Claims were likely to herald the arrival of Armageddon or suggest things aren’t too bad.
Data provided to the Farmers Weekly by regional councils from five key dairy areas showed the truth lay somewhere between, and the use of sweeping generalisation in debates concealed a much more varied picture of the state of New Zealand’s fresh waterways.
Two reports this year from the Ministry for the Environment (MFE) and the Organisation for Economic Co-operation and Development (OECD) warned the country’s waterways were under increasing pressure, or reaching environmental limits.
The MFE report found nitrogen levels were getting worse at 55% of monitored river sites and improving at 28%, while phosphorus levels were improving at 42% and worsening at 25%.
It also found E. coli levels were 22 times higher in urban areas, and 9.5 times higher in pastoral rivers than for rivers in native forests.
Taranaki was proud of progress it had made to improve water quality, attributed to riparian plans covering 14,500km of streams, of which 85% were fenced and most planted.
Taranaki Regional Council environment quality director Gary Bedford said the council measured water quality based on its ecological health by using the scientifically-based macro invertebrate index that measured insects and wildlife living in it.
“Can water flowing in a stream support abundant, rich, diverse ecological communities in our streams?
“The short answer, and I can unequivocally say it with scientific evidence, is a resounding yes.”
Bedford said the surveys were done since 1994 and showed improving ecological health in 87% of the 53 sites where changes could be determined.
Improving sites outnumbered those in decline by 6.6 to one while statistically significant improvements were evident at 30 sites, the highest ever and double the number of eight years ago.
Bedford said most improvement was in the intensively farmed middle to lower catchments of the Taranaki ring plain.
The upper catchment hadn’t shown any change, which was expected because it bordered a national park and wasn’t affected by land use.
“We are increasingly seeing improvements, reaching down to the coast, in more and more streams.”
Recent reports by the OECD and MFE, which concluded rivers and lakes were under pressure, were a national snapshot that didn’t reflect regional differentiation.
“You lose a sense of what is happening at region, sub-region or catchment scale,” Bedford said.
Water quality in Southland was a mixed bag, Environment Southland science and information director Graham Sevicke-Jones said.
But data for 2012 to 2016 showed a general improvement.
“The trends show that a number of areas have shown greater improvement than we have had before.”
However, while the improvement could be because of a number of factors, including the way data was collected or a climatic aberration, Sevicke-Jones said the reduction in the number of dairy conversions and the Clean Stream Accord could have contributed.
All waterways were generally suitable for wading, fishing and boating, but six of the 55 river monitoring sites didn’t meet national E. coli standards, and while nitrogen levels had increased at a quarter of monitored sites in the past 17 years there had been a decrease at three with the rest indeterminate.
Trends for total phosphorous readings and clarity were improving.
Improving water quality was much more complex than simply “pulling one lever”, Sevicke-Jones said.
Nitrogen and phosphorous were two of more than 40 factors affecting aquatic biomass.
“Everything is connected to everything else,” he said.
The quality of the Waikato River, assessed from 106 records for 11 variables from 1993 to 2012, was found to be stable in 43% of cases.
Of the balance, about half showed “important improvements” and half “important deteriorations”.
From 1991 to 2015, 23% of water quality records for the river showed improvement for phosphorous, chlorophyll and algae.
At 14% of sites there was some deterioration in turbidity and total nitrogen while temperatures and dissolved oxygen were stable.
For the rivers on the Hauraki Plains, 25 years of records at 19 sites showed mixed results.
The Kauaeranga and Ohinemuri rivers “generally had good water quality” with the Kauaeranga considered excellent, apart from moderate concentrations of E. coli.
The Piako and Waitoa rivers were of poorer quality, and the Waihou and Waitakaruru rivers had intermediate water quality with high levels of nitrogen, phosphorous and E. coli.
Most sites easily met recently released national requirements, but 25% of records showed an improvement and 11% deterioration.
Horizons monitored 36 sites throughout the Manawatu-Wanganui region and said data from 10 years to December 2015 showed improving trends for E. coli at 22% of sites, oxidised nitrogen at 55%, dissolved reactive phosphorous at 31%, and turbidity at 24%.
“Trends from January 2006 to December 2015 show efforts being made throughout the region by many landowners, organisations, iwi and councils are making a marked improvement in water quality throughout the region,” an Horizons statement said.
