Perth weekly water update - 19 November 2021
| Target | Actual | |
|---|---|---|
| November water use to date |
17.0 billion litres |
15.9 billion litres |
| Dam storage levels | N/A | 63.1% |
| Monthly streamflow into dams | N/A | 4.74 billion litres |
| November rainfall to date | 22.40mm (November average rainfall 1876-2016) | 41.24mm |
| Note: 1 billion litres = approximately 400 Olympic swimming pools. Please note the figures in this table are rounded (except for rainfall) to the nearest whole number. | ||
Water use
Average water use over the past week was 871 million litres per day – below the demand forecast of 913 million litres per day.
Daily water use for the last 5 days
| Date | Actual water use (million litres) | Forecast water use (million litres) |
|---|---|---|
| 19/11/2021 | 769 | 924 |
| 18/11/2021 | 868 | 924 |
| 17/11/2021 | 927 | 924 |
| 16/11/2021 | 870 | 924 |
| 15/11/2021 | 982 | 896 |
| Note, water use is calculated up to 8am each day for the previous 24 hour period. | ||
Since 1 July 2021 to date, we have used 95.31 billion litres of water – which is 1.76 billion litres below the forecast target for this period.
Dam levels (total for 15 dams)
The dam storage levels are slightly down on last week and are sitting at a combined 63.1 per cent* of full capacity.
*Please note some dams are filled from different sources - dam levels include the transfer of groundwater and desalinated seawater from treatment plants as well as streamflow (that comes from rainfall). As we use many different sources of water, dams are no longer an accurate indicator of the health of Perth's overall water supply situation.
Streamflow (total for 15 dams)
From 1 May 2021, the dams have received 137.4 billion litres of streamflow. The post-1975 average for the May to April period (called the streamflow year) is 178.2 billion litres.
Sprinkler roster compliance
Since 1 January 2021, we have taken a total of 4,904 actions (warnings + fines) compared with 5,076 actions for the same period in 2020.
Annual rainfall
Perth has received 881.6mm of rainfall since 1 January 2021. The average (1876-2016) rainfall for the same period to the end of November is 831.4mm.
General water news
The State Government has announced a proposal to align Perth and Mandurah garden bore users’ sprinkler roster with the scheme sprinkler roster (two watering days per week). This is in response to the impacts of climate change and increasing groundwater use.
Alignment of the domestic garden bore and scheme water rosters will save up to 30GL (gigalitres or billion litres) per year, stabilising water tables in urban areas and increasing water availability to street trees and important urban wetlands, such as Perry Lakes, Herdsman Lake, Lake Gwelup, Carine Swamp, Star Swamp, North Lake and Bibra Lake.
It is estimated that garden bores collectively draw about one fifth (22 per cent or around 90GL) of groundwater taken from the aquifers in the Perth to Mandurah area to use outdoors, mostly for irrigating lawns and gardens.
Garden bore users generally use about three to four times more water on their gardens in comparison to scheme water users.
To learn more and have your say, visit the Department of Water and Environmental Regulation's website.