Publication (Media): Bacteria Bloom in Lake Burley Griffin probably not caused by sewage

Publication Type:	Media Release
Publication Name:	Bacteria Bloom in Lake Burley Griffin probably not caused by sewage

Reference Information

Lawrence, Ian (2001) Bacteria Bloom in Lake Burley Griffin probably not caused by sewage - May 04 2001, CRCFE, Canberra - Media Release.

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Bacteria Bloom in Lake Burley Griffin probably not caused by sewage

The National Capital Authority (NCA) today released a review undertaken of the high faecal coliform levels monitored in Lake Burley Griffin over the March/April 2001 period. Faecal coliforms are a type of bacteria that may indicate possible human faecal pollution. The review was undertaken by the University of Canberra’s Cooperative Research Centre for Freshwater Ecology, Australia’s leading centre for research into the health and management of rivers and wetlands.

The review concluded that the most probable source of the faecal coliform was ‘in-lake regrowth’ of Escherichia coli (a species of coliform bacteria), associated with the decomposition of plants in the lake (algae & large aquatic plants). The plants were dying because of the rapid cooling of lake water in late March. As an ‘environmental source of faecal coliform’, the high levels were not indicative of faecal pollution of the lake or of an associated health risk.

The review also concluded that the NCA’s management of the situation, in consultation with ACT Health and Environment ACT, was in accordance with established procedures and ACT and National Water Quality Guidelines, and that the Authority had little choice but to close the lake to recreational water use.

The National Capital Authority brief also required an assessment of ongoing elevated faecal coliform levels (40 – 1000 faecal coliform cfu/100 mL*) associated with beach areas. The review concluded that ‘in-lake regrowth’, together with ‘beach sand and sediment re-growth’ of E.coli were the most probable source of these elevated numbers. *cfu: colony-forming units per 100 millilitres.

An earlier report by Ecowise, in association with Monash University, had concluded that there was no evidence linking the incidences of high bacterial faecal coliform counts with actual illness within the community. Similarly, the World Health Organisation Draft 1998 Guidelines for Safe Recreational Water Environments notes the significantly higher faecal coliform levels for beaches as compared to adjacent waters, and that there is no epidemiological evidence demonstrating any infection of bathers.

Finally, the review recommends the establishment of a risk based assessment protocol across ACT stakeholders, to better guide managers in appropriate action in the future, and in their exercise of ‘duty of reasonable care’.

Full copies of the report are available by calling the NCA on 6271 2888.

Background
Monitoring of faecal coliforms was undertaken by Ecowise Environmental for the National Capital Authority, and summarised in a ‘Special Report – Lake Burley Griffin, Ecowise Environmental, April 2001’.

The monitoring indicated extreme levels of faecal coliform (maximum of 320,000 cfu/100 mL) though much of the lake on the 20th March, with fairly rapid decline over the following weeks to typical background levels (10 – 40 faecal coliform cfu/100 mL). The ACT and National Health and Medical Research Water Quality Guideline is “a median faecal coliform value of 5 samples not to exceed 150 cfu/100 mL for primary contact activities.”

Further information on the CRC for Freshwater Ecology Review: Ian Lawrence on 6201 5371 or fax 620 5038. For general information: Liz Smith at the National Capital Authority on 6271 2876.

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