How do I breed a River Dragon in DragonVale?

Looking for the fastest breeding combination to hatch the River Dragon? Grab an intertube! We've got all of the details you need to know below:

River Dragon

Breeding Pair: Earth + Water (Another easy one, Backflip must be feeling guilty...)

Breeding Time: 13hours or 10 hours 24 min (with upgrade)

Availability: Unlimited

Type: Water, Earth

Price: 900 Gems (Would you accept an IOU?)

Note that this dragon is a possible outcome of attempts to breed the Century Dragon, so if you are working on that one, you might get this one for free.