Location: Dog Lake is located in Salt Lake County, Utah, and is part of Big Cottonwood Canyon. There is two Dog Lake's in Big Cottonwood Canyon. This article will focus on the lake that straddles Mill Creek Canyon. The other less popular Dog Lake is located just east of Lake Mary. From the base of Big Cottonwood Canyon you will travel up about 9 miles. Park at the North Fork Trailhead which is just across the street form the turn off to Donut Falls. Alternatively you can come from the Mill Creek Canyon side. Just head up the canyon until the road ends, then park.
Trails: The more popular trail is the Mill D Trailhead from Big Cottonwood Canyon. The hike is about 2 miles from the beginning, to the lake. About 3/4 of the way up the trail will fork. There will be a sign pointing to Dog Lake or Desolation Lake. Follow the trail to the left. From Mill Creek Canyon there is two trails you can take. The Lower Big Water Trailhead is 3 miles in distance but is a much easier hike. You can also take the Little Water Trail which is 1.8 miles. Although the shorter hike is pretty steep and gains elevation quickly.
Other Info: There are a lot of mountain bikers that pedal the trail. The trail from the Mill Creek side is supposed to be closed to bikers every other day. Several bikers don't seem to give a crap though, and will take the trail on days when its closed. When riding downhill the bikes can get up to 25 miles per hour. So be sure to listen for bikes.
Wildlife: Moose love to loiter around the area. Often times blocking trails. Please be aware and do not try and approach them. Moose are best viewed from a distance. Moose can exceed weights of 1,000 pounds and run up to 35 miles per hour. Cow moose are most aggressive in the spring when they have young. Bull moose are most aggressive in the fall when they are breeding. Wildawareutah.org has a good write up on dealing with wildlife.
Fishing Info: The lake is too shallow and winterkills yearly. So there are no fish planted. We did see some tadpoles swimming around though.
Regulations: Ironically dog's are not allowed in Big Cottonwood Canyon. The streams are collected for culinary water. So if you have a dog outside of your car you could get a ticket. This of course doesn't affect service dogs. So you will still see the ski patrol pups wandering around. If you want to take your dog you will have to come from the Mill Creek Canyon side. On even numbered days bikes are not allowed on the Big Water Trail, and dogs must be on leash. On the Odd numbered days bikes are not allowed on the trail, and dogs may be off leash.