Frequently Asked Questions

Before you spend time writing an email to us, you might find your question has been asked before. Look in the list below to find out. If you still want more, please contact us using the feedback link.

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Why can't I find the place or surface water storage I'm interested in? Why is a city or town not listed in Water Storage?
We currently process data for selected water data providers in each state and territory. We are working to increase the number of water storages shown on this site and to expand the coverage of Australia's cities and supply systems. We will announce new water storages as they are added.

The initial focus is on publicly-owned water storages that can hold at least 1000 ML of water. The site currently includes storages which are associated to capital cities and key supply systems as well as to states and drainage divisions (Hint: if you can't see storages associated to any of these place try clicking on the icons on the left hand side above the map or type in the name of the storage or place in the box next to the search button).
When I choose the city button, I can see capital cities and other places. What are these other places?
The other places represent key supply systems. In most cases they are groups of storages serving major water markets (NWC National Water Markets Report, 2009). Other notable groupings are the hydroelectric power generation systems in Tasmania.
When I view Australia, I can divide it into Drainage Divisions. What is a Drainage Division?
Australia's drainage divisions and river basins were formally defined by the Australian Water Resources Council in the early 1960s and have been the basis for the study of Australian hydrology since then. The 12 drainage divisions were defined by both the major topographic features of the continent and the main climatic zones to give broadly homogeneous hydrologic regions. The 245 river basins within drainage divisions are defined by major watershed lines. The digital data set of drainage divisions and river basins is available from Geoscience Australia, the national mapping agency.
Why are the numbers you are reporting different to those reported by the water utilities?
We have standardised all data received from suppliers across Australia. In doing so, some figures will be different (see the glossary for the description of volume reported). Typical reasons for difference include:
  • Some suppliers report against total capacity (including the dead storage) whereas we report against the accessible capacity.
  • Some organisations smooth the data they publish meaning they end up with slightly different values to those in our system.
  • We may not have all the information or rules to exactly reproduce the calculation of the water stored in a city system.

More detail on specific differences between this product and a particular data provider are listed on the provider specific information pages. If you note a difference please let us know via feedback.

How often is information updated? Why do some storages have information that is months old?
The Bureau receives data at many frequencies (by the minute, hour, day, and week). We update the Water Storage page as soon as new data has been received, checked and processed. Typically, the latest data will have been observed yesterday or the day before yesterday. (Hint: the details tab shows the date of latest reported data). In some cases data is commercially sensitive. This is particularly the case where dams are used for hydroelectric power generation in Tasmania or the Snowy Hydro Scheme. In these cases there is a two month delay before we can publish data for an individual hydroelectric dam. However, in some cases we are allowed to report up-to-date volumes for groups of commercially sensitive water storages (e.g. there are 10 systems of hydroelectric storages in Tasmania).
When it rains what changes will I see in water storages?
Some water storages respond quickly when it rains on their catchment areas, others more slowly. It may take a few days to a week for rainfall to increase the storage level and volume. You can find more information on where the rain fell and how heavily at forecast rainfall.
Am I able to use the values published for my own purposes or download the data?
You are able to use many of the values displayed because data is supplied by many providers under a Creative Commons licence. For others, you may have to contact them to discuss using their data. You can find out more at: copyright and creative commons information. We are working to add a data download service to this interface. Further information will be provided when available.
How can I find out what the water in the storage is being used for?
The Bureau does not receive sufficient data to answer this question. However, in most cases you should be able to find out more detailed information from the owner or operator of the storage. (Hint: the owner or operator is listed in the summary tab when you have a single water storage selected).
Who is involved in measuring, storing and presenting the data on this product?
The Bureau now receives water information from over 250 organisations around Australia. These organisations maintain the equipment, systems and staff to observe our water resources (e.g. flow in rivers, water levels in reservoirs and aquifers, rates of urban water use). The Water Act 2007 requires these organisations to send this information to the Bureau. (Hint: for more information on these organisations and what they measure, you can visit the water regulations online tool). The Bureau loads the water data into the Australian Water Resources Information System. The measurements arrive in many different forms and one of the key steps we take is to standardise the data. For example, all water storage levels are converted into metres above sea level (mAHD). Some fundamental quality checks are then made. For example, the water level must not be lower than the lowest point in the water storage. Finally, we prepare a daily water level for each water storage and calculate the total volume of water stored for each storage, city and region in the system. This data is then published for you to view using the Water Storage user interface.
How are volumes for regions, systems and cities calculated?
To calculate the 'aggregated volume' for a collection of storages on a particular date, we add up the most recent volume for each storage in the collection - provided the information is less than 30 days old. If the information is more that 30 days old it is left out of the calculation. If too many of the storages are left out of the calculation, then the aggregated volume is not considered a valid estimate of the volume held in the region. This occurs if the accessible capacity of the missing storages is greater than 7% of the capacity of the region.

If a valid aggregated volume cannot be calculated today, the system will publish the latest valid aggregated volume - provided one is available within the last 7 days. If there has not been sufficient data to calculate a valid aggregated volume within 7 days, then the volume and percentage volume for the place will be shown as N/A (not available).

Note that an individual water storage may hold more than 100% of its accessible capacity on a given day. However, the volume of water above 100% is considered to be in transit rather than in storage. Therefore, the volume a water storage can contribute to the aggregated volume of a place is capped at the accessible capacity of that storage.
How are the percentages calculated?
To calculate the current percent full we take the current volume for a storage or place and divide it by the current accessible capacity. To calculate the percentage last year, as shown in the Snapshot tab and Details tab, we take the volume at the same time last year and divide it by the accessible capacity last year. Percentages shown on the graph are slightly different; they are always calculated using the current accessible capacity.

The percent change, is the change in volume as a percentage and is equal to the difference between the current and previous year volume, divided by the current accessible capacity (this is the same as the percent change seen on the Graph).

You may therefore notice that for some storages and places the percentages will differ depending on where on Water Storages you look, and that the percent change will not equal the difference between the percentages shown in the Snapshot. This will occur, for example, when the accessible capacity for a storage or place has changed over time.

Enlarged Cotter Dam

How much bigger is the enlarged Cotter Dam?
The enlarged Cotter Dam has an accessible storage capacity of 76,197 ML, which is nearly 20 times its original capacity of 3,847 ML.
What are the benefits of the Cotter Dam Enlargement Project?
The additional storage volume increases the Territory’s accessible water storage capacity by 35% and will play a key role in helping to secure the region’s future water supply.
Why does the storage volume of the Cotter Dam change significantly on the 25 February 2013?
In 2013 the total accessible storage capacity of the Cotter Dam was enlarged from 3,847 ML to 76,197 ML. During this process a new minimum supply level and capacity table were applied to the Cotter Dam storage as from 25 February 2013. The change has caused a substantial rescaling of the graph post 25 February 2013. The graph below shows Cotter Dam’s storage volumes at original scale prior to this change.
For further information on how these values are calculated please see FAQ: How are the percentages calculated?
Graph showing the 2009 to February 2013 storage volumes
Change in storage volumes of the Cotter Dam (as at 25 February 2013)
Note: storage volume may be read as either Accessible Volume (ML) or Percentage Full (%)

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