Congratulations to Just Hike for the First to Find!
Stewart Mountain Dam was built in the late 1920s to form Saguaro Lake. The impounded Salt River is used for hydroelectric generation and irrigation. Just below the dam on river right is the Saguaro Lake Ranch, created from the work camp that was built to facilitate construction of the dam. Lake levels vary both seasonally and daily.
It's quite possible that you many encounter horses on this trail, especially in the winter. Horses have the right of way. Step off the trail and stand quietly while they pass. The usual cautions regarding geocaching in the desert apply. Be sure to carry plenty of water for this 1.5 mile R/T hike. The trail is unmarked and rough in places, but there is no need for cross-country bushwacking. The trail is always the better option. Expect flora and fauna that want to poke, scratch, bite, and could be poison. Closed toed shoes and long pants are highly recommended for this quest.
I've provided you with coordinates for the start of the trail. Follow the normally dry wash downhill to the second provided coordinate where the trail leaves the wash at approximate right angles. From that point, you're on your own to explore the saguaros, palo verdes, pencil cactus, and other wonders of our local desert. All stages except the final are micros. PLEASE, NO TRADES.