Red Willow Dam


Red Willow Dam, located on Red Willow Creek about 10 miles northwest of McCook, is an earthfill embankment with a structural height of 126 feet that forms a reservoir of 86,630 acre-feet. An ungated concrete spillway is located in the right abutment. An outlet works through the base of the dam provides for river and irrigation releases for downstream diversions. The reservoir behind this dam is Hugh Butler Lake.

Public Information Portal Red Willow Dam/Hugh Butler Lake, Neb.

Lying beneath the dam and abutments is the Ash Hollow member of the Ogallala Formation (To), a Mio-Pliocene nonmarine deposit of variably cemented sand, silt, clay, and gravel.  The Ogallala is a major aquifer in the area.

Overlying the Ogallala at the abutments are discontinuous beds of Pleistocene Crete Sand (Qcf), which fill shallow paleochannels on top of the Ogallala Formation.  (Though detected only during investigations of the left abutment, it is assumed that the Crete Sand is intermittently present at both abutments.)  Pleistocene Loveland and Peorian loess (Ql), consisting of silt and fine sand, rest on top of Crete Formation and form the upper part of the abutments.

The foundation of the dam consists of approximately 40 feet of alluvium (Qu and Qal) deposited in the old Red Willow Creek channel on top of the Ogallala Formation.  Beneath the Ogallala Formation, at a depth of approximately 120 to 130 feet, is Pierre Shale.  A considerable portion of the alluvium consists of saturated, well-sorted sand which may be potentially liquefiable.  The upper alluvial zone (Qu) is described as alluvial silt and has much lower horizontal and vertical permeability than the alluvial silty sand (Qal) zone that lies below it.

The spillway and outlet works, located in the right abutment of the dam, are both founded on the Ogallala Formation.  Excavation for the outlet works was primarily within the Ogallala Formation, whereas excavation for the spillway was primarily through loessial materials.

There are no known faults in formations exposed in the area, nor are there any landslides of significant size known to exist in the area around the reservoir.

RegionFacilities in Great Plains | Great Plains Home Page
ProjectFrench-Cambridge (PSMBP)
Dam Type
ReservoirHugh Butler Lake
WatercourseRed Willow Creek
Location11 mi N of McCook
Original Construction1960-1962
Modified Construction
National ID NumberNE01076
Hydrologic Unit Code

Structural Height126.0 ft
Hydraulic Height (Normal Operating Depth at Dam)123.0 ft
Top Parapet (Elevation)
Spillway Crest Elevation2604.9 ft
Crest Elevation2634.0 ft
Crest Length3159.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials
Streambed at Dam Axis2511.0 ft
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)2581.8 ft
Top of Inactive Conservation Pool (Elevation)2558.0 ft
Top of Dead Storage Pool (Elevation)2552.0 ft

Hydraulics & Hydrology
Total Water Storage at Elevation
Maximum Water Surface Elevation
Normal Water Surface Elevation2628.0 ft
Spillway Type
Auxiliary Spillway
Spillway Capacity at Elevation4910 cfs at 2627.8 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation1150 cfs at 2604.9 ft
Diversion Capacity at Elevation
Drainage Area
Hydrometeorological Report (HMR)HMR x
Probable Maximum Flood (PMF) Report

Contact Information
TitleArea Office Manager
OrganizationNebraska-Kansas Area Office
Address1706 West Third
CityMcCook, NE 69001
Phone (Office)308-345-4400
Phone (Fax)308-345-6470
TitleArea Office Manager
OrganizationNebraska-Kansas Area Office
Address1706 West Third
CityMcCook, NE 69001
Phone (Office)308-345-4400
Phone (Fax)308-345-6470

Last updated: Apr 08, 2013