Bell Canyon, also known as Bell's Canyon or Bells Canyon, is a circular, glacier-carved canyon adjacent to Little Cottonwood Canyon. It's accessed from two different trailheads near the entrance to Little Cottonwood Canyon. The canyon offers a number of options to hikers, including two short, easy routes to Lower Bell Canyon Reservoir, and more strenuous hikes to a set of waterfalls and Upper Bell Canyon Reservoir. Lower Bell Canyon Reservoir is appropriate for beginners and children, the lower waterfall is a strenuous intermediate hike, and the upper reservoir is a strenuous all-day hike. I've enjoyed Bell Canyon mostly as a quick getaway or place to take the kids, but it can be a much more adventurous hiking experience depending on how far you go.
The Granite trailhead for Bell Canyon is on Little Cottonwood Road, just east of Wasatch Boulevard at about 9800 S. and 3400 E. This trailhead has toilet facilities and parking. The Boulders trailhead is located at 10245 S. Wasatch Boulevard; it has parking but no toilets. From the Granite trailhead to the reservoir is .7 miles, with a vertical rise of 560 feet. From the Boulders trailhead to the reservoir is .5 miles with a vertical rise of 578 feet.
The hike to the lower reservoir is a relatively easy climb through sage and scrub oak, and another easy trail goes around the lake, through shady woods and across a small footbridge over the creek. The wooded section of the trail is cool and refreshing in hot weather. At the reservoir you will usually find a few ducks, and it's a great place for kids to splash and throw rocks in the water. Fishing with artificial bait is allowed, but swimming and pets are not - the area is a source of drinking water.
The trail to the first waterfall begins as a service road north of the reservoir. About .1 mile up the road, a sign points to the trail proper. The trail follows Bell Canyon Creek, with a pleasant path through meadows leading to a steep granite staircase. A spur 1.7 miles from the trailhead leads to the waterfall on the left. The path to the waterfall requires descending a steep hillside with loose dirt, but the beautiful falls are a nice reward for your hiking efforts.
After the first waterfall, you can return the way to came, or continue on the to the second waterfall and upper reservoir. The official trail runs out about 1.9 miles from the trailhead, but cairns mark the way to the upper falls and upper reservoir. The upper reservoir is 3.7 miles and 3800 vertical feet above the lower reservoir. I have not ventured that far, but here are a couple of links with nice descriptions of the hike to the upper reservoir:
Be aware that the stream and waterfall are extremely powerful during spring runoff season. The water may be shallow, but it is extremely cold and flows fast enough that people can quickly be knocked down and trapped under the current. People drown every year in Utah's rivers and creeks during spring runoff season. These tragic situations can be avoided by staying well clear of the water, and not hiking near streams during periods of high runoff.