Stewart Mountain Dam


On the Salt River 41 miles northeast of Phoenix, Stewart Mountain Dam created Saguaro Lake, a 69,765 acre-foot capacity reservoir. The dam is a concrete thin-arch structure, 207 feet high, with gravity abutments. When built by the Salt River Valley Water Users' Association from 1928-1930, the dam included an open, super-elevated channel spillway equipped with radial gates.

The spillway was modified by Reclamation in 1936. The work consisted of building a concrete-lined spillway discharge channel, 450 feet long by 265 feet wide, below the existing ogee spillway; reconditioning the hoisting equipment for the radial gates; and installing individual gate operating motors and two 10-kilovolt-ampere gasoline-engine driven generators.

From 1988 to 1992, the dam was again modified by Reclamation, to meet concerns about its stability in a probable maximum flood or maximum credible earthquake. To address PMF concerns, a new spillway was constructed on the dam`s right abutment to increase its ability to safely release flood waters. As part of earthquake protection measures, a new concrete overlay was placed over areas on the right and left abutments to improve the dam`s stability. The existing power penstock and river outlet works were also replaced, the road on the top of the dam was raised and widened, and the existing left spillway and spillway wall was modified. In addition, drainage holes were drilled at selected locations in the dam`s foundation to help relieve hydraulic uplift pressures, and some areas of the foundation were grouted to help reduce seepage. Finally, 84 steel cables were installed through the dam and into its foundation to strengthen it.


RegionFacilities in Lower Colorado | Lower Colorado Home Page
ProjectSalt River
Dam TypeConcrete thin arch
ReservoirSaguaro Lake
WatercourseSalt River
LocationOn the Salt River, 41 miles northeast of Phoenix, Arizona
Original Construction1928-1930
Modified Construction1936, 1988-1992
National ID NumberAZ10318
Hydrologic Unit Code

Structural Height207 ft
Hydraulic Height (Normal Operating Depth at Dam)116 ft
Top Parapet (Elevation)
Spillway Crest Elevation1529 ft
Crest Elevation1533 ft
Crest Length1,260 ft
Crest Width8 ft
Base Width33 ft
Volume of Dam Construction Materials120,000 cu-yds
Streambed at Dam Axis
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)
Top of Inactive Conservation Pool (Elevation)
Top of Dead Storage Pool (Elevation)

Hydraulics & Hydrology
Total Water Storage at Elevation73,613 acre-ft at 1532
Maximum Water Surface Elevation1532 ft
Normal Water Surface Elevation
Spillway Type Concrete weir and concrete lined open channel
Spillway Capacity at Elevation115,000 cfs at 1532
Auxiliary Spillway
Auxiliary Spillway Capacity at Elevation87,000 cfs at 1532 ft
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation1,800 cfs at 1510 ft
Diversion Capacity at Elevation
Drainage Area6,330 sq mi
Hydrometeorological Report (HMR)HMR 49
Probable Maximum Flood (PMF) Report1981 Local Summer Flood

Contact Information
TitleArea Office Manager
OrganizationPhoenix Area Office
Address6150 West Thunderbird Road
CityGlendale, AZ 85306-6200
Phone (Fax)623 773-6480
Phone (Office)623 773-6200
OrganizationArea Office Manager
AddressPhoenix Area Office
CityPhoenix, AZ 85306-6200
Phone (Office)623 773-6200

Last updated: Jun 29, 2009