The Waikato Regional Council's Healthy Rivers plan could radically change dairy farming in the region, says Dairy NZ.
The council is working with stakeholders to develop changes to its regional plan in order to restore the health of the Waikato and Waipa rivers.
The changes are likely to set limits to nutrient pollutants that can be lost from farms into waterways.
Getting farmers engaged in the planning process is Dairy NZ's catchment engagement manager Adrian Brocksopp, who says the extent of changes to farming in the Waikato depends on the nutrient limits set in the plan.
"Until we know what the limits are we can't say what's going to happen. We know there are gains we can make as a dairy industry. Some of those gains will be getting people into good management practice.
"We've estimated in the upper Waikato that a five to eight percent reduction in nitrogen has been achievable with the appropriate resources and support."
He said if the reductions for any of the key contaminants like nitrogen phosphate, sediment or E. coli, are greater than that, it may mean farm system change.
"We know from research there are options that farmers can employ to reduce risk at certain times of the year dependent on what contaminant they're trying to control, but it depends on the limits they're trying to meet.
"We've also got to be careful we don't solve one problem and create another. It's not just about reducing a number. It's how does that fit into your farm system while still remaining profitable."
A series of meetings will be held next month in the Waikato to give farmers the chance to have their say on the Healthy River Plan.