Is the Waikato River a public health hazard due to arsenic contamination?
It has long been known that the Waikato River has elevated levels of arsenic from thermal water feeding into it from natural sources, as well as via discharge from geothermal power stations. There is no debate about there being elevated levels; the only question for that remains unanswered is how harmful are these levels of arsenic to human health?
Lake Maraetai: a focal point for arsenic contamination
Lake Maraetai, on the Waikato River, receives the outfall waste from the Kinleith paper mill and has done so for decades. According to research, this lake may be the most toxic portion of the Waikato River with regards to levels of arsenic in the lake bed sediment.
Our own independent testing of Lake Maraetai Water shows that the lake water has levels of arsenic that are well in excess of drinking water standards for this toxin.
The official limit for drinking water is 0.001 grams of arsenic per cubic meter of water. Levels measured by Eurofins EFS on 19 December, 2016 found 0.026 grams of arsenic per cubic meter of water from Lake Maraetai!
This elevated contamination by arsenic may be due, in part, to the historic discharge of arsenic from Kinleith and nearby timber mills, causing a buildup of this and other toxins in the lake's sediment. What may also be contributing to unusually high levels of arsenic in Lake Maraetai is the floxing effect on heavy metals by high levels of tannin and iron contained in the mill discharge. Iron and tannin bind with heavy metals, such as arsenic, making them insoluble, thus depositing the toxins in lake sediment, instead of continuing to flow downstream.
Lake Maraetai, with the village of Mangakino nestled on its shores, is now a popular holiday venue. Are children and adults at risk of arsenic contamination and developing any of the long list of health problems associated with heavy metal buildup? Are they at risk by playing in the water and stirring up the sediment, eating watercress and trout, and from using aquatic plants as compost on their vegetable gardens.