Grantsville Reservoir is a small lake in the west desert west of the Oquirrh Mountains in Salt Lake County. The lake is primarily used for irrigation water for area farmers, and can suffer large drawdowns in late summer especially during drought years. Grantsville is stocked by the DWR with Rainbow Trout.
Fishing is usually best very early in the morning or very late in the evening, when the water cools just a bit, and the bright sun is off the water. Grantsville doesn't have much cover for fish to hide in, so they tend to be a bit shy in the middle of the day during the summer months.
Grantsville has some very large Browns and Rainbows that feed heavily on carp minnows when they are still small enough to be targeted. This means that summer through late fall you can catch some monster trout by fishing with carp minnows. You can catch the minnows right at the reservoir using dipnets or cast nets.