The majority of the Bay of Plenty's water ways, including those which run through farmland, have good stable water quality. That's the message from the senior policy advisor For Federated Farmers, Elizabeth McGruddy.

Measured against a range of tests, which included those for nitrate and phosphorus, water clarity plus swimming quality, around 80 per cent of region's freshwater sources are of good or high quality.

Elizabeth McGruddy, senior policy advisor For Federated Farmers. Photo: Supplied.

The news was delivered at yesterday's Bay of Plenty Federated Farmers' annual conference in Edgecumbe.

The conclusion put the region in a strong position as it works towards meeting the conditions of the Nation Policy Statement for Fresh Water Management, which requires regional councils to establish freshwater objectives and to set water quality and quantity limits for all bodies of freshwater.

'In this region it's an 80-20 game and there's a need to prioritise the ‘hot spots',” says Elizabeth.

'Drill back to understand the patterns and drivers (of problems). Go back up the catchment, go back in time, and use local knowledge to understand what's happening.

'The Bay of Plenty Regional Council has done a good piece of work on the Rangitaiki waterways. It has data going back to the 1970s and 1980s which show the aquatic life in the waterways has been stable.”

Council's 2014 report on the ecological assessment of the Rangitaiki waterways says in part: 'The finding of so many streams either good or excellent was surprising, especially given that 83 were in catchments dominated by exotic forest or pasture”.

Pasture streams flowing through productive farmland on the Galatea Plains in particular had good ecological conditions. Of 10 streams, four were excellent and six were good.

Elizabeth says data produced last year from 29 monitored sites in rivers, 20 sites in lakes and 15 from coastal sites showed 64 per cent of rivers and 95 per cent of lake and coastal sites had water quality suitable for swimming.

She also quoted a DairyNZ report which says trends in the Bay of Plenty highlight stable or improving water quality across most indicators.

Tauranga waterways are largely stable or improving, except for an increase in phosphorus in most sites, especially at Omanawa.

All six monitored sites in the western region are also stable or improving in quality except the Puarenga Steam at Rotorua.

In the eastern central region, seven monitored sites are stable or improving except the Rangitaiki at Murupara and the Tarawera at Boyce Park. All five of the eastern region sites are stable or improving.

All too often, farming is blamed for poor water quality, but Elizabeth says experience in other regions shows water quality problem 'hotspots” often have other causes.

'In the case of the Parkvale Stream in Taranaki, a nitrogen hot spot was identified as a legacy of a freezing works, and levels are now dissipating,” she adds.

Clearing of willows from along the Kopuaranga River in the Waiarapa and a drought in 2008 was shown to be the cause of increased algal growth in the river.

Similarly the removal of crack willows from along the Taueru River lead to increased sediment in the waterway.

When it comes to deciding on the water quality in individual regions, Elizabeth says it's about finding a working balance between the wishes of local communities, requirements of aquatic life, recreational use of waterways and the needs of farming and irrigators.