Fort Cobb Dam

The foundation materials consist of as much as 117 feet of alluvium over bedrock in the flood plain, and relatively thin deposits of residual and slope-wash soils over bedrock on the abutments. The bedrock is sandstone and siltstone of the Rush Springs Formation. Ground surface and bedrock surface profiles are shown on enclosure 1. Also shown on enclosure 1 are the profiles of the bottoms of the down-stream foundation trench and the upstream cutoff trench. These trenches were excavated through shallow weak layers in the flood plan alluvium from stations 49+00 to 64+00 to aid embankment stability     The upstream cutoff trench was also intended to reduce foundation seepage.On the abutments, the upstream cutoff trench was excavated to sound bed-rock up to the normal water surface elevation at approximately station 30+00 and station 80+00     The downstream foundation trench was back-filled with a drainage blanket followed by impervious, compacted Zone 1 fill. The upstream cutoff trench was backfilled with impervious, compacted Zone 1 fill only.

The spillway and outlet works are located on the left and right abutments, respectively. Both structures are founded entirely on sound siltstone and sandstone bedrock.

RegionFacilities in Great Plains | Great Plains Home Page
ProjectWashita Basin
Dam Type
ReservoirFort Cobb
WatercourseCobb Creek
Original Construction1958-1959
Modified Construction
National ID NumberOK02502
Hydrologic Unit Code

Structural Height122.0 ft
Hydraulic Height (Normal Operating Depth at Dam)95.4 ft
Top Parapet (Elevation)
Spillway Crest Elevation1354.8 ft
Crest Elevation1380.0 ft
Crest Length9900.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials
Streambed at Dam Axis1279.0 ft
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)1342.0 ft
Top of Inactive Conservation Pool (Elevation)
Top of Dead Storage Pool (Elevation)1300.0 ft

Hydraulics & Hydrology
Total Water Storage at Elevation
Maximum Water Surface Elevation
Normal Water Surface Elevation1342.0 ft
Spillway Type
Auxiliary Spillway1374.4
Spillway Capacity at Elevation0.0 cfs at 1374.4 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation
Diversion Capacity at Elevation
Drainage Area317.0 sq mi
Hydrometeorological Report (HMR)HMR 51 & 52
Probable Maximum Flood (PMF) Report

Contact Information
TitleArea Office Manager
OrganizationOklahoma-Texas Area Office
Address5316 HWY 290 W, Suite 510
CityAustin, TX 78735-8931
Phone (Office)512 899-4150
Phone (FAX)512 899-4179
OrganizationFort Cobb Reservoir Conservancy District
AddressPO Box 40
CityAnadarko, OK 73005
Phone (Office)580 247-3782

Last updated: Mar 29, 2013