Drinking water quality
What the results tell us for Snowy River
Snowy River Shire has eight water supply systems. Council took over management of one of the systems (Eucumbene Cove) during the reporting period. Council monitors the two privately operated supply systems (Cobbin Estate and Lake Crackenback Village) in the interest of public health.
The drinking water in the shire was of a high overall standard during the reporting period. The 2004 national drinking water guidelines for microbiological quality—that no Escherichia coli or thermotolerant coliforms (both indicator bacteria) be found in any water sample—were met in 96% and 95% of the samples from across the eight systems. In instances where such bacteria were encountered, an appropriate response protocol was adopted to address the problem.
The water quality requirements for chemical parameters, under the 2004 national guidelines, were met in majority of samples tested. Some exceedences occurred in pH, turbidity, aluminium, antimony, copper, iron, lead and manganese; the exceedences ranged from 1% to 24%. None of the exceedences was considered to have posed a health risk. The high natural occurrence of iron and managanese in some waters used for water supply systems in the shire warrant council monitoring their concentrations closely.
During the reporting period a microfiltration system was commissioned at the Dalgety supply system and the Adaminaby system changed its source of water; both measures were designed to help overcome problems associated with naturally high levels of iron and managanese in the water. A disinfection plant was installed at the Kalkite supply system in 2002 to address earlier instances of microbiological contamination.
It is not possible to compare directly water quality during the current reporting period with that in the previous period due to differences in the type of data used for each State of the Environment report. This report also includes three more supply systems than the 2000 State of the Environment report.
Quality of the water supply systems
Eight water supply systems provided drinking water to 5,855 people living in about 10 townships and villages within Snowy River Shire (see Table 1). Two microbiological and at least 24 chemical parameters (see Interpreting the data) were monitored in the shire's drinking water as part of NSW Health's drinking water monitoring program (NSW Health 2000). The drinking water was not monitored for pesticides as, under current protocols (NSW Health 2000), the shire was not considered to be at risk.
The majority of microbiological and chemical water quality parameters monitored from January 2001 to June 2004 met the relevant 2004 national guidelines. Those parameters that did not are shown in Table 1.
Responses to all instances of bacterial contamination relating to the eight water systems were successful, hence there was no need for the Water Utility or Public Health Unit to recommend boiling water before using for human consumption. The reported exceedences of chemical parameters in these water supply systems were not considered to be a health concern (see Interpreting the data) as most exceedences were marginal (although the number of samples was often very small).
The water quality of the Adaminaby supply system was high throughout the reporting period. Contamination by E. coli occurred in only 2% of samples tested. Subsequent water samples did not show continued presence of these bacteria as the appropriate response protocol was adopted to address the problem. No thermotolerant coliforms were reported during the reporting period.
Aluminium and iron levels exceeded guideline limits in all three samples tested, and one of the six samples tested for Antimony exceeded its guideline level (see Table 1). Turbidity level and true colour of samples did not meet guideline requirements on some occasions. None of these exceedences was considered to pose a health risk.
This supply system formerly sourced its water from the Gooruderee rivulet. Security of water supply from this rivulet has been a problem, and was highlighted during the 2003 bushfire period. This water source also had naturally elevated levels of iron and manganese. To address these problems, in May 2005 the Adaminaby supply system began sourcing its water from Lake Eucumbene; any resultant changes in water quality will be reported in the next State of the Environment report.
Cobbin Estate system
The overall quality of water from the Cobbin Estate supply system was high throughout the reporting period. The system is based on bore water, owned and operated by a group of private land owners, and its performance is monitored by council for public health reasons.
Presence of E. coli was detected on one occasion (March 2003); no E. coli data were available for 2001 and 2002. Chemical parameter exceedences were confined to one each of pH and lead (see Table 1).
The overall water quality of the Dalgety supply system was good. E. coli and thermotolerant coliforms requirements were met in 90% and 93% of samples tested, with most contaminations occurring during summer months. All instances of contamination were addressed through the appropriate response protocol so that subsequent samples were free of such bacteria. Results for thermotolerant coliforms were not available for 2003 and 2004.
Levels of iron and manganese exceeded guideline limits in all and half the very small number of samples tested, respectively (see Table 1). Turbidity and true colour each failed to meet guideline requirements on one occasion. None of these exceedences was considered to pose a health risk.
The Dalgety supply system draws water from the Snowy River, which has naturally high levels of turbidity and suspended solids that have resulted historically in the supply system recording elevated levels of iron and manganese. The results for the current reporting period continued to reflect this. In October 2004 a new micro-filtration plant was commissioned to address the problem; the plant's efficacy will be assessed in the next State of the Environment report.
Eucumbene Cove system
Council took over operation of the Eucumbene Cove supply system from Snowy Hydro in 2003. This system, which takes water from Lake Eucumbene, is an untreated water supply. Nevertheless, the overall quality of water supplied was high.
E. coli and thermotolerant coliforms were detected on only two occasions (May and August 2002) in the system (See Table 1). Subsequent water samples did not show continued presence of these bacteria as the appropriate response protocol was adopted to address the problem. No thermotolerant coliform data were available for the period before April 2002, and for 2003 and 2004.
All chemical parameters tested met guideline requirements with the exception of iron and pH. Two of the three iron results and one of five pH results did not meet guideline limits. None of these exceedences was considered to pose a health risk.
The Jindabyne supply system sources its water from Lake Jindabyne and services Jindabyne township and the area to the south, including an industrial precinct, holiday resorts and two semi-rural estates. The water supplied by this system was of a high quality throughout the reporting period.
Microbiological exceptions were restricted to one instance each of E. coli and thermotolerant coliforms contamination (both in January 2002). Appropriate action was taken and subsequent samples did not reveal the presence of such bacteria. Results for thermotolerant coliforms were not available for 2003 and 2004.
Aluminium exceedence of the guideline value occurred on one occasion, although results for aluminium were not available for 2001 and 2002. Copper concentration exceeded the guideline value on two occasions (February and March 2002). There were five exceedences of pH guideline values, and also a one-off turbidity exceedence (in February 2003). None of these exceedences was considered to pose a health risk.
Jindabyne East system
The Jindabyne East supply system draws its water from Lake Jindabyne and covers Jindabyne East, Berridale and Tyrolean Village. The overall quality of the water supplied was high. E. coli contamination occurred on eight occasions, mainly during summer months of 2001–02. The seven instances of reported thermotolerant coliform contamination also followed a similar pattern. On each occasion, appropriate action was taken to address the problem and subsequent samples did not reveal the presence of such bacteria. Results for thermotolerant coliforms were not available for 2003 and 2004.
Exceedence of chemical quality parameters was confined to pH. It occurred on two instances and was of marginal concern.
The Kalkite supply system sources its water from Lake Jindabyne. The overall quality of the water supplied was high. Contamination by E. coli and thermotolerant coliforms occurred on nine and seven instances, respectively, during the reporting period. The majority of these contaminations took place during the first half of 2002. The problem was addressed by adopting the appropriate response protocol, and subsequent samples did not reveal the presence of such bacteria. The supply system used to be run without disinfection but in 2002 a chlorine dioxide gas disinfection plant was put in place.
All chemical parameters tested met guideline requirements, excepting an isolated instance each of pH and turbidity. These were not considered to have posed a health risk.
Lake Crackenback Village system
Water provided by the Lake Crackenback Village supply system was of a high quality throughout the reporting period. All samples from the system met all chemical and microbiological parameters for which they were tested. This system is owned and operated by Lake Crackenback Resort, and council monitors its performance in the interest of public health.
About the data
Water samples were collected by Snowy River Shire Council and sent to relevant NSW Health laboratories for chemical and microbiological analyses, based on a schedule outlined in NSW Health (2000). Details of the monitoring program, including allocation of sample numbers based on the type of water supply system and population, and details of the response protocol when national standards are exceeded, can also be found in NSW Health (2000).
NSW Health provided analytical service through its Division of Analytical Laboratories in Sydney (microbiology and chemistry) and the Greater Murray Public Health Laboratory in Wagga Wagga (microbiology only). The results are owned by Snowy River Shire Council but maintained on the NSW Drinking Water Database (a statewide internet-based database) by NSW Health's Water Unit.
The data used for this report were sourced from the NSW Drinking Water Database. Results used only cover the period 1 January 2001 to 30 June 2004, as the database does not hold earlier data for any local government area. Further details of the database can be obtained from the NSW Health Water Unit.
Interpreting the data
The Australian Drinking Water Guidelines 2004 (NHMRC and NRMMC 2004)—here called the 2004 national guidelines—provide the standards for drinking water quality nationally. Although the 2004 national guidelines have superseded the 1996 national guidelines, they are yet to be ratified by the NSW Government. Consequently, the 1996 national guidelines are still being used in the NSW Drinking Water Database for determining exceedences. However, for this State of the Environment report, the 2004 national guidelines were adopted as the standards for analyses and interpretation of data to assess drinking water quality in the shire during the current reporting period.
E. coli and other thermotolerant coliforms are used as specific indicators of faecal contamination and hence the safety of water for drinking. When these organisms are detected in water samples, the water utility responds by raising the level of treatment with chlorine or other acceptable disinfectants to destroy potentially pathogenic coliforms.
The NSW Drinking Water Database contains instances of samples not meeting guideline requirements for total coliforms. This is because the database still uses the 1996 national guidelines which set a guideline value of 0 CFU/100 mL for total coliforms. However, since the 2004 national guidelines does not adopt a guideline value for coliforms (excluding E. coli) due to the lack of direct health significance, such exceptions in the data have been ignored for purposes of this report.
Most of the reported exceedences of chemical parameters in the shire were not considered to be of health concern as they were only marginally outside the 2004 national guideline values and/or the values are not health based:
- aluminium (reported value of 0.29 mg/L compared with guideline value of 0.2 mg/L; the reported value was within the 0.01–0.9 mg/L range for major Australian reticulated supplies; guideline not health based)
- antimony (reported values of less than 0.005 mg/L were very close to guideline value and detection limit for this contaminant)
- copper (the three reported values ranged from 2.3 mg/L to 2.7 mg/L, compared with guideline limit of 2 mg/L)
- lead (reported value of 0.015 mg/L compared with guideline limit of 0.01 mg/L)
- manganese (reported values ranged from 0.7 mg/L to 3.6 mg/L compared with guideline limit of 0.5 mg/L)
- pH (the three reported values ranged from 8.6 to 9.2 compared with guideline range of 6.5–8.5; all exceedence values were well within the range of 6–10.8 reported for major Australian reticulated water supplies)
- true colour (the two reported values of 15.8 HU and 24.8 HU are within the 1–25 HU range reported for major Australian reticulated supplies for filtered or fully treated supplies).
Two of the nine iron exceedences in the shire were greater than 3 mg/L. Iron concentration above 3 mg/L can become a health hazard, although 3 mg/L is well in excess of the concentration that would cause the water to taste objectionable, and it is unlikely that such water would be consumed (NHMRC and NRMMC 2004).
NHMRC and NRMMC (2004) Australian Drinking Water Guidelines 2004, National Water Quality Management Strategy, National Health and Medical Research Council and the Natural Resource Management Ministerial Council.
NSW Health (2000) Drinking Water Monitoring Program, October 2000, NSW Health Department, viewed 30 April 2005, http://www.health.nsw.gov.au/public-health/ehb/water/monitoring/DWMonitProgOct00.pdf.
|Water quality parameter3||January–June 2001||2001–02||2002–03||2003–04||January 2001–June 2004|
|No. of samples||No. of failures||Success rate (%)||No. of samples||No. of failures||Success rate (%)||No. of samples||No. of failures||Success rate (%)||No. of samples||No. of failures||Success rate (%)||Total no. of samples||Total no. of failures||Overall success rate (%)|
|Adaminaby Water Supply System (supplies Adaminaby; supply population 400)|
|Cobbin Estate Water Supply System (supplies Cobbin Estate; supply population 50)|
|Dalgety Water Supply System (supplies Dalgety; supply population 100)|
|Eucumbene Cove Water Supply System (supplies Eucumbene Cove; supply population 10)|
|Jindabyne Water Supply System (supplies Jindabyne; supply population 2,800)|
|Jindabyne East Water Supply System (supplies Jindabyne East, Berridale and Tyrolean Village; supply population 2,095)|
|Kalkite Water Supply System (supplies Kalkite; supply population 150)|
|Lake Crackenback Village Water Supply System (supplies Lake Crackenback Village; supply population 250)|
|All water samples tested during the reporting period met 2004 national guidelines requirements|
1 For an explanation of the 2004 national guidelines, see Interpreting the data; 2 No results available prior to 1 January 2001; 3 Does not include total coliforms