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The Department of Biodiversity, Conservation and Attractions (DBCA) has a key role in monitoring, evaluating and reporting on the environmental health and community benefit of the Swan Canning Estuary and its catchment. Environmental monitoring is focused on water quality and biological indicators including fish and seagrass.

The main objectives of the evaluation and reporting program are to develop an understanding of waterway function, track trends, measure compliance against management targets, monitor the extent and severity of low oxygen and algal blooms, report changing conditions to the community, inform catchment models, guide management decisions and incident response, and determine the effectiveness of estuary and catchment management measures.

On these pages, you will find information on:


Estuary water quality

Through its Rivers and Estuaries Science program, the Department of Biodiversity, Conservation and Attractions (DBCA) conducts weekly water quality monitoring at 40 sites throughout the Swan Canning Estuary. Data from this monitoring program is reported in a number of formats including weekly water quality profile reports, microalgae activity reports and annual estuarine data reports.

Hydrodynamic conditions

Extensive water quality sampling is conducted in the Swan River from Fremantle to West Swan, and in 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 river system. These reports are available for the Swan River and the Canning River. Reports published after October 2019 are published on the Department of Biodiversity, Conservation and Attractions website. Earlier reports are available on this website for the Swan River and the Canning River.

The data used in these plots is available to the general public through the Water Information Reporting Portal or by emailing This email address is being protected from spambots. You need JavaScript enabled to view it..

Microalgae Activity Report

DBCA officers monitor microalgae on the Swan Canning river system on Mondays and Tuesdays at 20 routine monitoring sites. Samples are processed and reported within 48 hours for preparation of the weekly Microalgae Activity Report (MAR). The report  informs the public on microalgae levels, the probability of discolouration and/or scum formation and potential warnings for sites throughout the Swan Canning Estuary.

The MAR is updated on the website on Friday and in the weather report in The West Australian newspaper the following Monday.

Officers from Parks and Wildlife Service and DWER monitor the Swan and Canning rivers on Monday and Tuesday at 20 routine monitoring sites, unless delayed by a public holiday. Samples for microalgae analysis are collected, with processing and reporting taking up to 48 hours.

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 also be used and is based on the types of algal species present and their cell concentrations rather than chlorophyll-a. The alert may be used where an algal species occurs at concentrations that may be harmful to aquatic life or human health and requires public advice.

The Microalgae Activity Report is published on the Department of Biodiversity, Conservation and Attractions website.

Annual estuary water quality reports

Data collected from 20 estuarine sites as part of the Swan Canning Water Quality Monitoring project is summarised into an annual report on the water quality for six ecological management zones (see map below). Within each report, data is presented in graphical and tabular form for 13 key water quality and biological parameters. The most recent and historic water quality reports can be downloaded below.

Reporting against estuary targets

The Swan Canning Water Quality Monitoring project supports reporting against measures of Riverpark health. Targets have been set for estuarine and catchment water quality, conditions in the oxygenation zone, and fish communities. Progress against these targets are reported every two years through the River Protection Strategy Biennial Report. This is available on the Department of Biodiversity and Conservation website

DBCA's key performance indicators of water quality for the Swan Canning Estuary and its catchment, reported in the biennial report, are:

  • chlorophyll-a concentration and dissolved oxygen saturation in surface waters of the estuary
  • total nitrogen and total phosphorus concentrations in 15 priority sub-catchments

Targets for ecological management zones

The surface waters of the estuary are divided into four ecological management zones – Upper Swan Estuary, Middle Swan Estuary, Canning Estuary and Lower Swan Canning Estuary – and annual targets have been developed for each. These are based on Australian and New Zealand Environment and Conservation Council (2000) trigger values and statistical principles, to detect the smallest change in water quality. The targets for the zones relate to chlorophyll-a concentration (a measure of algal biomass) and dissolved oxygen saturation in surface waters.

Estuary Basin

Chlorophyll-a (µgL-1) target

DO Saturation (%) target

Upper Swan

19.98

81.2

Middle Swan

8.75

75.1

Canning

11.67

49.1

Lower Swan Canning

3.55

82.1



Catchment water quality

Through its Rivers and Estuaries Science program, the Department of Biodiversity, Conservation and Attractions (DBCA) conducts fortnightly monitoring at 33 sites within 27 of the 31 sub-catchments of the Swan Canning river system. Data from this monitoring program is reported in a number of formats including annual catchment data reports and sub-catchment nutrient reports.

Catchment water quality data reports

Water quality data collected fortnightly from 33 catchment sites as part of the Swan Canning Water Quality Monitoring project is summarised into annual reports, which are available for download at the bottom of this page. 

Annual reporting against catchment targets

DBCA's key performance indicators of water quality for the catchment of the Swan Canning Estuary are:

  • total nitrogen and total phosphorus concentrations in 15 priority sub-catchments

Targets for catchments

Median total nitrogen and total phosphorus targets have been developed for catchment tributaries of the Swan Canning river system. In recognition of the long timeframes required for catchment management to affect nutrient levels in tributaries, both short term and long-term targets have been developed.  The long-term targets are based on Australian and New Zealand Environment and Conservation Council (ANZECC) (2000) trigger values for near pristine rivers while the short-term targets are double the ANZECC recommendations.

Target Total nitrogen (mgL-1) target Total phosphorus (mgL-1) target
Short-term 2.0 0.2
Long-term 1.0 0.1

Long-term (over 25-40 years) load reduction targets for nitrogen and phosphorus have been established through the Swan Canning Water Quality Improvement Plan. Although performance against these nutrient load reduction targets is not reported on annually, sub-catchment nutrient reports are available each year to provide information on nutrient loads from monitored sub-catchments. The nutrient load reduction targets guide long-term investment to improve water quality in those catchments contributing the greatest loads of nutrients to the river system.

Sub-catchment nutrient reports

Data that is collected fortnightly as part of the catchment water quality monitoring program is used to determine the nutrient concentrations and loads entering the Swan Canning Estuary. Long-term trends in this nutrient data are calculated every five years. However, calculations of total nitrogen (TN) and total phosphorus (TP) loads are used to report annually against catchment nutrient targets.

Five-yearly reporting

Nutrient data collected from 15 priority sub-catchments is compiled into 'catchment nutrient reports', which are produced every five years. In these reports, long-term (since 1999) trends in total nitrogen (TN) and total phosphorus (TP) concentrations are calculated and used to evaluate the effectiveness of management actions.

Annual update

The annual re-calculation of nutrient trends for each catchment is not appropriate due to the high inter-annual variability in nutrient concentrations/loads (which are very dependent on rainfall patterns). However, reporting of annual nutrient concentrations and loads from each catchment are calculated each year to track progress against targets. As a result, the front page of each five-year catchment report is updated annually to provide a catchment-by-catchment measure of annual TN and TP concentrations and loads entering the Swan Canning Estuary.

The five-yearly and annual nutrient reports for each sub-catchment are available below.



Ecological health

Measures of ecological health complement water quality monitoring and reporting and provide more information about the overall health of the waterway.

The Department of Biodiversity, Conservation and Attractions (DBCA) has worked with project partners at Murdoch University and DWER to develop approaches to monitor fish and seagrass communities as indicators of ecosystem health.

Monitoring and evaluating fish communities

DBCA continues to partner with Murdoch University to annually sample and report on fish communities as an indicator of the condition of the Swan Canning Estuary, with contractual arrangements extending until 2020.

Murdoch University developed the Fish Community Index over five years (2007-12) in collaboration with the State Government. The index uses a suite of fish metrics, including diversity and the number of species, to characterise the fish community and its response to estuarine condition. The index does not focus on individual populations or measure biological performance or health of any individual fish species.

The primary purpose of the Fish Community Index is to provide an ecological indicator of estuarine condition that complements existing water quality monitoring and evaluation. The index is applied annually as part of an on-going monitoring and reporting framework.

Fish communities have been monitored in summer and autumn at six nearshore and six offshore sites in the upper, middle and lower Swan, as well as in the lower Canning, since 2012.

The latest (2018) report and historic reports are available for download at the bottom of this page.

Seagrass health and distribution

Seagrasses are some of the most productive organisms in the world with productivity rates that can be twice that of forests. They play a role in maintaining oxygen levels at the sediment/water interface, support diverse and productive faunal assemblages and are an important food source for animals such as WA’s iconic black swan.

In the Swan Canning Riverpark there are three main species of seagrass, with paddleweed (Halophila ovalis) being the dominant species.

DBCA has worked with DWER to develop a robust and easily repeatable method of surveying seagrass species composition and percentage coverage at sites in the lower Swan and Canning estuaries. This is coupled with monitoring of seagrass response to environmental pressures. Insights into seagrass health and distribution provided by this monitoring and evaluation program provide a useful complement to existing water quality reporting and will allow management policies to be specifically targeted at improving the resilience of seagrass in the Swan Canning Estuary.

Two reports have been released describing the projects and their results to-date.