Seventy-nine per cent of all dairy shed inspections from 2015-16 were determined to be complying - an 8 per cent improvement over the previous year, the council said. There are about 700 consented dairy sheds across the region.
But there were more than double the number of significant non-compliances, said council regulatory compliance manager Nick Zaman.
There were 15 significant non-compliance episodes for the 2015-16 period compared with seven for the previous period. However, the council notes that it did 370 inspections in 2015-16 compared with 290 in 2014-15.
And preliminary inspection results for the 2016-17 period showed a decreased level of significant non-compliance, said Mr Zaman.
"It's worth noting that the majority of these unauthorised discharge events were found through council monitoring, rather than responding to complaints," said Mr Zaman.
The council's compliance report for 2015-16 said that region-wide it had achieved 75 per cent protection along stream margins.
Federated Farmers Bay of Plenty dairy chairman Steve Bailey said that according to its internal monitoring, compliance by dairy farmers was up.
"There have been millions of dollars spent by farmers across the Bay in ensuring they do have good systems in place to manage the effluent portions of their operations," he said.
"Things have moved on with regard to farmer attitudes about this. The good thing is that if discharges have been reported, they've been followed up, so clearly systems are in place."
Bay of Plenty MP Todd Muller, who served as an executive in the dairy and kiwifruit industries before entering Parliament, said there had been a huge change in the dairy sector. But he noted there were still beef and sheep farmers who still had to get to grips with their obligations to keep stock out of waterways.
"We should acknowledge the journey the dairy sector has gone on, but of course it's not yet complete. You're constantly improving your system. Having transparency around that helps keep the pressure on to make sure we get the best result possible."
Green Party water spokeswoman Catherine Delahunty said she supported the efforts of farmers to fence cattle out of waterways, with plantings to soak up phosphorus.
"But it's not the solution. The issue is not effluent ponds - it's too many cows and their urine [with nitrates] leaching through the soil and ending up in waterways. Intensification creates risks right across the system. It remains a concern that we have not yet recognised that to farm smarter, we need to look after waterways better."
Most common dairy farm effluent problems
- Poor pond management.
- Effluent irrigation causing bad ponding and/or runoff to waterways.
- Effluent observed discharging through the stormwater diversion system.