The iconic Captain Cook Memorial Jet will be turned off tomorrow (15 January) at 2:00 pm due to the drought.
Lake Burley Griffin water levels influenced the decision made by the National Capital Authority (NCA), which said the jet will not be operational while current weather conditions continue.
The lake is currently down 500 mm from its normal levels, which can affect the running of the jet’s pump, the Director of Estate Management, Peter Beutel, said.
“We do not take this sort of decision lightly as the jet is near and dear to many Canberrans,” he told Region Media.
“We are pre-emptively turning the jet off to reduce the risk of any damage to the pump set as a result of cavitation, as the potential for air to be sucked into the pump increases and air in a water pump can be quite devastating. It creates a lot of vibration and can vibrate all the parts of the pump apart. We are just taking a precautionary approach.”
The lake, which is down to 29 gigalitres from its usual 33, will need to return to a safe level before the pump is switched on again.
“I don’t know [when it will restart], it really depends on how much rain we get and when,” Mr Beutel said.
“There is rain forecast for Thursday but we really do not expect it to be anything close enough to have any effect. Essentially we are waiting for the lake level to come back up again and it will require substantial rain for it to come back up to a safe level.”
The jet has been plagued with problems over the last few years and was shut down in March 2019 for a few months to undergo repairs at an estimated cost of $250,000.
In 2017, it re-opened after two years of extensive repairs that were intended to return the jet’s full range. Those repairs cost around $3 million.
The jet pumps 500 litres of water per second into the air at a speed of 260 km/h, reaching heights of around 150 metres.
While the decision to switch off the jet is about mechanical safety rather than water use (as the water falls back into the lake), evaporation is significantly impacting the lake level.
“Most of the evaporation of the lake is proportional to the surface area. We have a very large lake for the volume of water that is in it, and we have a proportionally high evaporation rate for the size of our lake,” Mr Beutel told Region Media.
The iconic fountain was inaugurated by Queen Elizabeth II on 25 April 1970, almost 50 years ago, and the NCA promises it will be back.