Two crews from Chorley and Darwen attended the report at around 1.30pm on July 3 near to the canal bridge at Withnell Fold.
The farmer and the firefighters successfully coaxed the animals back to the farm using food.
A spokesman for the fire service said: "We responded to a report of fifteen juvenile cows stranded on a ledge in shallow water in the canal, unable to get out.
"The cows often go along to the canal for a drink and this time went a little further than usual.
"We ensured the safety of the animals as they were coaxed back to a nearby field by their owner."
No cows were injured during the incident.