yep - that is a great way to do it as well.I've done my river a bit different, I've placed the station and a curvy track completely under terrain and I've used terrain tools to work out the river afterwards . this way you can avoid appearing track edges entirely. you can also use it to design your ride, not just an improvisated river.
[url]http://thumbnails101.imagebam.com/54529/e507ac545289727.jpg[/URL] [url]http://thumbnails101.imagebam.com/54530/24b054545290114.jpg[/URL]
(would be fun to see the waterfall element as ride. whaaaaaaaa)