❓ A WA parliamentary question addresses Swan River water quality, querying oxygen depletion, remediation effectiveness, and the absence of algal blooms. The Minister's response disputes the extent of oxygen depletion and cites multiple factors influencing algal growth.
AnsweredQoN 1076Legislative Council
QuestionView source ↗
SWAN RIVER — WATER QUALITY
(1) Is the minister aware that data from the Swan River Trust and the Centre for Water Research independently show that water below about two metres in the Swan River estuary from Point Walter to Guildford and the Canning estuary to Wilson has been oxygen depleted for the last four months and is essentially dead and awash with nutrients? (2) Is the minister aware that the only active remediation action supported by the government, the oxygenation of small stretches of the upper Swan, is regarded by scientific experts as ineffective and is not even switched on at the moment? (3) Does the minister agree that the only reason we are not seeing massive algal blooms at the moment is that tannins in the water are acting to curtail algal growth by robbing the water of light; and, if not, does the minister have an alternative explanation? Hon HELEN MORTON
(1) Is the minister aware that data from the Swan River Trust and the Centre for Water Research independently show that water below about two metres in the Swan River estuary from Point Walter to Guildford and the Canning estuary to Wilson has been oxygen depleted for the last four months and is essentially dead and awash with nutrients? (2) Is the minister aware that the only active remediation action supported by the government, the oxygenation of small stretches of the upper Swan, is regarded by scientific experts as ineffective and is not even switched on at the moment? (3) Does the minister agree that the only reason we are not seeing massive algal blooms at the moment is that tannins in the water are acting to curtail algal growth by robbing the water of light; and, if not, does the minister have an alternative explanation? Hon HELEN MORTON
AnswerView source ↗
I thank the member for some notice of the question. (1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(2) Is the minister aware that the only active remediation action supported by the government, the oxygenation of small stretches of the upper Swan, is regarded by scientific experts as ineffective and is not even switched on at the moment? (3) Does the minister agree that the only reason we are not seeing massive algal blooms at the moment is that tannins in the water are acting to curtail algal growth by robbing the water of light; and, if not, does the minister have an alternative explanation? Hon HELEN MORTON replied: I thank the member for some notice of the question. (1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(3) Does the minister agree that the only reason we are not seeing massive algal blooms at the moment is that tannins in the water are acting to curtail algal growth by robbing the water of light; and, if not, does the minister have an alternative explanation? Hon HELEN MORTON replied: I thank the member for some notice of the question. (1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
Hon HELEN MORTON replied: I thank the member for some notice of the question. (1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
I thank the member for some notice of the question. (1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(2) Is the minister aware that the only active remediation action supported by the government, the oxygenation of small stretches of the upper Swan, is regarded by scientific experts as ineffective and is not even switched on at the moment? (3) Does the minister agree that the only reason we are not seeing massive algal blooms at the moment is that tannins in the water are acting to curtail algal growth by robbing the water of light; and, if not, does the minister have an alternative explanation? Hon HELEN MORTON replied: I thank the member for some notice of the question. (1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(3) Does the minister agree that the only reason we are not seeing massive algal blooms at the moment is that tannins in the water are acting to curtail algal growth by robbing the water of light; and, if not, does the minister have an alternative explanation? Hon HELEN MORTON replied: I thank the member for some notice of the question. (1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
Hon HELEN MORTON replied: I thank the member for some notice of the question. (1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
I thank the member for some notice of the question. (1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(1) The regular weekly monitoring by the Swan River Trust and Department of Water does not support the conclusion that water below two metres between Point Walter and Guildford has been oxygen depleted over the last four months. Indeed, much of the river in this area has had dissolved oxygen concentrations greater than six milligrams per litre, which is well within the ideal range, for much of this period. Low dissolved oxygen levels in the lower Swan River are not unusual at this time of year. Over the past four months seasonal changes to environmental conditions have resulted in changes in oxygen concentrations. (2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(2) Management and protection of our Swan and Canning River system is a complex and ongoing task. The Swan River Trust, community groups, industry and state government agencies are working to reduce nutrients entering our rivers through the restoration of catchments and river foreshores. Nutrient intervention technology trials continue to be a major focus. Projects such as oxygenation provide a more immediate and localised improvement in water quality. (3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
(3) No; algal blooms are the result of many complex and interacting factors, including light penetration, nutrient concentration, water column mixing, water temperature, wind speed and algal speciation.
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