Taupo farmers who operate under restrictions which aim to improve the water quality of the lake, are outlining how their farms have been affected.
Taupo catchment farms are the only ones in the country to operate under a nutrient discharge cap, which controls the nitrogen leaching into the lake, usually in the form of effluent and fertiliser runoff.
Waikato Regional Council enacted that policy, known as Variation Five, nearly a decade ago and Beef + Lamb New Zealand set up a monitor farm four years ago.
Beef + Lamb is unveiling that data on Thursday to help policy makers decide whether the Taupo catchment model could be used in other regions.
Extension manager Erica van Reenan says it's too soon to say whether the lake is cleaner because groundwater can take 40 years to work itself into the lake.
But she says farmers have noticed the difference and there have been challenges with this, such as negative effects on land values.
''Most farmers have had to reduce their stocking rates, but they are becoming more efficient producers,'' she said.