If I recall, this quest has some funny bugs. I ran into a few when I did mine, where the moonstone was no where to be seen but I would have mines in the river.
Drop the quest and re-pick it up, that is what fixed it for me. What is suppose to happen is you chase the bugger down the river and catch her.
Here's some notes on it from WoWWiki:
Notes
If you don't see the Moonstone on the altar, wait a few minutes for it to respawn, another Druid is doing the quest.
If you have the PVP trinket [Insignia of the Alliance] or [Medallion of the Alliance] or anything else that will remove a stun effect ([Free Action Potion]), consider wearing/using it as Rizzle Sprysprocket will sap you after she takes the Moonstone. However, note that this will shorten the quest considerably. Many have had fun chasing her down the river.
When Rizzle jumps off the cliff, she'll swim south down the river.
Shift into Cat Form to reduce fall damage and then quickly switch into Aquatic Form to catch up to her.
Rizzle drops two kinds of bombs. One will explode and launch you out of the water, the other will freeze you in place. Remember that switching forms will remove the frost nova, so switch out and back into Aquatic Form to continue the chase.
There are some speed enhancers in the water to help you catch up to Rizzle.
There is a bug where, if you fall in the river before picking up the moonstone, Rizzle will drop ice grenades on you as you swim down the river, even though you haven't actually encountered her yet.
or Here's a Tip from Allakhazam:
Precison Coordinates: 14.1, 47.8
(1) Teleport to Moonglade
(2) Fly to Talrendis Point, Azshara
(3) Ride North, along the East side of the river
(4) Click on the Moonstone and get stunned for 8sec
(5) Hop on your mount, or use dash or travel form and go South down the East side of the river
(6) When you see her using Track Humanoids, jump in and cut her off
Edited, Nov 5th 2008 5:54pm by
Night Circle
GryphonHide