Water and environmental police had just carried out a joint exercise on Lake Aegeri when a boy informed officers the animal was in trouble in the water, the force said in a statement.
Officers used the Bella patrol boat to track down the roe deer, locating it a long way from the safety of shore.
Kovaldas Balciauskas, an expat based in Oberägeri told The Local via email be had been playing tennis when the deer came charging through the village and slammed into the fence surrounding the tennis courts.
"We continued to play tennis and the deer remained in the creek for about 20–30 minutes before it ran out of the mouth of the creek and proceeded to swim away from shore," he wrote.
When he and his friend Will Pendered saw the animal was struggling, they decided to jump in a row boat to see if they could help the animal.
"If it began to struggle we would have intervened but it was unnecessary," Balciauskas wrote, noting police vessels were already intervening. His video footage above shows the rescue in progress.
Photo: Zug Police
The animal was returned to shore shortly afterwards.
“Wildlife officers returned the deer to the forest where it could recover from the shock,” police said in their statement.
“This was an unusual operation for water police and environmental protection officers which, to the delight of everyone involved, ended happily," they said.