❓ A WA parliamentary question on notice addresses the Minister for the Environment regarding groundwater resources in the Perth region, specifically concerning sustainable yield, freshwater content, and annual recharge estimates outlined in the state water strategy. The Minister's response clarifies the data's scope and methodology.
AnsweredQoN 1573Legislative Council
QuestionView source ↗
I refer the minister to estimates about ground water resources published in the state water strategy and ask - (1) How was the estimate arrived at for the sustainable yield of ground water resources and current use in the Perth region, as shown on page 6 of the strategy? (2) How much of the estimated yield and current use reflects fresh water? (3) What is the total estimated annual recharge of ground water resources from the Perth region, including water allocated for the environment? Hon TOM STEPHENS
AnswerView source ↗
The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(1) How was the estimate arrived at for the sustainable yield of ground water resources and current use in the Perth region, as shown on page 6 of the strategy? (2) How much of the estimated yield and current use reflects fresh water? (3) What is the total estimated annual recharge of ground water resources from the Perth region, including water allocated for the environment? Hon TOM STEPHENS replied: The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(2) How much of the estimated yield and current use reflects fresh water? (3) What is the total estimated annual recharge of ground water resources from the Perth region, including water allocated for the environment? Hon TOM STEPHENS replied: The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(3) What is the total estimated annual recharge of ground water resources from the Perth region, including water allocated for the environment? Hon TOM STEPHENS replied: The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
Hon TOM STEPHENS replied: The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(1) How was the estimate arrived at for the sustainable yield of ground water resources and current use in the Perth region, as shown on page 6 of the strategy? (2) How much of the estimated yield and current use reflects fresh water? (3) What is the total estimated annual recharge of ground water resources from the Perth region, including water allocated for the environment? Hon TOM STEPHENS replied: The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(2) How much of the estimated yield and current use reflects fresh water? (3) What is the total estimated annual recharge of ground water resources from the Perth region, including water allocated for the environment? Hon TOM STEPHENS replied: The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(3) What is the total estimated annual recharge of ground water resources from the Perth region, including water allocated for the environment? Hon TOM STEPHENS replied: The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
Hon TOM STEPHENS replied: The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
The Minister for the Environment provided the following reply - (1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(1) The figure on page 6 refers to the Perth basin, not the Perth region. The sustainable yield is based on local rainfall recharge over a ground water subarea. All subareas over the Perth basin are tallied. Annual local rainfall and estimates of local rainfall recharge rates were used in each subarea. Estimates are preliminary and are subject to more detailed investigation and planning. Usage is based on the Water and Rivers Commission’s water licensing system and metering of large users. (2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(2) Of the estimated total water yield of 1 937 gigalitres per year, 98 per cent - 1 909 gigalitres per year - is fresh water. The current use of 749 gigalitres per year represents fresh water use. (3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
(3) The estimated annual average recharge of ground water for the Perth basin is 2 300 gigalitres per year under normal climatic conditions, where an average of 20 per cent of the rainfall recharge has been set aside for the environment and prevention of salt water intrusion from the ocean. In some subareas, up to 40 per cent of the rainfall recharge is set aside for the environment - Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
Hon Simon O’Brien: You would not get 40 per cent. Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
Hon TOM STEPHENS: Where? The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
The PRESIDENT: Order, members! Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
Hon TOM STEPHENS: In some subareas where the watertable is deep, the figure can be as little as 10 per cent. The estimates are refined after detailed investigations as resources are developed.
Explore WA Government Data
Search the full archive in the free dashboard, or query programmatically via API.
Explore more
Government Gazette
Appointments, regulatory notices, planning changes.
Hansard
Debates, questions, speeches and sentiment.
Tabled Papers
Reports and documents tabled in Parliament.
Committees
Committee profiles and recent reports.
Regulations
Subsidiary legislation with filters and summaries.
Bills
Proposed laws and parliamentary progress.
Acts
Current WA legislation and summaries.
Explanatory Memoranda
Bills with EMs (text/PDF) available.
Members
MP profiles, party breakdown and rankings.
Pollie Rankings
Data-driven rankings across 19 categories.
Amendment Chains
Track how schemes and regulations evolve over time.