Farmer Jacques Ruffieux, whose 130 cattle need 10,000 litres of water per day, said it had been a painful year marked by very little rain.
“Since Jun 27, we only had 30 litres, it’s nothing,” said the farmer, adding the army arrived just in time.
“We were a day and half from not having anything at all, it was very close,” he said.
Swiss territorial army commander Mathias Tuescher said six helicopters had been mobilised for the effort, which will run until Aug 19.
Overall some 400,000 tonnes of water could be dropped by the helicopters into the reservoirs, he said, with 1.5 tonnes delivered each trip.
The operation was also carried during the droughts of 2015 and 2018.
“With global warming, there is a probability that this kind of mission would be more frequent in the future,” he said.