Upper Lachlan
Indicator: Drinking Water Quality
Results for this indicator are also available for [an error occurred while processing this directive]
What the results tell us for the Upper-Lachlan
The microbiological quality of the supplies to the Upper Lachlan townships improved from autumn 2007 to the present, with no samples showing E.coli in the drinking water supply over this period. Prior to that time all the supplies showed the organisms intermittently in summer.
The only inorganic component of the supplies requiring attention is the high concentration of iodine in the bore water supplied to Dalton. The Guideline Value of 0.1mg/L was exceeded by the mean concentration of 0.18 over the last 4 years, with a maximum recorded of 0.34 mg/L. This is of health concern.
Quality of the water supplied
Crookwell
Crookwell drinking water supply is sourced from the Back Creek Reservoir and provides drinking water for a population of 2,100. The supply is fully treated and disinfected with chlorine.
A total of 170 samples were assessed for E. coli, and three samples showed organisms. On 28th March 2006, 74 organisms per 100 mL water were detected. On 29th November 2005 and 6th November 2006, two and one organisms respectively were detected. No organisms were reported in 2007 and 2008. This indicates a currently high quality water supply.
Seven samples were assessed for 31 different inorganic components. Two samples exceeded the pH range recommended by the National Health and Medical Research Council (NH&MRC), of pH 6.5-8.5. The mean pH was 8.4, and the highest sample was 9.0. This indicates a supply of higher alkalinity than most, but is not of health concern.
No other inorganic components were above the Guideline Values.
Dalton
Dalton drinking water supply is sourced from the Dalton Bore and provides drinking water for 130 people. The supply is disinfected with chlorine but not otherwise treated.
A total of 130 samples were assessed for E. coli, and three samples showed organisms. On 15th February 2005, two organisms per 100 mL water were detected. On 28th March 2006, 15 organisms and on 10th April 2006, nine organisms per 100mL were detected. No organisms were reported in 2007 and 2008. This indicates a water supply of currently high bacteriological quality.
Seven samples were assessed for 31 different inorganic components. Hardness and total dissolved solids uniformly exceeded the NH&MRC Guideline Values. These Values were based on lime scaling of hot water systems, and do not reflect health concerns. Chloride concentration was similarly higher than the Guidelines, but again does not have health implications.
Six of the seven tested samples in this reporting period had iodine concentrations above the Guideline Value of 0.1 mg/L. The mean concentration in the seven samples was 0.18, and the maximum 0.34. The highest iodine concentrations were in 2005; however 0.16 mg/L was recorded in June 2008, so it can be assumed that the source still provides water with a high iodine concentration. Inspection of the 2004 data showed 2 samples analysed for iodine, with a mean of 0.37 mg/L. Similar values were seen in 2002 and 2003. Thus over 7 years and analysis of 12 samples of Dalton water for iodine, 10 exceeded the NH&MRC Guideline Values, with an overall mean of 0.22 and a peak of 0.37 mg/L.
The NH&MRC Guideline Value was determined on the basis of a maximum tolerable daily intake of 1.0 mg of iodine/day, with an average drinking water consumption of 2L/day and with 80% of the iodine intake arising from food.
Thus on a hot day, with 0.37 mg/L of iodine in the drinking water, it would have been possible for members of the population to exceed the tolerable daily intake from drinking water alone.
This level of iodine intake in drinking water is of health concern.
Two samples exceeded the pH range recommended by the NH&MRC, of pH 6.5-8.5. The mean pH was 8.4, and the highest sample was 9.0. This indicates a supply of higher alkalinity than most, but is not of health concern.
No other inorganic components were above the Guideline Values.
Gunning
This drinking water supply is drawn from the Lachlan River, and provides water for a population of 560. It is chlorinated for disinfection, but not otherwise treated.
One hundred and seventy five samples were taken for bacteriological examination, and 7 showed E. coli present. The summer of 2006 was the period of highest faecal contamination, with 4 samples showing organisms, the highest being 150 per 100mL drinking water. Three samples in autumn/winter 2006 contained one organism per 100 mL, and one on 8th January 2007 contained 10 E.coli per 100 mL. No organisms were found during 2008. Summer appears to be the period most likely to find E.coli in the drinking water, and closer monitoring of the free chlorine in the supply over summer is indicated, especially as the highest E. coli count coincided with a very high Total Coliform count, presumable showing a high microbial load on the system.
Seven samples were assessed for inorganic components; minor elevations of turbidity, aluminium, and iron were reported, which had no health implications. The overall hardness of the water was high, but does not present any health consequences.
Taralga
Drinking water for Taralga is drawn from Woolshed Creek, and supplies a population of 300 people. The water supply is disinfected by Ultra Violet(UV) light, but not otherwise treated.
One hundred and six samples were assessed for E. coli, and seven samples showed the presence of the organisms, with a maximum of 95 per 100mL on 28th March 2006. This sample also had a very high number of Total Coliforms. Four of the samples containing E. coli were in 2005, with a peak of five organisms per 100 mL in October. Two samples in February 2007 had one and three organisms per 100 mL, and no samples contaminated with E. coli were reported in 2008. UV sterilization requires ongoing maintenance of the light source, which appears to have been uniformly effective for the last 20 months.
Inorganic components were assessed in 8 samples, and 5 exceeded the NH&MRC Guideline Values for pH. The highest pH was 8.9 and the mean 8.6. This is only just above the Guideline range of 6.5-8.5, and has no health significance. One sample had raised turbidity.
About the data
Drinking water quality is monitored as part of the NSW drinking water monitoring programme, and detailed results can be accessed through the website http://www3.health.nsw.gov.au/waterqual/samples/register.cfm.
This report on drinking water quality for 2004-2008 is prepared from examination of this data, to illustrate the quality aspects of the water supplied for domestic consumption in the Shire. The Shire uses both public and private water supplies, but only those supplies recorded on the health database are available for comment in this report.
Interpreting the data
In 2004 the National Health and Medical Research Council introduced the Australian Drinking Water Guidelines, which provide the basis for quality assessment. These Guidelines have not included Total Coliforms as a measure of water quality for health purposes, as the organisms are widely present in soil and untreated water and grow in water pipes, and do not reflect the content of pathogenic organisms. Monitoring for Escherichia coli is, by contrast, particularly informative, since this organism occurs in large numbers in faeces and hence is an effective indicator of faecal contamination. It is killed by standard drinking water treatment and therefore should not occur in domestic supplies. The drinking water Guideline Value is zero organisms per 100ml sample and any detected organisms present in the water therefore exceed the guideline, and should result in an increase in the disinfection of the supply.
This remedial action should be taken until the E. coli count returns to zero.
While there are many other pathogens present in faecal contamination of water, monitoring of E. coli has been shown to be an effective and straightforward method for public health. Where the data from a water supply for this period show E .coli present, it has been commented upon for each water supply reported.
Concentrations of inorganic components of water supplies do not have such a sharp impact on health as faecal contamination. The Guideline Values reflect safe concentrations for lifetime exposure, and minor exceedences, which briefly occur, are of negligible risk to public health. Inorganic constituents become a risk to public health when they consistently exceed the Guideline Values, with the risk increasing with the concentration in the supply. Where these have occurred, they are commented upon in the appropriate section of the report. Unless there is accidental contamination of the supply, it is unlikely that any substantial variations in concentration of inorganic components will occur throughout any year.
Continuing concentrations that significantly exceed the Guideline Values require investigation and rectification. . The results included in this report are from 1st January 2005 to the time of writing, mid-November 2008.
The information assessed in this report is available on the NSW Health water database, and uses the current National Health and Medical Research Council Drinking Water guidelines as the reference for the analytical comparisons.
References
NSW Department of Health Drinking Water Database 2008 http://www3.health.nsw.gov.au/waterqual/samples/register.cfm.
NH&MRC and NRMMC 2004. Australian Drinking Water Guidelines. National Water Quality Management Strategy. http://www.nhmrc.gov.au/publications/synopses/eh19syn.htm
