Location
Upper Stillwater Reservoir is located in Duchesne County, Utah and is part of the Uinta Moutain range. There are two paths that most people take to get here. The first is the Moon Lake turn off from the city of Duchesne. You head north on UT-87 for six miles and then turn left or west onto UT-35 and go 3.5 miles until you see the turnoff to Rock Creek Road on the right or north. You will follow Rock Creek Road to the dam which is about 29.5 miles. The second most popular route is to take UT-135 from near Hannah Utah. This is a dirt road and is not nearly as nice as the main route described above.
Fish Species
Brook Trout. Many sites claim that there are also Brown Trout and Rainbow Trout stocked in the reservoir. Going back to 2002 the DWR doesn't report stocking any fish in the reservoir. I've read a few reports of people catching Brook Trout but not any other fish. So until somoeone can prove otherwise we will say there are only Brook Trout in this water.
Regulations
Every few years the reservoir will fill to capacity and flow over the dam. Because of this there is special regulations for watercraft. When the water level is at or above the measurement of 8,157 ft elevation you are not allowed to launch a watercraft. You can see in the two pictures below where the number is painted on the boat ramp and the dam. Due to construction to secure falling rocks (source) the boat ramp is too skinny to back a boat down. So per regulation you must carry the watercraft over the gate. You can see the gate in the above picture on the right. You can also see the newly installed nets to stop falling rocks.
The Dam
The Upper Stillwater Reservoir Dam is over 600 feet wide and over 200 feet tall. This makes the damn taller than Niagra Falls (source). Every few years the water will fill to capacity creating an amazing gigantic waterfall. If you look on youtube for Upper Stillwater Reservoir Dam Waterfall you will see some pretty epic videos.
Tributaries
Rock Creek flows out of the resevoir and runs through the canyon below. This area provides a lot of areas for fishing, camping, and hiking.
Nearby Areas to Fish
Rock Creek River, Audry Lake, Bear lake, Cabin Creek, Cabin Lake, Docs Lake. It's an equal distance to the Grandaddy Lakes and Kidney Lake.