Weekly water quality sampling for E.coli at the two river pools in Bright and Porepunkah is undertaken by Council during the warmer months.
These E.coli results are used by Council to provide the weekly update of the condition at each site. Water quality condition ratings are calculated using the results of the previous five weeks of sampling. These will be indicated once five weeks of sampling data are available.
What are the ratings?
Each site has been given a water quality condition rating, calculated using the results of weekly bacteria samples. The rating is based on a statistical average of E.coli (the geometric mean) over the last five samples. This average is compared to rating categories based on Victoria's current environmental quality objectives for primary and secondary contact recreation. To give users current information on recreational water quality, the ratings are based on samples taken under all weather conditions and are updated weekly.
The ratings are indications of recreational water quality over the previous five weeks, and do not give a measure of risk to the health of river users on any given day, or of the quality of drinking water. Drinking water is the responsibility of North East Water, and these readings are indicators of recreational water quality only. River users should take care at all times and not swallow river water. They should also be mindful of other potential hazards such as high flows, unseen objects and litter. Avoid swimming 24-48 hours after heavy rain.
The rating system has three categories:
• Good water quality - The E.coli geometric mean, based on the last five samples, has remained below the primary contact objective of 200 organisms per 100mL. These sites are generally considered suitable for all forms of recreation. Although the water quality is good, there may still be some potential health risk for some people. On occasions, such as after high rainfall, there may be an increased possibility of contamination from runoff, which may contain animal or human waste.
• Fair water quality - The E.coli geometric mean, based on the last five samples, is in the range between 201 and 1000 organisms per 100mL. Sites with water quality in this range are considered suitable for boating, but not generally suitable for swimming. River users should use their own judgement when deciding to swim, looking out for signs of stormwater or other pollution. There is a potential health risk for some people from exposure to the water, particularly if swallowed. High rainfall events may increase the risk of contamination from animal or human waste.
• Poor water quality - The E.coli geometric mean, based on the last five samples, is in the range between 1001 and greater than 5000 organisms per 100mL. Sites with water quality in this range may be used for boating, but they are not suitable for swimming. There is a greater potential health risk to river users from exposure to the water, particularly if swallowed. High rainfall events may further increase the risk of contamination from animal or human waste.