NRC inspectors also visited 206 non-consented farms and saw an increase in significant non-compliance from 20 per cent to 26 per cent while non-compliance went up from 6 per cent to 9 per cent.
Full compliance was down 9 per cent in 2016 compared with the previous year.
NRC issued 55 abatement notices and 39 infringement notices last October for farm dairy effluent discharges.
Untreated effluent discharges to water and inadequate management such as broken pipes and sump overflow topped the reasons for significant non-compliance for consented discharges.
Others factors included excessive ponding, overland flow, and required upgrade not completed by due date.
Excessive ponding mostly contributed to significant non-compliance for non-consented discharges.
Farmers of New Zealand and Federated Farmers have called for more clarity in terms of what constituted significant non-compliance as the public may assume the worst.
"The NRC has the toughest regime in the country and so most people assume significant non-compliance means a serious impact on water quality but that's not true," said Ian Walker, Farmers of New Zealand president and a Kaitaia dairy farmer.
"Does a significant amount of dairy effluent constitute significant non-compliance or just a few splashes? That's what needs to be redefined."
"I don't have an issue with the higher standards set by NRC when it comes to management of effluent but let's not paint Northland dairy farmers as environment vandals," Mr Walker said.
He said when he was a regional councillor, he kept arguing for consistency in the definition of breaches but said the status quo remained.
Federated Farmers Northland dairy chairman, Ashley Cullen, said sometimes NRC inspectors got a "little bit pedantic" when defining the extent of breaches on farms.
"Ponds could be well done but they are not irrigating as per a condition in the resource consent. Now that's classified as significant non-compliant."
NRC chairman Bill Shepherd said farmers who breached the terms of their resource consent were given an opportunity to remedy the situation rather than being issued with infringement or abatement notices.
"Non-compliance or significant non-compliance meant farmers did not comply at the point of inspection. It certainly does not say they continue to be bad performers," Mr Shepherd said.
He said there could be a number of reasons for an increase in non-compliance, including a fairly wet spring, but said farmers needed to start complying with rules.
In October, Beejay Stud and Clear Ridge Station, which own farms in Kaipara, were fined a total of $225,000 for discharging dairy farm effluent on to land and contravening abatement notices.