Water resources - Quality - Western Australia
Western Australia
What are the main pressures on surface water quality and the key findings?
Pressures on Surface Water Quality
- Dry climate and waterways with generally low flows, which are vulnerable to adverse ecosystem change and contamination from point and non-point sources.
- Geological conditions including large natural stores of salt in WA landscape.
- Population demographics (concentration in the South-west) and history of unsustainable land use practices.
- Most pressing environmental factors for WA freshwaters are linked to land clearing, salinisation, loss of riparian vegetation, eutrophication, erosion of river banks, sedimentation of channels, modification of drainage systems and contamination of rivers by pesticides and herbicides.
Main findings: Location of Water Quality problems and trends
Salinity was the most widespread surface water quality issue in Western Australia, but this may partly reflect the limited data on other water quality variables. Except for smaller coastal basins in the South-West (including Harvey, Preston, Donnelly and Shannon) almost all basins both inland and coastal were affected by salinity. Trend data identified a number of basins with increasing salinity including the Kent, Frankland, Warren, Busselton, Murray, Esperance and Shannon. Some parts of the Shannon basin also recorded decreasing salinity. The Preston was the only basin to recorded predominantly decreasing salinity trends.
Where nutrient data was available it indicated that both total phosphorus and total nitrogen exceedances were significant water quality issues in Western Australia. Only the Blackwood basin did not exceed guidelines for both total nitrogen and phosphorus. The Preston basin reported exceedances for total nitrogen but not phosphorus, while the Murray basin did not exceed guidelines for total nitrogen but did for total phosphorus, possibly associated with its high turbidity status (phosphorus is bound to suspended sediment). Trend data indicated increasing nutrient levels for the Denmark (total nitrogen), Murray and Harvey (total nitrogen and total phosphorus) basins, and decreasing levels in the Murray, Albany (total phosphorus) and Swan Coastal basin (total nitrogen and total phosphorus).
Turbidity data from only four basins were available for analysis. These indicated that the Murray and Harvey Basins had significant exceedances while the Blackwood basin did not.
pH data were also limited. Only one basin, the Harvey recorded exceedances.
Summaries presented within State and Territory reporting sections are excepts from project reports compiled by State and Territory agencies. For further information contact the Western Australia Water and Rivers Commission
Description of water quality monitoring programs
Organisations Involved
- Western Australia Water and Rivers Commission's (WRC).
- River and Estuary Investigation Branch and Surface Water Hydrology Branch (salinity data).
Management Objectives
- State established guidelines (see water quality guidelines table). Monitoring programs have evolved through responses to particular issues including eutrophication of estuaries and soil salinisation.
Sampling Methods
- Routine (regular time period) monitoring (see detailed methodology report).
Summaries presented within State and Territory reporting sections are excepts from project reports compiled by State and Territory agency personnel. To down load full project reports go to State and Territory project reports. For further information contact the Western Australia Water and Rivers Commission
The following table lists the coverage of water quality monitoring in Western Australia. Basins that had no stations used in this assessment of water quality monitoring are not listed in this table.
| Drainage Basin | Number of stations used in water quality reporting | Number of attributes for which exceedance analyses could be determined | Number of attributes for which trend analyses could be determined |
|---|---|---|---|
| WA | 156 | N/A | N/A |
| Albany Coast | 11 | 5 | 2 |
| Avon River | 5 | 1 | 1 |
| Blackwood River | 9 | 5 | 1 |
| Busselton Coast | 2 | 1 | 1 |
| Collie River | 18 | 3 | 1 |
| Denmark River | 11 | 4 | 2 |
| Donnelly River | 1 | 1 | 1 |
| Esperance Coast | 4 | 1 | 1 |
| Frankland River | 1 | 1 | 1 |
| Greenough River | 6 | 1 | 1 |
| Harvey River | 14 | 5 | 2 |
| Kent River | 2 | 1 | 1 |
| Moore-Hill Rivers | 2 | 1 | 1 |
| Murchison River | 1 | 1 | 1 |
| Murray River (WA) | 22 | 5 | 2 |
| Preston River | 13 | 3 | 1 |
| Shannon River | 5 | 1 | 1 |
| Swan Coast | 24 | 3 | 2 |
| Warren River | 5 | 1 | 1 |
Click on the basin name in the table to view a water quality report for that basin.
What is the extent of the water quality monitoring coverage?
Reported Monitoring Coverage
Data were reported from 150 stations covering 19 basins primarily within the South-West Drainage Division. Monitoring coverage for the State is primarily limited to the South-West coast Drainage division. There was a lack of monitoring coverage across the remainder of the State. Data for one variable (salinity) was available from two Indian Ocean Drainage Division basins.
The number of exceedance analyses possible per basin varied from up to five: salinity, turbidity total nitrogen, total phosphorus and pH for four basins in the more populated basins to only one (salinity) for the greater majority of basins. Trend analyses were similarly constrained by the available data. Turbidity exceedance analyses were limited to only four basins. Monitoring station density and resultant basin coverage too low to characterise the turbidity, salinity, total phosphorus, total nitrogen and pH status within a number of monitored basins.
Application of findings, information gaps and recommendations
Application of findings
The Audit assessment of surface water quality in Western Australia provides a valuable insight to current surface water quality status and assists in the identification of poor water quality 'hot spots'.
This assists environmental agencies by establishing in which key regions of south-west Western Australia inland water quality has been adversely impacted and identifies those that need to be protected.
Water quality trend information provides an indication of whether a river system is improving or degrading over time which enables environmental managers to identify at a regional scale priority areas for action and permits the efficient allocation of resources.
Information Gaps
- Unmonitored drainage divisions include the majority of the Indian Ocean, Western Plateau and Timor Sea Drainage Divisions.
- Turbidity, suspended sediment, nutrient and pH exceedances and trends were not assessed for many basins due to the short time series of available data set.
Recommendations
- Existing water quality monitoring programs (many of which were implemented on an ad-hoc basis and have undergone frequent changes to monitoring sites, sampling frequencies and measured parameters) be reviewed and changes made where appropriate to meet desired information objectives with the most efficient use of available resources.
- Water quality monitoring networks also be used to monitor changes in land use and management initiatives to provide information to managers regarding changes in water quality associated with land use change and management initiatives.
- Information on water quality trends be interpreted against catchment management activity and changes in land use.
- Monitoring of features other than water quality be explored. For example indexes of aquatic biodiversity, catchment condition, water quality, hydrology and habitat quality be further developed as environmental performance indicators for management.
Summaries presented within State and Territory reporting sections are excepts from project reports compiled by State and Territory agency personnel. To down load full project reports go to State and Territory project reports. For further information contact the Western Australia Water and Rivers Commission
Further Information
- Further information can be obtain from:
- Link to Map Maker.
Key
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