Where Adelaide’s water comes from

Rain on the ridge, water in the city

Rain in the Mount Lofty Ranges rises with the ground. The Department for Environment and Water’s technical note on the Western Mount Lofty Ranges, its note 2021/11 published in October 2021, puts total annual rainfall at about 400 mm at the lowest elevations and more than 1,000 mm at the highest. The Bureau of Meteorology’s station records show the same shape. Mount Lofty’s weather station, at 685 metres, averages 963.2 mm a year over its 15 years of record from 2009 to 2026 , and Stirling, behind the crest, averaged 1,191 mm over 80 years of record ending in 1964. Adelaide’s Kent Town station, at 48 metres, averages 547.1 mm over 41 years from 1977 to 2020 , Mount Barker averages 761.9 mm , and Murray Bridge, out on the river plain at 33 metres, averages 347.9 mm. Year to year the falls vary: in 2019-20 the note records 907 mm at Hindmarsh, 4% above average, and 851 mm at Mount Bold, 6% above average. The crest station therefore takes close to twice the city’s yearly rain, and more than twice the river plain’s.

The note puts the share that rain provides: the prescribed area’s water resources supply around 60% of metropolitan Adelaide’s water requirements on average, and about 75% of the state’s population depends on them. SA Water’s reservoirs are the state’s main water storage, and at full capacity they hold almost 200,000 megalitres, just under a year of supply for the metropolitan area; they can also store River Murray water when demand is high. SA Water records daily information on each reservoir in the Mount Lofty Ranges catchment.

The area the note describes lies 10 km east of Adelaide. Its eastern parts hold the highest ground and form the upland eastern edge of the watershed , while the South Para, Little Para and Torrens drain its northern and central country, and the Onkaparinga and Myponga drain the south; all of them flow west to Gulf St Vincent. Groundwater and surface water are both prescribed resources under the Landscape South Australia Act 2019, managed under a water allocation plan adopted in 2013.

The reservoir reserves you can visit

SA Water has opened ten reservoir reserves to the public since Myponga led the way in April 2019 , and SA Water reported in May 2023 that more than a million visitors had come through their gates. Some rules hold at every reserve: swimming and immersion in the water are not permitted at any reservoir, because they mean prolonged contact with the drinking water; dogs, other than assistance dogs, are not permitted; horse riding is not permitted; and camping is not permitted, since the reserves open and close at fixed hours and offer nowhere to stay overnight.

SA Water sets out what each reserve allows, and where a permit is needed to fish.

Every reserve closes on Total Fire Ban days, and also for maintenance and operational work, or when public safety calls for it. Opening hours are 7:30 am to 5:00 pm in standard time and 7:30 am to 8:00 pm during daylight saving, with different hours for Barossa, Bundaleer, Tod and Warren, and for the Mount Bold dam wall. A valid fishing permit is required at Bundaleer, Happy Valley, Myponga, South Para, Tod, Warren, Aroona Dam and Beetaloo, and only recreational fishing is allowed. SA Water owns and manages the reserves on behalf of all South Australians, to keep safe, clean drinking water flowing to more than 1.7 million people.

Hope Valley is worth a closer look, because SA Water’s page shows it working unlike the others. The reservoir was completed in 1873 as Adelaide’s second, and it is now the oldest still in operation and the smallest active one; its reserve was the first metropolitan reservoir reserve opened to public access. It holds 2.9 gigalitres, which SA Water likens to about 1,400 Olympic swimming pools. It takes no surface water from its own catchment: water is diverted at the Gorge Weir on the River Torrens, and reaches the reservoir through a tunnel from Kangaroo Creek Reservoir. It is one of 16 reservoirs that help supply more than 1.7 million South Australians , and Hope Valley’s own page adds Christmas Day to the days its gates stay closed.