At least seven deer are thought to have fallen in the Bridgewater Canal in 10 days.
Firefighters were called to rescue two animals in the water on Friday. One sadly died.
The first deer was spotted in the canal near Booth Hall Way in Worsley.
Passers-by managed to rescue it using a rope.
Another deer further down the canal died. A passing earlier cyclist jumped in to try and save it.
Vicky Martin saw a post on Facebook about the animals and rushed to the canal to try and save them.
"I got down there and two men had just arrived, one came with a rope," she said.
"We found the deer, we walked half a mile to the canal and I rang the emergency services.
"We managed to put a rope around its neck and pull it out. We kept it calm on the floor for a minute or so then it got up and ran off.
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"Then another man passed us and said there is another there in the water but I can't pull it out on my own."
Building work is thought to have startled a number of deer.
Vicky added: "There have been reports of seven deer in 10 days falling in the canal.
"Once a deer gets into the water they are so scared they swim until they exhaust themselves to death."
A spokesman for Greater Manchester Fire and Rescue Service said: "We were called at 7.18am to reports of deer stuck in the canal on Booth Hall Way in Worsley.
"The RSPCA arrived at 9.46am and removed a carcass from the canal."
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