Bay of Plenty Regional Council reports a less than auspicious start to its annual round of dairy farm inspections.
Inspectors have visited half of the region's 350 dairy farms so far and found more than 20 with serious breaches of effluent discharge conditions.
Many of these involve unauthorised discharges of effluent to land or waterways.
Regulation Monitoring and Investigation Committee chairman Neil Oppatt, says inspectors have found overflowing effluent ponds, lack of irrigation system maintenance and poor staff training.
Other contamination sources such as leachate from silage pits and effluent run-off from feedpads on farms, have been identified.
He says farmers moving to more intensive farming need to make sure that systems such as feed-pads are properly designed and able to cope with the extra effluent load.