."
Graeme Fleming said 7500 hectares of farmland in the Lake Taupo catchment would be converted to forestry.