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Cyanobacteria in Freshwater

Topics: Contaminants and Hazards, Biological Agents, Drinking Water, Water

Cyanobacteria, commonly known as blue-green algae, are naturally occurring microscopic organisms found in fresh, brackish, or marine water that can form cyanotoxins. These toxins are a serious public health issue as exposure can cause illness and, in worst case scenarios, can be fatal (Svirčev et al. 2017). Under certain environmental conditions, cyanobacteria multiply quickly and create blooms. Blooms can occur at any time of year, but are more common during summer or early fall (USCDC NCEH 2015), and are predicted to increase in frequency and duration due to climate change impacts (Hamilton et al. 2016). The resources listed here are intended to assist public health practitioners to:

  • Recognise and prevent cyanobacterial blooms;
  • Provide guidance regarding appropriate monitoring, management, and response to a bloom in both drinking and recreational water;
  • Provide guidance on risk communication during a bloom.

NCCEH Resources

  • Cyanobacteria in freshwater (2017)
    This fact sheet provides a brief outline of some of the key points related to cyanobacteria and the toxins they produce.

Selected External Resources

  • Control and Treatment (USEPA, 2017)
    This management tool provides information on how to reduce nutrient input to prevent blooms in both recreational and drinking water; remedial/mitigation measures when blooms are present; and suggestions for water supply managers to deal with cyanoblooms and toxins.
  • Cyanobacterial toxins in drinking water (Health Canada, 2016)
    Health Canada’s proposed guidelines provide the maximum acceptable concentration of total microcystins in drinking water (1.5 µg/L), including creating an action plan, a decision tree on cyanobacteria monitoring, steps to take if cyanotoxins are detected in drinking water (Appendix B), and risk communication information (section 3.1.2, and 3.2.1; Appendix B).
  • Information update – Health Canada proposes guidance to protect infants from algal toxins in drinking water (Health Canada, 2016)
    This short update provides risk communication advice for parents of young infants when there is a risk of cyanotoxin contamination in drinking water.
  • Decision protocols for cyanobacterial toxins in BC drinking water and recreational water (Government of British Columbia, 2015)
    This guidance document provides a simplified, shorter version of information presented in Health Canada’s proposed guidelines that can be adapted for various situations, and includes a decision tree for monitoring cyanobacteria in recreational water.
  • Health effects support document for the cyanobacterial toxin microcystins (USEPA, 2015)
    This review document provides comprehensive information on physical and chemical properties, toxin synthesis and environmental fate, occurrence and exposure in water and other media, toxicokinetics, and risk characterization for microcystins.
  • Guidelines for Canadian recreational water quality – third edition (Health Canada, 2012)
    Health Canada’s guidelines for total microcystins in recreational water (20 µg/L), including discussion of other common cyanotoxins, and risk communication advice for recreational water users.

Peer-Reviewed Articles

This list is not intended to be exhaustive. Omission of a resource does not preclude it from having value.

Last updatedJun 15, 2017