Whitlow Ranch Dam

Background

Whitlow Ranch Dam is an ungated flood control structure located on Queen Creek in Pinal County, Arizona. The dam is located (see: Map 1 & Map 2) about 50 miles southeast of the City of Phoenix and about 7 miles northeast of the town of Florence Junction.  The drainage area tributary to Whitlow Ranch Dam comprises about143 square miles. This upstream area is bordered on the east by the Pinal Mountains and includes the town of Superior.  The dam was built in 1960 to provide flood protection to farmland and developed areas including the communities of Chandler, Gilbert, Queen Creek, and Florence Junction and portions of Williams Air Force Base.  The outlet works does not include any mechanical equipment that will permit significant adjustment to large outflows.   Essentially the project operates for flood control automatically.  Included in the project is a slide gate and a outlet-and-diversion structure designed to divert water and satisfy local water rights.  Local interests, who have acquired these water rights, operate the slide gate to divert outflow from the reservoir into a irrigation ditch.  Diverted flows have an negligible impact on outflows from the dam during a flood event. 

Continuous low flows (less than 10 cfs) pass through Whitlow Ranch Dam's outlet works.   Large discharges occur following heavy rains in the area above the dam.   Outflow usually percolates into the alluvial plain below the dam and rarely travels more than a few miles downstream.  Only flows from very large and infrequent storms will drain into the Gila River at a location about 40 miles downstream from the dam.

Photographs of Whitlow Ranch Dam

Physical Data

Embankment
Type Earthfilll
Year Built 1960
Crest Elevation 2,199 feet NGVD 670 meters NGVD
Invert elevation 2,056 feet NGVD 627 meters NGVD
Height above original streambed 149 feet 45 meters
Crest Length 837 feet 255 meters
Top Width 20 feet 6.1 meters
PMF Freeboard 5 feet 1.5 meters
Spillway
Type Detached, broadcrested
Crest Elevation 2,166 feet NGVD 660 meters NGVD
Crest Length 355 feet 108 meters
Elevation of Maximum Water Surface 2,194  feet NGVD 669 meters NGVD
Discharge at Maximum Water Surface 147,000 cfs 4,163 cms
Outlet
Invert Elevation 2,056 NGVD 627 meters
Diameter 5.5 feet 1.7 meters
Length 700 feet 213 meters
Capacity at Spillway Crest 1,007 cfs 29 cms
Surface Area & Storage Capacity
Area at Spillway Crest 822 acres 3,326,516 sm
Area at Top of Dam 1,335 acres 5,402,553 sm
Storage Capacity at Spillway Crest 35,593 acre-feet 43.9 MCM
Storage at Spillway Design Surcharge Level 64,556 acre-feet 79.6 MCM
Storage Capacity at Top of Dam 71,032 acre-feet 87.6 MCM
Sedimentation Allocation 6,700 acre-feet 8.3 MCM
Reservoir Design Flood
Duration of Inflow 21 hours 21 hours
Total Volume 30,000 acre-feet 37.0 MCM
Peak Inflow 110,000 cfs 3,115 cms
Peak Outflow 1,004 cfs 28 cms
Spillway Design Flood
Duration of Inflow 19 hours 19 hours
Total Volume 74,000 acre-feet 91.3 MCM
Peak Inflow 230,000 cfs 6,513 cms
Peak Outflow 147,000 cfs 4,163 cms
Notes:
NGVD = National Geodetic Vertical Datum of 1929.
MCM = million cubic meters
cfs = cubic feet per second
cms = cubic meters per second
sm = square meters

 

View Current Whitlow Ranch Dam Gage Data

Whitlow Ranch Dam Flood Inundation Maps

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Last Updated on October 26, 1998 by Greg Peacock