Waikato Regional Council says efforts to reduce nitrogen runoff from farms into Lake Taupo are on track.
There are 116 farms in the Lake Taupo catchment, five of which are dairy farms.
Programme manager Natasha Hayward said the target is to reduce the amount of nitrogen getting into the lake by 20%.
She said the target of restoring the lake's water quality to its 2001 standard was likely to take a number of years.
Ms Hayward said while the condition of the lake is excellent by international standards, a steady decline is noticeable because of nitrogen pollution.