Waikato Regional Council is contacting more than 3000 dairy farmers who need resource consents under new water allocation rules.
Variation six, an amendment to the regional plan, was approved late last year after 37 appeals were heard in the Environment Court.
It was first proposed six years ago to manage the allocation and use of fresh water in the Waikato region.
The variation allows dairy farms to take 15 cubic metres of water per day for dairy shed water, anything above that will require a resource consent.
The council says the deadline for farmers to lodge further appeals to the High Court has passed and it's now implementing the plan.
Resource manager Brent Sinclair says some farmers may not know they are affected by the new policy.
Resource consents must be in place by 2015.