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Harmful Algal Blooms

Why cyanobacteria blooms are bad for business

Harmful algal blooms (HABs) pose a significant threat to water quality and public health, making their management a crucial concern for water service providers. These rapid growths of algae can produce toxins that contaminate drinking water, disrupt aquatic ecosystems, and pose health risks to humans and animals.

This toolkit aims to equip water service providers with the knowledge and resources necessary to understand, monitor, and mitigate the impacts of harmful algal blooms. By implementing effective strategies and practices outlined in this guide, water service providers can safeguard water quality, protect public health, and ensure the sustainable management of water resources.

WHO Guide to Cyanobacteria

The HAB Action Plan

This action plan is for Queensland drinking water service providers whose approved Drinking Water Quality Management Plan does not include HAB management.

In November 2023, Queensland Health hosted a workshop with representations from the Department of Environment, Science and Innovation, the Water Supply Regulator, the Queensland Health Forensic and Scientific Services laboratory, qldwater , Sunwater, Seqwater, Mount Isa Water Board, two universities and a consultancy. As an outcome of the workshop, Queensland Health developed the generic HAB Action Plan specifically for Queensland drinking water service providers whose approved Drinking Water Quality Management Plan does not include HAB management.

The workshop was in response to concerns around the increasing frequency in potentially harmful algal blooms (HABs), particularly for HABs impacting drinking water service providers who may have limited experience with HABs or may be experiencing HABs for the first time and are unaware of how to best manage, report and treat HABs. Existing guidance in the Australian Drinking Water Guidelines (ADWG) can be challenging to follow without additional interpretation.

Generic HAB Action Plan

Download the HAB Action Plan

Queensland Health FAQs

In November 2024, Queensland Health released a new HAB FAQ on their refreshed ‘Water contaminants and public health risks’ webpage. Questions include:

  • What is a harmful algal bloom?
  • Where and when do HABs occur?
  • What is harmful about a HAB?
  • What is cyanobacteria?
  • What species of cyanobacteria produce toxins?
  • What makes a bloom produce toxins?
  • How are people exposed to cyanobacteria and their toxins?
  • What are the health effects of exposure to cyanobacteria and their toxins?
  • Can toxins be removed by boiling the water?
  • What is the best method for sampling algae, cyanobacteria and cyanotoxins?
  • How are HABs measured?
  • Who should members of the public notify of a HAB?
  • What should a drinking water service provider do if a HAB is detected in drinking water sources or storages?
  • Are there any guidelines for exposure to toxins via drinking water?
  • What if algae or toxins are detected in treated water storages or the reticulation network?
  • What impact can HABs have on drinking water?
  • Can HABs be removed by drinking water treatment processes?
  • What options are there for preventing HABs in surface water?
  • Should recreational contact/fishing be limited during HAB events?
  • Can seafood from HAB affected waters be eaten?
  • Can water affected by HABs be used for agriculture?
  • When should the public be advised of a HAB event?
  • s water affected by HABs safe for pets?
  • What other sources of information are available?

Download the FAQs here.




Queensland Health HAB FAQs
WRF Guide for Utilities

Utility Guidance Manual for the Monitoring and Management of Cyanobacterial Blooms

Cyanobacterial blooms challenge utilities in their commitment to producing high-quality drinking water due to the potential production of secondary metabolites such as cyanotoxins or taste and odour (T&O) compounds. When producing these metabolites, cyanobacterial blooms are commonly referred to as HABs.

This manual offers guidance on early detection and source water management strategies to minimise the risk associated with cyanobacterial blooms. Information presented here is a synthesis of project findings from a survey of drinking water utilities with bench- and field-scale evaluations. The manual provides utilities with strategies that can be used to (1) create a structured early warning monitoring program using a tiered approach, (2) evaluate benthic sources of cyanobacteria, and (3) evaluate methods to prevent or control blooms in source water supplies.

The manual was produced by the Water Research Foundation and you will need to create a free account to be able to download it.

Download the publication here.

Management Strategies for Cyanobacteria (Blue-Green Algae):

A Guide for Water Utilities

The CRC for Water Quality and Treatment in partnership with SA Water, United Water International and Veolia Water developed a guide to help water utilities better manage cyanobacteria in source water and all stages of the treatment process.

The Management Strategies for Cyanobacteria (Blue-Green Algae): A Guide for Water Utilities is a comprehensive manual which consolidates current knowledge on the management of cyanobacteria (blue-green algae).

(Please note that this was published prior to name changes for some common species of cyanobacteria.)

Cover of Management Guide

The guide includes

  • An introduction to cyanobacteria including an outline of the health effects of toxins and description of the tastes and odours associated with cyanobacteria.
  • A description of the current guidelines and standards that relate to toxic cyanobacteria.
  • Management of source water including a description of the life cycle of cyanobacteria and factors affecting growth to help the water supplier understand the effect of management strategies for the control of cyanobacteria.
  • Sampling and monitoring programs and their rationale are also described.
  • An overview of the best procedure for assessing the risk of toxic algal outbreaks in a water supply and a description of the monitoring aid known as the “Alert Levels Framework‟.
  • An evaluation of nutrient control, mixing strategies and algicides.
  • Treatment strategies including advice on conventional treatment, oxidation by chlorine and ozone and adsorption by granular activated carbon (GAC) and powdered activated carbon (PAC), biological filtration, UV and membranes and multiple barrier options.
  • Recommendations regarding the most cost-effective treatment strategies for particular conditions.
  • A comprehensive summary of the treatment options available for the management of cyanobacteria and their metabolites is given in Tables 22 and 23.
  • A flow diagram that summarises the major management processes recommended when cyanobacteria are present in a water supply and identify potential tools and actions to deal with each particular management task. The flow diagram is designed so that a water manager can identify when and where a problem exists and find a management tool or action that may be appropriate for their situation.

Download the guide here.

Australian Drinking Water Guidelines

The ADWG contains guidance on cyanobacteria and their toxins, including health effects for toxins, and notification and alert levels for key species. The information in the guidelines is based on decades of experience with HABs in Australia.

Pages 355 to 376 (version 3.8, updated September 2022) contains detailed information on cyanobacteria and their toxins, including notification and alert levels for key species, and a health-based guideline value for microcystins. Please note that these guidelines were produced before changes were made to the names of key species of cyanobacteria.

Download the publication here.

Australian Drinking Water Guidelines
Cyanobacteria Lamiot

Hazen Adams Cyano TOX Version 3

The American Water Works Association published an excel file designed to help utilities understand the conditions (pH, oxidant dose, contact time) required to degrade different cyanotoxins.

Download the spreadsheet here.

Algae Labs

Where to get your testing done

Lab name Phone Email Website Address
Townsville Laboratory Services 4727 8666 labenquiries@townsville.qld.gov.au Townsville Laboratory Services 421 Angus Smith Dr, Douglas QLD 4814
Ecoscope Environmental 4926 0630 admin@ecoscope.com.au Ecoscope Environmental 79 Elphinstone Street, Berserker QLD 4701
ALS Environmental 3243 7222 ALSEnviro.Brisbane@alsglobal.com ALS Global 2 Byth Street, Stafford QLD 4053
ALS Environmental 4773 0000 ALSEnviro.Townsville@alsglobal.com ALS Global 13 Carlton Street, Kirwan QLD 4817
Symbio Laboratories 1300 703 166 Admin@symbiolabs.com.au Symbio Labs 52 Brandl Street, Eight Mile Plains QLD 4113
Queensland Health 3096 2850 Rebecca.Morgan3@health.qld.gov.au or Karen.Reardon@health.qld.gov.au Queensland Health Water Testing 39 Kessels Road, Coopers Plains QLD 4108, Australia
Biosecurity Sciences Laboratory 3708 8762 bslclo@daf.qld.gov.au Biosecurity Services Health and Food Sciences Precinct, 39 Kessels Road, Coopers Plains, QLD 4108
SAS 3856 7550 SASLAB@urbanutilities.com.au SAS Laboratory Services 180 Ashridge Road, Darra QLD 4076
City of Gold Coast Scientific Services Laboratory 5581 1960 scientificservices@goldcoast.qld.gov.au Gold Coast Scientific Services Smart Water Research Centre, Southport QLD 4215

Webinar Series on HABs

The warm conditions that makes Queensland so attractive to those living in colder climates unfortunately means that cyanobacteria blooms (otherwise known as Harmful Algal Blooms or HAB) appear in surface waters unusually early in the season, and in locations where they have historically been infrequent.

In 2023, qldwater hosted a series of webinars focused on three different aspects of HABs that are relevant to drinking water service providers, followed by member perspectives in Townsville and Mount Isa.

Recordings of the webinars are available below:

Webinar 1: Bureau of Meteorology (BOM) climate and water outlook for the 2023-24 summer

Thursday 20 October 2023

by Matthew Coulton, General Manager Agriculture and Water at the Bureau of Meteorology

We have all seen a warmer than average winter and now, with both an El Niño and a positive Indian Ocean Dipole (IOD) underway, their combined impact can increase the chance of below average rainfall over much of Australia and higher temperatures across the southern two-thirds of the country. Based on history, it is now also more likely that warm and dry conditions will persist over eastern Australia. El Niño events also increase the risk of extreme temperature shifts like heatwaves, hotter days and increased fire risks. Matt provided a Climate and Water briefing for the 2023-24 summer.

Webinar 2: Managing HAB through your Drinking Water Quality Management Plan: Office of the Water Supply Regulator

Thursday 26 October 2023

by Ted Aldred, Manager Water Supply Regulation – Water Operations and Systems, Department of Regional Development, Manufacturing and Water

Blue green algae outbreaks in surface waters can be challenging for water service providers, especially when coupled with other risks that are heightened by high temperatures. Boiling drinking water is not an effective means for removing or inactivating toxins associated with HABs. In this webinar Ted talks about the role of the Drinking Water Quality Management Plan in managing these risks to provide safe drinking water for your community.

Download the presentation

Download Management Strategies for Cyanobacteria (blue-green algae): a guide for water utilities

Webinar 3: Health Aspects of Harmful Algal Blooms

Thursday 2 November 2023

by Dr Phil Choi, Senior Environmental Health Scientist, Queensland Public Health and Scientific Services, Queensland Health

The conditions that favour HABs include warm temperature, stratified water and calm or stagnant conditions: all circumstances that are associated with drier than usual wet seasons. If HABs do occur, they have the potential to impact drinking water supplies as well as recreational and irrigation water supplies. Queensland Health is currently updating its FAQ on HAB, and in this presentation Phil provides an overview of the different kinds of algae, the impact of location that leads to toxins forming, and how these impact on the health of people and animals.

Download the presentation

Other resources mentioned in the presentation:

American Water Works Association Resources on Cyanobacteria/Cyanotoxins

US EPA Resources on Cyanobacterial Harmful Algal Blooms in Water Bodies

Webinar 4: Service provider experiences with HAB

Thursday 9 November 2023

In this webinar we have presentations from water service providers with experience in management of harmful algal blooms reflecting on different mitigation strategies, what worked, what didn't and other lessons learned.

Tania Strixner-Harvey from Mount Isa Water Board presents on "Blue-green algae at Clear Water Lagoon: The journey so far…"

Trish Knavel and Laura Shiels from Townsville City Council presents "Managing Harmful Algal Blooms – Townsville City Council’s Experience"

Download the Townsville City Council presentation