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 activity 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 21 September 2020 (next update scheduled for 2 October 2020)

  • Microalgae activity was high at Maylands and Ashfield in the Swan River this week.
  • If you are fishing in the Riverpark, remember to protect the riverbanks by fishing from jetties or platforms and avoid trampling vegetation.
  • Help keep our rivers healthy by taking rubbish home with you.

See the map below to view this week's microalgae activity 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 25 Sep 2020