Attached Link: http://rex3d.net/mgriffey/waterFallTest7.avi

ok, well this Waterfall I am currently making for my job isnt made in Bryce, but thought it might be able to help you. It isn't great but Its still a WIP and the 100 frames rendered in less than 3 hours. It was done in 3dmax 7 using a few partice sprays and a Gravity Force. Im not sure if You have access to Max, but if you do or any other program with particles, I would be happy to share any settings if youd like