Heavy metals in the Upper Macleay River
October 2015 update

Heavy metals in the Upper Macleay River

Heavy metal contamination of river systems can occur from a variety of sources including the erosion of naturally mineralised rocks, mining activities and from urban and industrial wastes and effluents. The Upper Macleay River is scattered with known naturally occurring deposits of mineral resources that have been historically mined. Contamination of the stream sediments has been well documented, due to past (1870’s to 1950’s) mine waste disposal practices. These metals can be trapped in fine sediments that are mobilised during periods of high rainfall and flooding.

Council has undertaken a number of programs to monitor heavy metals in the Macleay River, at Bellbrook, for water supply purposes. Drinking water is pumped from the shingle bed on the edge of the river. In 2005 to 2007, intensive metals analysis were undertaken following elevated levels of arsenic found in the drinking water at Bellbrook. The monitoring of the river and bore water indicated that the arsenic levels were associated with the groundwater and not the river surface water. 

In 2010, a water treatment plant was constructed at Bellbrook that had the capacity to remove arsenic from the ground water. Council’s water treatment plant at Bellbrook ensures that the water is processed in accordance with the Australian Drinking Water Guidelines (ADWG), including maintaining arsenic and antimony levels at below the guideline levels.

Council has continued to monitor the surface water quality for heavy metals. Sampling has been associated with events such as flooding and overflows of the stormwater detention ponds from the disused Hillgrove mine site. Water sampling results of the river indicated that the levels of arsenic were well below the ANZEC guidelines for recreational and agricultural uses (0.05 mg/L). No guideline levels are provided for antimony. It should be noted that the levels for antimony only marginally exceeded the ADWG guideline limits and arsenic was detected at below the ADWG for all results.

The Macleay river catchment has been the subject of a number of university research projects undertaken by the University of New England (UNE) and supported by Council. Council is continuing to support further research by the UNE on heavy metals in the Macleay River to address community concerns.

In cooperation with the Save our Macleay River committee, council has gained approval from NSW Health, to establish a monitoring project for heavy metals in the river at Bellbrook. Council is in the process of setting up this monitoring project, which will be fully funded by NSW Health. The program of monitoring will be undertaken for a period of 12 months, and it is expected that monitoring will commence in September 2013. Results for this program will be updated onto the website as results become available. A summary of the historical water quality testing for arsenic and antinomy is provided below and the full set of data is attached.

Summary of data Antimony (mg/L) Total arsenic (mg/L)
Average 0.001 0.003
Minimum 0.001 0.0025
Maximum 0.0013 0.003
ANZEC guidelines for recreation and agricultural use Not determined 0.05
Australian Drinking Water Guidelines 0.003 0.01

ANZEC guidelines: The ANZEC guidelines provide some water quality level guidelines for safe recreational and agricultural use of natural river systems, including cattle drinking, irrigation and aquaculture.

Australian Drinking Water Guidelines: These guidelines provide a framework for good management of water supplies and the provision of water that is safe to drink. These guidelines have been developed utilising the best available scientific information and are intended to be applied to treated drinking water.

Date sampled Antimony (mg/L) Arsenic (mg/L)
 4/04/2004 - <0.005
 6/06/2005 - 0.003
 6/06/2005 - 0.003
13/06/2005 - 0.002
13/06/2005 - 0.002
20/06/2005 - 0.001
20/06/2005 - 0.001
27/06/2005 - 0.002
27/06/2005 - 0.002
 4/07/2005 - <0.001
 4/07/2005 - <0.001
 1/08/2005 - 0.001
 2/08/2005 - 0.001
 8/08/2005 - 0.002
 8/08/2005 - 0.002
15/08/2005 - 0.002
15/08/2005 - 0.002
22/08/2005 - 0.002
22/08/2005 - 0.002
29/08/2005 - 0.001
29/08/2005 - 0.001
 7/09/2005 - 0.001
12/09/2005 - 0.003
12/09/2005 - 0.003
 1/11/2005 - 0.001
 1/11/2005 0.001 0.001
14/11/2005 - 0.007
14/11/2005 0.007 0.005
28/11/2005 - 0.003
28/11/2005 0.002 0.003
29/08/2006 - 0.001
30/08/2011 0.005 0.003
 5/09/2006 - 0.001
 1/09/2011 0.004 0.002
 5/09/2011 0.004 0.002
 9/09/2011 0.003 0.001
12/09/2011 0.005 0.002
15/09/2011 0.004 0.002
11/10/2011 0.005 0.002
18/10/2011 0.002 0.002
25/10/2011 0.004 0.002
 1/11/2011 0.002 0.002
 8/11/2011 0.003 0.002
22/11/2011 0.003 0.003
 6/12/2011 0.006 0.003
 6/02/2012 0.002 0.003
19/11/2013 0.0013 0.0025
10/12/2013 0.001 0.003
25/02/2014 0.001 0.004
6/01/2015 0.001 0.004
3/02/2015 0.006 0.003
3/03/2015 0.001 0.002
31/03/2015 0.001 0.002
28/04/2015 0.001 0.002
26/05/2015 0.001 0.001
7/07/2015 0.002 0.001
25/08/2015 0.002 0.001
30/10/2015 0.001 0.002

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References

  1. P. M. Ashley, B. P. Graham, M. K. Tighe, B. J. Wolfenden. Antimony and arsenic dispersion in the Macleay River catchment, New South Wales: a study of the environmental geochemical consequences. Australian Journal of Earth Scientists, 2007, 54, 83-103
  2. M Tighe, P Ashley, P Lockwood, S Wilson. Soil, water, and pasture enrichment of antimony and arsenic within a coastal floodplain system. Science of The Total Environment, 2005, Volume 347, Pages 175-186
  3. K. Telford, W. Maher, F. Krikowa, S. Foster, M. J. Ellwood, P. M. Ashley, P. V. Lockwood, S. C. Wilson. Bioaccumulation of antimony and arsenic in a highly contaminated stream adjacent to the Hillgrove Mine, NSW, Australia. Environ. Chem. 2009, 6, 133-143
  4. S. C. Wilson, P. V. Lockwood, P. M. Ashley, M Tighe. The chemistry and behaviour of antimony in the soil environment with comparisons to arsenic: A critical review. Environmental Pollution, 2010, 158, 1169-1181