2003-22: Kings Canyon (Northern Territory). Radioactivity, Selenium, Lead, Hardness, Total Dissolved Solids, Iodine, Chloride

Kings Canyon (Northern Territory) Radioactivity

2003/4: Radionuclides or radiation emitting elements are sometimes found in drinking water supplies. In the Northern Territory these elements are natural to the environment and are characteristic of the local hydrogeology. Within the new Australian Drinking Water Guidelines, the measurement of these parameters is not based on concentration as with other parameters, but in terms of risk associated with annual dose per year. A dose above the guideline trigger value of 0.5 mSv/Yr requires ongoing monitoring and operational solutions to be investigated. In the coming year, Power and Water will be investigating options to reduce the total annual radiological dose to below the trigger value in Kings Canyon.

2007/8: Kings Canyon water supply has radioactivity levels higher than other Northern Territory water supplies. In July 2007, Queensland Health Scientific Services completed a report on the radiological properties of the water used for domestic and industrial purposes and subsequent wastewater treatment.

This study determined the combined total average dose per annum to be 0.69 mSv/yr. Although this value exceeds the guideline level for intervention (0.5 mSv/yr) the total annual dose guideline value (1.0 mSv/yr) has not been exceeded.

In response, the supply was sampled monthly during 2007-08. The annual radiological dose can be estimated from the average of the potential maximums calculated for each monitoring point within the supply. Using this approach, the potential maximum annual radiological dosage (95th percentile) is 0.88 mSv/yr. Power and Water will improve aeration at Kings Canyon and investigate advanced treatment systems to further reduce radionuclide levels.

2009/10: Kings Canyon water supply has higher levels of radionuclides than other Northern Territory water supplies and is intensely monitored. Despite the large amount of radiological data available for this water supply, all radionuclides contributing to the radioactivity of this supply were not identifi ed. The total annual radiation dose for the Kings Canyon water supply is reported as the worst case estimate.

2015/16: The Kings Canyon’s water supply has higher levels of radionuclides than other Northern Territory water supplies and as a result is intensely monitored. For example, 241 samples were collected from the Kings Canyon supply between 2014 and 2016. Fourteen of these samples exceeded the 1.0 mSv/year limit with the highest value, 2.08 mSv/year, recorded at the ground level tank outlet (same sample location for all the recorded highest levels). Kings Canyon’s ARD for 2015-16 is 1.07 mSv/year (95th percentile).

Highest Levels Kings Canyon

2003/04: Kings Canyon Radiological 0.7mSv/yr

2005/6: Kings Canyon Radiological 0.48mSv/year

2009/10: Kings Canyon Radiological 2.37mSv/yr

2011/12: Kings Canyon Radiological 1.04mSv/yr

2012/13: Kings Canyon Radiological 1mSv/yr

2013/14: Kings Canyon Radiological 0.95mSv/yr

2014/15: Kings Canyon Radiological 1.05mSv/yr

2015/16: Kings Canyon Radiological 1.07mSv/yr

2016/17: Kings Canyon Radiological 1mSv/yr
2017/18: Kings Canyon Radiological 1mSv/yr (95th %)
2020/21: Kings Canyon Radiological 1mSv/yr (95th %)
2021/22: Kings Canyon Radiological 0.9mSv/yr (av.)

Kings Canyon – Northern Territory – Selenium

2003/04: Kings Canyon Selenium 0.015mg/L

2005/6: Kings Canyon (Northern Territory) – Selenium 0.011mg/L

2007/08: Kings Canyon Selenium 0.01mg/L

2008/9: Kings Canyon (Northern Territory) – Selenium 0.01mg/L (95th %)

2009/10: Kings Canyon (Northern Territory) – Selenium 0.01mg/L (95th %)


“Based on health considerations, the concentration of selenium in drinking water should not
exceed 0.01 mg/L.

Selenium and selenium salts are widespread in the environment. Selenium is released from natural and human-made sources, with the main source being the burning of coal. Selenium is also a by-product of the processing of sulfide ores, chiefly in the copper refining industry.

The major use of selenium is in the manufacture of electronic components. It is used in several other industries, and selenium compounds are used in some insecticides, in hair shampoos as an anti-dandruff agent, and as a nutritional feed additive for poultry and livestock.

Selenium concentrations in source waters are generally very low and depend on local geochemistry, pH and the presence of iron salts. Concentrations in drinking water supplies overseas are generally below 0.01 mg/L but groundwater concentrations as high as 6 mg/L have been reported in the United States.”

Australian Drinking Water Guidelines 2011

Kings Canyon (Northern Territory) Lead

2006/11: Kings Canyon Lead 0.011mg/L (av.)

Lead Australian Drinking Water Guideline 0.01mg/L

“… Lead can be present in drinking water as a result of dissolution from natural sources, or from household plumbing systems containing lead. These may include lead in pipes, or in solder used to seal joints. The amount of lead dissolved will depend on a number of factors including pH, water hardness and the standing time of the water.

Lead is the most common of the heavy metals and is mined widely throughout the world. It is used in the production of lead acid batteries, solder, alloys, cable sheathing, paint pigments, rust inhibitors, ammunition, glazes and plastic stabilisers. The organo-lead compounds tetramethyl and tetraethyl lead are used extensively as anti-knock and lubricating compounds in gasoline…ADWG 2011

Kings Canyon – Northern Territory – Hardness

2003/04: Kings Canyon Hardness 300mg/L

2004/05: Kings Canyon Hardness 304mg/L

2005/06: Kings Canyon Hardness 312mg/L

2006/07: Kings Canyon Hardness 332mg/L

2007/08: Kings Canyon Hardness 348mg/L

2008/09: Kings Canyon Hardness 360mg/L

2009/10: Kings Canyon Hardness 363mg/L

2010/11: Kings Canyon Hardness 365mg/L

2011/12: Kings Canyon Hardness 371mg/L

2012/13: Kings Canyon Hardness 374mg/L

2013/14: Kings Canyon Hardness 370mg/L

2014/15: Kings Canyon Hardness 359mg/L

2015/16: Kings Canyon Hardness 381mg/L

2016/17: Kings Canyon Hardness 377mg/L


“To minimise undesirable build‑up of scale in hot water systems, total hardness (as calcium
carbonate) in drinking water should not exceed 200 mg/L.

Hard water requires more soap than soft water to obtain a lather. It can also cause scale to form on hot water pipes and fittings. Hardness is caused primarily by the presence of calcium and magnesium ions, although other cations such as strontium, iron, manganese and barium can also contribute.”

Australian Drinking Water Guidelines 2011

Kings Canyon – Northern Territory – Total Dissolved Solids

2005/06: Kings Canyon Total Dissolved Solids 803 mg/L

2008/9: Kings Canyon Total Dissolved Solids 821 mg/L

2005/06: Kings Canyon Total Dissolved Solids 803 mg/L

2011/12: Kings Canyon Total Dissolved Solids 816mg/L

2012/13: Kings Canyon Total Dissolved Solids 825mg/L

2016/17: Kings Canyon Total Dissolved Solids 815mg/L


“No specific health guideline value is provided for total dissolved solids (TDS), as there are no
health effects directly attributable to TDS. However for good palatability total dissolved solids
in drinking water should not exceed 600 mg/L.

Total dissolved solids (TDS) consist of inorganic salts and small amounts of organic matter that are dissolved in water. Clay particles, colloidal iron and manganese oxides and silica, fine enough to pass through a 0.45 micron filter membrane can also contribute to total dissolved solids.

Total dissolved solids comprise: sodium, potassium, calcium, magnesium, chloride, sulfate, bicarbonate, carbonate, silica, organic matter, fluoride, iron, manganese, nitrate, nitrite and phosphates…” Australian Drinking Water Guidelines 2011

Kings Canyon – (Northern Territory) – Iodide

2006/07: Kings Canyon Iodide 0.395mg/L

2007/08: Kings Canyon Iodide 0.4mg/L

2008/09: Kings Canyon Iodide 0.41mg/L

2009/10: Kings Canyon Iodide 0.41mg/L

2010/11: Kings Canyon Iodide 0.43mg/L

2011/12: Kings Canyon Iodide 0.43mg/L

Up to 2011, Iodide had a health guideline of 0.1mg/L. This was increased to 0.5mg/L in 2011. Kings Canyon therefore was exceeding the health guideline for Iodide for much of the 2000’s, than was under the new guideline starting in 2011.

Kings Canyon (Northern Territory) – Chloride

2010/11: Kings Canyon Chloride 261mg/L

2011/12: Kings Canyon Chloride 265mg/L

2012/13: Kings Canyon Chloride 253mg/L

2015/16: Kings Canyon Chloride 263mg/L

2016/17: Kings Canyon Chloride 261mg/L

“Chloride is present in natural waters from the dissolution of salt deposits, and contamination from effluent disposal. Sodium chloride is widely used in the production of industrial chemicals such as caustic soda, chlorine, and sodium chlorite and hypochlorite. Potassium chloride is used in the production of fertilisers.

The taste threshold of chloride in water is dependent on the associated cation but is in the range 200–300 mg/L. The chloride content of water can affect corrosion of pipes and fittings. It can also affect the solubility of metal ions.

In surface water, the concentration of chloride is usually less than 100 mg/L and frequently below 10 mg/L. Groundwater can have higher concentrations, particularly if there is salt water intrusion.

Based on aesthetic considerations, the chloride concentration in drinking water should not exceed 250 mg/L.

No health-based guideline value is proposed for chloride.” 2011 Australian Drinking Water Guidelines