It doesn't always have to be a lot of water either, just the right situation. When I was a kid there was a place we would go camping, and there was a little stream coming down the mountain, like the ones that are only a foot or so wide.
This little waterfall was right where it fed into a small creek. The creek was down a slope, so if you went down there you weren't seen from ground level, and it fed into a culvert to go under the road. It could be 100 degrees out, and if you went down to that little area with the waterfall, it could almost get chilly.