It becomes available at Level 8, and must be triggered manually by clicking on the ducks standing next to a chained-up treasure chest (near the Mushrooms).
There is no time limit for this quest. To complete it, you must gather 20 Flint Shards, 30 Clay bricks, and 10 pieces of Duckweed from your friends. Once done, it will take 1 minute, 30 seconds to make a pond for your ducks.
You will receive 35 Gems as a reward for completing the task.