You can do this route as a out and back or a loop if you follow the track which uses trails not shown on the map. This is an excellent hike with incredible views of Alta, Brighton, Heber Valley, Salt Lake Valley, all the lakes nearby and all the surrounding area. Take it easy if you aren't use to the altitude. Dogs are not allowed because of watershed. This is moderate to difficult for most hikers but not too hard if you take your time. During July and August the wildflowers are beautiful and the photography is excellent. Plan on taking a bit more time than the distance would suggest since it is up and down hill and there are many places to rest and enjoy the view!
The trailhead, which is named the Grizzly Gulch trailhead on the Alta summer trail maps, is shown as being near the summer information booth on the north side of the road. A few feet up the trail is a sign that indicates it's the Alta-Brighton trail, so maybe both are correct. I hiked it today to Twin Lakes Pass and then followed the Wolverine ridge east to Catherine's Pass. There was still lots of snow towards the upper reaches of Grizzly Gulch and on the northwest faces of the ridges. There was very light traffic until I hit Tuscrora and Catherine's pass.
The trail can be a bit difficult to navigate with a gate across it at one point and then the multiple spur trails near the mine. I originally thought about giving it 5 stars, but then I remembered the power lines somewhat spoiling the view of twin lakes.
The trails climbs steadily up to Twin Lakes Pass. The trail mostly follows an old mine road until the last 1/2 mile or so. Twin Lakes pass has great view of both Big and Little Cottonwood Canyon. I believe this trail is also called the Alta-Brighton