The report, released by Environment Canterbury yesterday, had Waitaki worst of the 10 Canterbury districts with only 50% of farmers fully complying with resource consents and permits and Waimate only slightly better in eighth place with 54.4%.
By comparison, the Ashburton district topped the table with 75.1% - and it also has the highest number of dairy farms of any Canterbury district.
The compliance monitoring is carried out annually during unannounced visits to assess the environmental performance of dairy farms. In the latest 2010-11 report, 917 dairy farms of the 921 in Canterbury were visited and 65% were found to be complying fully.
The Waitaki figures are for 18 dairy farms operating in the lower reaches of the Waitaki Plains (east of Duntroon) which fall in Environment Canterbury's (ECan) region. While bottom of the list, Waitaki's 50% was a big improvement over the 24% fully complying in the previous season.
North Otago Federated Farmers president Richard Strowger, when contacted to comment on the latest results, said the figures were difficult to judge without knowing exactly what was being monitored and how minor or serious breaches were - they could simply involve administration slipups, for instance.
"It does not necessarily mean farmers are putting effluent into rivers and streams."
He also said rules had changed remarkably in the last few years and interpretations or understanding of those by farmers and ECan could differ.
The monitoring report showed compliance for the whole Canterbury region had improved from 59% in the 2009-10 season to 65% in the latest report. Waitaki Plains farms had also improved.
Mr Strowger said this showed farmers were "getting the message". It also meant farmers were gaining a greater understanding of the changing requirements and rules.
The report showed the most common cause of non-compliance by far was ponding of effluent (84%).
Other major non-compliance items were applied effluent not being absorbed because of soil depth or exceeding the water-holding capacity of soils (17%), exceeding herd sizes (7%), overflow from effluent storage (6%) and discharges outside the disposal field (4%).
ECan commissioner Tom Lambie said the monitoring report was an important means of assessing the environmental performance of Canterbury dairy farms.