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