Water quality monitoring in the Swan River. Photo by K Trayler/DBCA
Water quality monitoring in the Swan River. Photo by K Trayler/DBCA

Your portal to information on the river

Water quality monitoring occurs on a weekly basis in the Swan Canning Estuary and fortnightly in its catchment.

Sampling informs understandings of:

  • hydrodynamic conditions within the waterway
  • microalgae activity 
  • estuarine and catchment water quality

Hydrodynamic conditions

Extensive water quality monitoring is conducted in the Swan River from Fremantle to West Swan, and the Canning River from Mount Pleasant to Langford. Parameters measured include salinity, oxygen content and water temperature.

Water quality profile reports are prepared weekly to convey information on the prevailing conditions within the waterway. Reports published after October 2019 are available for download at the bottom of this page. Earlier reports are available on the Parks and Wildlife Service website for the Swan River and the Canning River.

In collaboration with the University of Western Australia, data collected through the water quality monitoring program is applied to a hydrodynamic-biogeochemical model and used to forecast a ten-day synopsis of conditions which is displayed spatially across the estuary.

Microalgae Activity 

A weekly Microalgae Activity Report (MAR) is prepared to inform the public on microalgae levels, the probability of discoloration and/or scum formation, and potential warnings. This is based on data collected at 20 routine monitoring sites throughout the Swan Canning river system.

Concentrations of chlorophyll-a, a plant pigment, are used to estimate microalgal activity. This is presented by the use of low, medium and high activity categories. An alert category may be used where an algal species occurs at concentrations that may be harmful to aquatic life or human health and requires public advice.


  Low Medium High Alert
  Low levels of microalgae with no likely visible impact Possibility of discolouration and/or scum formation High probability of discolouration and/or scum formation Presence of species potentially harmful to aquatic life, OR human health requiring public advice
Chlorophyll-a (µg/L) < 4 4 - 10 > 10 N/A

This week's Microalgae Activity Report

Week starting: Monday 23 March 2020 (next update scheduled for 3 April 2020)

  • The Department of Health advice regarding a toxic algal bloom warning has been extended and includes the following areas:
    • the Swan River between Pelican Point, Nedlands to South Perth Yacht Club and upstream to Middle Swan (Reid Highway) Bridge and;
    • the Canning River from South Perth Yacht Club to Kent Street Weir. 
    • Map of affected area
  • The warning is in place due to levels of concern of the microalgae, Alexandrium and the confirmed presence of Paralytic Shellfish Toxins. 
  • Members of the public are advised not to consume wild shellfish, crabs or fish from the impacted zone of the Swan Canning Riverpark. Toxins have been detected in crabs and mussels.
  • Contact the Department of Health on 9222-2000 for further information.
  • Water discolouration (red / orange / yellow) may be seen in areas where algal activity is high and blooms are present.
  • As a general rule, the public should avoid swimming in water that is discoloured, murky or smelly.
  • Sick or dying fish should be reported to FishWATCH 1800 815 507.

Use the map below to view this week's microalgae levels. Select the map icons for more information. Trouble viewing the map below? View in a new window.

MAR alert levels

Estuarine and catchment water quality

Data collected from monitoring in the Swan Canning Estuary and its catchment is compiled into annual reports to inform management. More information on monitoring, evaluation and reporting of the estuarine condition is available on the Parks and Wildlife Service website.


Page reviewed 27 Mar 2020