Arsenic levels detected in the Waikato River have raised concerns for some councils, but the overall findings indicate these levels remain within the normal range. Recent water testing shows results from various sites between Lake Ōhakuri and Rangiriri, with arsenic concentrations fluctuated between 0.0189 mg/litre and 0.0256 mg/litre, which is slightly above the maximum acceptable value of 0.01 mg/litre set for treated water. Despite this, local authorities assert the drinking water is safe for public consumption.
The update on Wednesday revealed elevated arsenic levels at two water treatment facilities, prompting responses from Auckland's Watercare and the Hamilton City Council. Subsequently, Waipā and Waikato district councils noted similarly elevated readings. A statement issued by the councils described how the arsenic levels monitored at the affected sites had been routinely within 0.0123 mg/litre and 0.03 mg/litre based on long-term historical data.
While the recent measurements indicate slightly higher levels, Waikato Regional Council's environmental science manager Mike Scarsbrook remarked, "Drinking water remains safe to drink, with arsenic levels now also meeting Drinking Water Standards for Watercare and Waikato District Council." He also pointed out, "The current levels of arsenic do not affect recreational activities like swimming."
The small rise noted has been attributed to various factors, including potential geothermal sources from Lake Taupō and accumulation of arsenic within sediments located along the hydro lakes. These treatments have their challenges due to the presence of more complex forms of dissolved arsenic, which are harder for treatment plants to filter out. According to Scarsbrook, adjustments to the water quality parameters like temperature and dissolved oxygen may also be affecting these readings, reminiscent of similar situations seen back in 2012 and 2013, which eventually rectified themselves.
Governor and health authorities have reassured the public, with the National Public Health Service's regional clinical director, Dr. William Rainger, stating, "Drinking water with slightly elevated levels for a short period of time is unlikely to impact people’s health. You do not need to boil your drinking water. It is safe to drink." Meanwhile, New Zealand Food Safety deputy director general Vincent Arbuckle indicated, "The levels detected are not harmful to animals and there is no evidence water used for animals or food production is unsafe. If there was risk to food safety, we would take appropriate action to protect consumers."
Waipā District Council’s recent test results showed some minor reduction with two main treatment plants measuring 0.0128 and 0.0131 mg/litre, down from 0.0129 and 0.0143 earlier readings. The council also added extra measures by including the Alpha Street treatment plant to their testing routine, ensuring continual compliance with standards, as confirmed by water services manager Karl Pavlovich, who stated, "We will continue to test daily. The water remains safe for drinking, bathing, and cleaning, and there is no need for people to boil it."
Meanwhile, the Waikato District Council has reported similar encouraging figures, with current measurements showing treated water supplied from plants within the district falling below the acceptable maximum value at 0.01 mg/litre, indicating compliance with the required standards. These results show the vigilance of local authorities concerning water safety and public health.
On the other hand, the Hamilton City Council's test results showed arsenic levels remained slightly elevated but assured the community the water supply remains safe for use. Unit director Three Waters Maire Porter explained the situation, saying, "The levels are not yet within the relevant Drinking Water Standard, but our water supply remains safe for everyday use. Making changes to a complex process is not something you want to rush, but we’re making incremental changes with the aim of bringing the levels back down." Their plan includes optimizing existing arsenic removal processes and potentially implementing new technology through membrane filtration systems during the upcoming days.
Watercare also reported some positive news with tests showing compliance for three consecutive days with arsenic levels recorded significantly below the maximum acceptable value. Chief Operations Officer Mark Bourne noted, "We continue to be cautiously optimistic and are continuing our daily sampling programme for the time being." He highlighted their commitment to ensuring the treatment processes are effective, emphasizing the multi-barrier process employed to eliminate contaminants.
Overall, the situation around arsenic levels within the Waikato River demonstrates the continuous effort made by local councils and water treatment facilities to monitor and maintain water safety. They aim to assure the public of their commitment to safety and health standards, reflected through their proactive measures and consistent monitoring protocols put in place to manage such environmental challenges efficiently.
