Stewart Mountain Dam, Hydroelectric dam in Maricopa County, United States.

Stewart Mountain Dam is a concrete arch dam that spans across the Salt River, creating Saguaro Lake to the northeast of Phoenix. The structure harnesses water flow to generate electricity for the surrounding region.

Built between 1928 and 1930, Stewart Mountain Dam was the last of three dams the Salt River Valley Water Users' Association added below Roosevelt Dam, after Mormon Flat (1923-1925) and Horse Mesa (1924-1927), to use the Salt River's water for power as well as irrigation. From 1988 to 1992 the Bureau of Reclamation added a second spillway on the right side and reinforced the wall with 84 steel anchors drilled into the rock beneath. It was listed on the National Register of Historic Places in 2017.

The dam takes its name from the Old Stewart Ranch that once stood nearby. Its 13,000 kW unit is run mainly in summer, when demand for power peaks. The 1927 workers' camp below the dam became the Saguaro Lake Guest Ranch.

The dam stands 41 miles northeast of Phoenix, with Mormon Flat Dam about 16 km upstream and the Granite Reef diversion weir roughly 30 km downstream. The powerhouse sits at the foot of the dam on the right side, below the 63 m crest. The structure is a working utility facility owned by SRP, so viewing is from outside rather than inside.

Construction workers lived in a temporary camp that was later transformed into a guest ranch after the dam was completed. This repurposing shows how project infrastructure shifted to serve recreational use.