❓ A parliamentary question addresses the hydrogeochemical impacts of groundwater extraction from the Gnangara mound on wetlands, infrastructure, and acid sulfate soil formation, with the government outlining monitoring, management, and replenishment efforts.
AnsweredQoN 953Legislative Council
QuestionView source ↗
GNANGARA MOUND GROUNDWATER LEVELS
I refer to the well-studied phenomenon on the Swan coastal plain that falling groundwater levels exposes organic lake and wetland sediment, an acid sulfate soil, and contributes to low groundwater pH in areas down gradient of the lakes and wetlands of the Gnangara mound. (1) What are the hydrogeochemical impacts on wetlands and lakes throughout the northern metropolitan area that result from extracting water from the Gnangara groundwater mound? (2) What is the potential damage to infrastructure due to acidity and iron levels in very low pH groundwater? (3) What is the government doing to correct declining groundwater levels across the Gnangara mound? (4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON
I refer to the well-studied phenomenon on the Swan coastal plain that falling groundwater levels exposes organic lake and wetland sediment, an acid sulfate soil, and contributes to low groundwater pH in areas down gradient of the lakes and wetlands of the Gnangara mound. (1) What are the hydrogeochemical impacts on wetlands and lakes throughout the northern metropolitan area that result from extracting water from the Gnangara groundwater mound? (2) What is the potential damage to infrastructure due to acidity and iron levels in very low pH groundwater? (3) What is the government doing to correct declining groundwater levels across the Gnangara mound? (4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON
AnswerView source ↗
I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(1) What are the hydrogeochemical impacts on wetlands and lakes throughout the northern metropolitan area that result from extracting water from the Gnangara groundwater mound? (2) What is the potential damage to infrastructure due to acidity and iron levels in very low pH groundwater? (3) What is the government doing to correct declining groundwater levels across the Gnangara mound? (4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(2) What is the potential damage to infrastructure due to acidity and iron levels in very low pH groundwater? (3) What is the government doing to correct declining groundwater levels across the Gnangara mound? (4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(3) What is the government doing to correct declining groundwater levels across the Gnangara mound? (4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(1) What are the hydrogeochemical impacts on wetlands and lakes throughout the northern metropolitan area that result from extracting water from the Gnangara groundwater mound? (2) What is the potential damage to infrastructure due to acidity and iron levels in very low pH groundwater? (3) What is the government doing to correct declining groundwater levels across the Gnangara mound? (4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(2) What is the potential damage to infrastructure due to acidity and iron levels in very low pH groundwater? (3) What is the government doing to correct declining groundwater levels across the Gnangara mound? (4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(3) What is the government doing to correct declining groundwater levels across the Gnangara mound? (4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(4) How would the annual extraction of 165 gigalitres of water from the Gnangara mound impact on the potential for the creation of acid sulfate soils? Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
Hon HELEN MORTON replied: I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
I thank the member for some notice of this question. The following information has been provided by the Minister for Water — (1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(1) Both the climate and water abstraction from the Gnangara mound have the potential to trigger hydrogeochemical changes to wetlands, such as a decline in pH, an increase in metal concentration and possibly eutrophication. (2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(2) Prolonged exposure to acidic groundwater has the potential to corrode concrete structures. High iron levels in groundwater when exposed to the air can cause rust-coloured staining on infrastructure. (3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(3) As well as carefully monitoring and managing extractions from the Gnangara mound, the government will also soon officially open a highly treated waste-water replenishment trial that will prove up technology that will eventually allow significant replenishment of extracted water from the aquifer. (4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
(4) It is expected that the extremely poor winter rainfall could mean that some wetlands will be drier this summer than they have been in previous years. The Department of Water is currently completing its detailed assessment of which wetlands these are likely to be. Drying wetlands have the potential for acidification. Should there be a return to an average winter rainfall next year, the wetlands are not likely to suffer permanent loss.
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