Residents of Waikouaiti and Karitane are angry and demanding answers after it was revealed this week elevated lead levels have been intermittently detected in their town's water supply - a problem first discovered almost six months ago.
So why did it take so long for the public to find out? How dangerous is the problem? And what is known about the towns?
Where are Waikouaiti and Karitane?
The two small coastal settlements both sit north of Dunedin. State Highway 1 traces through the centre of Waikouaiti about 33km north of central Dunedin. Karitane sits about 5km south of Waikouaiti off State Highway 1 along Coast Road. According to the 2018 census, 1194 people are usually resident in Waikouaiti, up from 1122 in 2013. According to the 2013 census, 360 people called Karitane home.
Both towns are within the Dunedin City Council area. The towns' tap water system is separate from the main city supply and a small treatment plant sits near the Waikouaiti River, which feeds the plant. The treatment facility was upgraded in 2009. In 2016, Dunedin City Council trumpeted "Dunedin's drinking water is now among the best in the country, after a 21-year programme to improve its quality" following upgrades to the city's supply starting in 1995.
The towns are home to a large proportion of holiday homes and would have expected a boost this weekend due to the Waitangi Day long weekend.
Who knew what and when?
So far six tests since 31 July last year have shown concerning levels of lead in the town's water supply.
- The first was taken at the Waikouaiti golf club on 31 July 2020. Its results came back on 14 August showing lead at levels of 0.0295mg per litre of water (about three times the acceptable level).
- Another taken from the golf club on 9 October 2020 returned levels of 0.0121mg/L a week later.
- A test taken from the golf club on 8 December 2020 came back 10 days later showing 0.394mg/L (almost 40 times the acceptable level), while a test taken on the same day at Karitane bowls club showed lead at levels of 0.072mg/L (more than seven times the acceptable level).
- Another test at the golf club on 7 January this year, showed 0.0178mg/L.
- A test taken at the Waikouaiti water treatment plant (from the raw water reservoir) on 20 January came back nine days later showing 0.05mg/L (five times the acceptable level).
The Dunedin City Council was not specifically testing for lead at the time but was measuring the corrosivity of the supply's water and using metals as a proxy for that.
Upon receiving the 31 July test results in mid-August, the council alerted Public Health South and its independent drinking water assessor, and decided upon ongoing testing as the appropriate course of action without informing the public or elected representatives.
The council says during the next 14 weeks, lead tested well below the acceptable limits, except for the result at the Waikouaiti Golf Club on 9 October 2020.
"This trend indicated that the result received on 13 August may have been an isolated incident at a localised point on the network," the council said.
The concerning results of the 8 December test (showing almost 40 times the acceptable level) were emailed to a council staff member on 18 December, but they were not opened until the new year as the staff member was on leave at the time and did not check their emails.
The council says: "When staff picked up the results on 7 January 2021, we notified the independent drinking water assessor. Again, the expert advice we received was that more sampling and investigation was required to determine the extent of the issue. Public Health South concluded that public notification was not yet required.
"The most recent sample to indicate high levels of lead was taken at the Waikouaiti raw water reservoir on 20 January 2021. We received this result on 29 January and again notified the independent drinking water assessor (contracted by the Ministry of Health).
"The result at the Waikouaiti raw water reservoir was the first time we had received results showing elevated lead levels at the water source.
"On 2 February 2021, we received advice from the Medical Officer of Health that all consumers on the water supply should be advised not to use tap water for drinking, cooking or preparing food until further notice. We acted on that advice immediately and put a range of measures in place to inform residents and provide safe drinking water."
It is unclear what staff were involved in making these determinations as the chief executive was only informed on Monday this week of the problem.
Elected representatives had no role in decision making.
Mayor Aaron Hawkins was only told of the issue on the morning of Tuesday this week, councillors were only informed hours before the public was on Tuesday, and members of the Waikouaiti Coast Community Board found out about an hour before the matter was made public.
The Otago Regional Council told RNZ the Dunedin City Council "first contacted us on 18 January 2021 about an increase in lead levels in one of their water samples".
Both councils are now investigating the cause of the contamination but it is no clearer at present, despite several theories being floated among the public.
The council has not yet made public the concentrations of lead found in the other 84 tests carried out since August.
How much danger does the lead contamination of the water supply pose?
Authorities are currently saying the no-drinking notice, which was issued on Tuesday (186 days after lead was first detected in the supply), is a proactive and precautionary measure until the source and extent of contamination is determined.
A total of 18 samples (nine of the raw water reservoir and nine of the treated water reservoir) have been taken from the Waikouaiti Water Treatment Plant and only one, on 20 January 2021, has shown elevated lead levels.
Toxicologists have told RNZ throughout the week that concerns about lead poisoning comes with exposure over time, but individuals can respond differently to the highly poisonous heavy metal.
"It matters how long you've been exposed to this," Ian Shaw, a professor of Toxicology at Canterbury University, told RNZ today.
"If you're exposed to 40 times the drinking water standard in just a single dose it probably wouldn't cause too much of a problem. If you're exposed to that over several weeks you might get signs and symptoms of anaemia because lead will reduce the production of haemoglobin - the oxygen carrying pigment in the blood.
"But if you're exposed to that level over a very much longer period of time, this could lead to neurological damage and this is particularly worrying in kids because their nervous system, in particular their brain, is still developing. But the only way to be certain and know what the situation is - because people absorb lead differently and different people excrete it differently - is to take a blood sample and find out how much lead is in their blood and then you can deal with each individual case."
The World Health Organization states "There is no known 'safe' blood lead concentration".
"As lead exposure increases, the range and severity of symptoms and effects also increases," it says.
To reassure locals, all Waikouaiti and Karitane residents are being invited to get blood tests done, starting from Tuesday next week.
Director-General of Health Ashley Bloomfield has endorsed this plan, and said the Ministry of Health had set up an incident management team.
The National Poisons Centre told RNZ this morning it has only received three calls about lead poisoning since the issue became public knowledge.
What happens next?
Public Health South is holding a public meeting at the East Otago Events Centre, 203 Main Road, Waikouaiti, at 7pm today, to discuss the drinking water issues.
Southern DHB Medical Officer of Health Dr Susan Jack, and medical toxicologist University of Otago and National Poisons Centre Director Dr Adam Pomerleau, will discuss:
- Health impacts of lead exposure
- What they know about the possible exposure so far
- Lead level blood testing clinics for Waikouaiti and Karitane next week
They will be available to answer people's questions and advise on the next steps.
Mayor of Dunedin Aaron Hawkins, Councillor Jim O'Malley (the chairman of the council's infrastructure services committee), and the council's infrastructure services general manager, Simon Drew, will also be at the meeting.