Sioux Falls, South Dakota has a parks system that includes a loop trail. Falls Park, adjacent to the downtown, is a good starting point. And yes, there are waterfalls in this town. Below is one, though there are others in the park, too. Jasper, or quartzite, is a beautiful stone, harder than granite and nearly as hard as diamonds, and it makes up the bedrock of Sioux Falls. It was quarried and used for many of the important buildings and expensive homes in the city.
I suggest you bike around the park to the various overlooks, walk to the top of the observation tower for an overview of the park and town, then bike the downtown, and then bike the trail.
Several segments were closed in 2011 for sewer line work and bridge construction, but if you head counter-clockwise from Falls Park you'll have a lengthy open section to explore. Falls Park is numbered below in red. Biking counter-clockwise from there puts you in section 17, then 16, etc. and the green indicates an open segment.
When you get to the lengthy spillway seen below, go left...
... and you'll find yourself pedaling uphill on a series of 5 switchbacks seen from above in this photo...
...which puts you atop a levee that encircles the city. You'll pass farm fields, a prison, the airport, a golf course, and several parks. This paved trail is in good repair, and when finished, will be a wonderful loop ride. I went about 10 miles, then returned the same way for a 20 miler.
Here's a downloadable PDf map of the trail.
Souix Falls Parks and Rec site.