A new report has criticised the water quality of the Waikato River, delivering a “hammer blow” to those trying to keep it clean.
And the Waikato’s famous river lakes – including Lake Karapiro – face a murky, polluted future due to runoff and nitrogen leaching from the region’s farms.
The Waikato Regional Council yesterday released a 20-year snapshot of water quality in Waikato waterways, and it doesn’t look good.
The report, by water scientist Bill Vant for Waikato Regional Council, shows “serious declining trends” in nitrogen content and water clarity across the region, which will only worsen if trends are not reversed.
Increasing nitrogen levels had the potential to stimulate the growth of algae, damage aquatic life and contribute to toxic algal blooms.
“It has to be taken seriously.
“The thing that I’m most concerned about, and what I find disturbing, is the increasing input of nitrogen into the Waikato River’s hydro lakes. The lakes respond differently to nitrogen, compared to rivers, because the water hangs around in the lakes for a long time,” Mr Vant said.
Increasing levels of nitrogen led to more algae growth and made the lakes less attractive for recreational activities.
“Lake Taupo is blue and clean but by the time you get to Lake Karapiro the water is green and murky. Over time the uppermost hydro lakes will become more and more like Lake Karapiro and Karapiro will become murkier and greener,” Mr Vant said.
Runoff and leaching of nitrogen from pastoral farming accounted for much of the increased nitrogen levels.
“The more the lakes deteriorate the fewer options society is going to have because these sites will be extremely difficult to restore,” Mr Vant said.
The report has shocked those who act as the river’s guardians, who yesterday described the report as a “hammer blow” to iwi aspirations for a clean river.
Waikato River Authority’s iwi-appointed co-chair Tukoroirangi Morgan said the council’s report was a blow to the tribes’ aspirations for a clean river but it was not time to give up the restoration work.
Over the next 27 years the authority, a co-governance body established between the Crown and Waikato River iwi, will administer $250 million to clean up the river.
“Clearly the report is a major hammer blow to all of us. It’s not new but we’ve got to get on and do the job and do it quickly,” Mr Morgan said.
“The legacy that we want to leave for our kids and those of the unborn generation that is yet to come, in 20 years, [is] we want any of our grandchildren to go up and down any part of the river and be able to take kai and swim in it.”
Mr Vant said data from 114 monitoring sites across the Waikato River and other waterways revealed significant deterioration in nitrogen levels, turbidity and water clarity.
The issue of how to manage and preserve the country’s waterways has become a hot environmental topic, with Environment Minister Amy Adams yesterday saying the Government will legislate for independent environmental reporting on five environmental domains, including freshwater.
According to ministry data, 61 per cent of monitored sites on New Zealand rivers were unsafe for swimming.
Last year the regional council embarked on its Healthy Rivers: Plan for Change project, a $2.4m initiative to amend the Waikato Regional Plan.
The purpose is to manage adverse effects from discharges to land and water in the Waikato and Waipa catchments.
Norman Barker, chairman of the council’s land and water quality subcommittee, said the water quality report confirmed the importance of the Healthy Rivers project.
“In all our conversations with the community, water quality is their No 1 concern.
“Joe Public can take comfort from the fact a lot of effort is going into halting water quality decline and restoring it,” he said.
The report includes some positive news, with significant improvements in ammonia and chlorophyll levels in a majority of Waikato River sites.
E oli bacteria levels were also stable at most sites.
Mr Vant said the upper Waikato River compared favourably to other New Zealand rivers but there had also been gains downstream.
“In the 1950s and 60s Hamilton discharged its sewage directly into the river.
“Today stretches of the river in Hamilton are swimmable and that’s probably the most important change over the past 50 years or so.”
Mr Vant said the Waikato River ranked highly compared to rivers in other developed countries, but New Zealanders had different expectations of their waterways.
“New Zealanders have high standards and expect to be able to swim in their rivers while other countries don’t have that expectation.
“While the overseas comparisons are interesting, people will argue that we should compare our river to how we want it to be.”