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5. Guidelines for algae

Water Management

Recreational guidelines for toxic algae

The State Algal Advisory Committee has endorsed the National Health and Medical Research Council (NHMRC 2008) Recreational Guidelines for algae.

Research had shown that while all species of blue–green algae produce skin irritants, not all species are capable of producing liver toxins and neurotoxins. Not all toxic marine algae are known to be hazardous to recreational water users.

The interim NHMRC (2008) guidelines are different to the previous NSW guidelines which used a level of 15,000 cell/mL for recreational use of water and High, Medium and Low categories. The new interim guidelines use a Green, Amber and Red colour alert framework and are more conservative than previous guidelines.

For Freshwaters:

A Red Level Action Mode is in place when >50,000 cells of Microcystis aeruginosa are present or a biovolume of all toxin producing cyanobacteria exceeds 4 mm3/L. Red Level is also triggered if the total of all cyanobacteria (toxic and non toxic) exceeds 10 mm3/L or scums are present for long periods. At Red Mode, Local and Health Authorities should be contacted to assess risks to recreational users and appropriate measures should be taken to warn water users. Water should not be used for primary recreation.

Amber Level Alert Mode is triggered when Microcystis aeruginosa concentrations are between 5000 and 50,000 cells/mL or the biovolume of all cyanobacteria is between 0.4 and 4 mm3/L. At this alert level investigations into the causes and increased sampling of algae should be undertaken.

Green Level occurs above 500 cells/mL of Microcystis aeruginosa or >0.04 mm3/L of total cyanobacterial biovolume but below the Amber alert level. At this level routine sampling for algae should be undertaken.

For Marine and Estuarine Blooms:

• The NHMRC algae guidelines for coastal waters for recreational uses are only based on a few species due to limited knowledge on toxic algae. Red Level mode is triggered when Karenia brevis levels exceed 10 cells/mL or when Lyngbya or Pfiesteria species are in high numbers.

Further information can be found at the NHMRC website.
Guidelines for Managing Risks in Recreational Water
Australian Drinking Water Guidelines

What should I do if I suspect an algal bloom?

Blue–green algal blooms can be recognised by a green/red/brown discolouration of the water. Sometimes blue–green algae form scum on the water surface, while in other cases the colour of the water changes. The presence of blue–green algae may also cause an earthy or musty odour.

Estuarine and marine blooms can be sometimes recognised as a red colour to the water, or red scum or other colourations to the water.

If you suspect that there is an algal bloom in a water body you should contact either the local council or the management authority for the dam or water body.

Humans and animals should be prevented from drinking or swimming in the water body which is suspected of having an algal bloom.

The process for reporting algal blooms and the actions that should be taken by the various agencies is outlined in Regional Contingency Plans available from the RACC Secretariat in your area.

Who issues media releases for algal blooms?

The Regional Algal Coordinating Committees (RACCs) issue media releases for algal blooms in recreational waters. These media releases detail only Red action alert algal blooms for recreational waters brought to the attention of the Regional Algal Coordinating Committees (RACCs).

Algal blooms may also be present in other areas where no regular algal monitoring occurs. The process of issuing an algal alert is as follows:

1. Recreational sites are monitored for algae by local councils, trusts, water supply authorities and the member departments of the RACC.
2. Results of algal monitoring are sent to the Regional Algal Coordinating Committee (RACC).
3. When the level of blue–green algae in a recreational water body is greater than the recreational guideline a high alert is issued by the RACC, and a media release is sent to the media and to relevant State and Local Government representatives.

Warning signs

Algal warning signs are used to advise water users about the suitability of the water for recreation. The aim of algal warning signs is to warn the community that waters may be contaminated with algae, and that certain activities may result in ill health. The signs generally do not prohibit water based activities, but instead warn the community against undertaking water based activities at the particular location.

The agency managing the water body, or the land adjacent to the water body, is responsible for erecting, withdrawing and maintaining warning signs at recreational water bodies. The responsible agency could be the local council, the water supply authority, or a government agency, depending on the location of the site.

Signs should be erected when the level of algae is greater than the recommended guidelines. In the case of marine algal blooms signs should be erected if potentially toxic marine algae are present.

To obtain an Algal Bloom Warning Sign please contact your local Regional Algal Coordinating Committee.