3.9.1 Investigative studies and research monitoring

Summary of actions

• Establish programs to increase understanding of the water supply system.

• Use information to improve management of the water supply system.

Investigative studies and research monitoring include strategic programs designed to increase understanding of a water supply system, to identify and characterise potential hazards, and to fill gaps in knowledge. Improved understanding of the factors affecting water quality characteristics allows suppliers to anticipate periods of poor water quality and respond to them effectively.

Examples could include:

• baseline monitoring of parameters or contaminants or testing of potential new water sources to identify water quality problems;

• source water monitoring to understand the temporal and spatial variability of water quality parameters;

• developing early warning systems to improve the management of poor water quality;

• event-based monitoring to determine the magnitude of impacts (duration and maximum concentrations);

• examining mixing effects within a water storage;

• evaluating characteristics of an aquifer through pumping tests and analyses;

• studying the movement of water within reservoirs to determine short-circuiting effects;

• examining backwash return water and its effect in increasing microorganism load.

In addition, monitoring could provide input into predictive modelling of source water quality or assist in the selection of management and treatment approaches.

Careful consideration should be given to the selection of water quality characteristics to be analysed, use of statistical techniques, collection of samples (frequency and location), use of appropriate sampling and testing procedures, evaluation and management of results (see Information Sheets 2.1 to 3.5).

Tracing the cause of taste and odour problems often initiates investigations. Box 3.8 illustrates one such investigation and highlights the importance of investigative studies in assisting with evaluating risk to public health.

Box 3.8

Cyanotoxin investigation in South Australia

In April 2000, water quality problems were experienced at the Upper Paskeville Reservoir, a key water supply facility to the Yorke Peninsula in South Australia. Complaints of poor tastes and odours in the drinking water supplied to consumers were investigated. The problem was traced to the presence of high concentrations of 2-methyl isoborneol produced by the blue-green benthic cyanobacterium Phormidium, which was found in the reservoir entangled in strands of a submerged aquatic plant, water milfoil.

In view of the taste and odour complaints, Paskeville Reservoir was taken out of service. At the time, existing knowledge of Phormidium toxicity suggested that there would be no health concerns to the consumers of the Yorke Peninsula, but scientists at the Australian Water Quality Centre recommended that toxicity tests of cyanobacterial material be carried out as a precaution. The material was found to be toxic.

Following these results, the South Australian Department of Human Services issued advice that, due to the potential health risk, people should not use the mains water for drinking or cooking. Temporary supplies of bottled water were distributed to Yorke Peninsula communities by South Australia Water. Hospitals, nursing homes, caravan parks, food businesses and the like were notified individually and in some cases provided with carted water. The state primary industries department advised that the mains supply should not be used for stock water.

Subsequent testing confirmed that chlorination and boiling inactivated the toxin. On this basis the public was advised that the water could be used after boiling, and the strategy for cleaning the supply was changed from flushing to a mixture of chlorination and flushing. Chloramination, which is normally used to disinfect the supply, did not inactivate the toxin.

In addition to extending monitoring in similar storages in South Australia to determine the presence of Phormidium in benthic cyanobacterial growths, research is being undertaken to characterise the toxin further. Results so far have shown that the toxic effect is associated with cell-bound material and that the toxin is only sparingly soluble, thereby reducing its potential risk to human health.

Source: Baker et al. (2001)