Rattlesnake Dam

Rattlesnake Dam lies in an erosional gap cut by Rattlesnake Creek.  This creek drains a synclinal depression cutting into the Precambrian core.  Compressional stresses and mountain uplift have developed folding and minor faulting at the site.  Schistose foliations within exposed rock strikes generally east-west across the regional mountain axis.  Exposed rock at the site consists of Precambrian schist, gneiss, and granite-gneiss.  The schist is hard, micaceous gray material  that is soft and decomposed at the surface.  The gneiss and granite-gneiss are hard, grey material, sometimes altered and broken.   The dam was built on mostly schistose-gneiss of the Precambrian Idaho Springs Formation.  This rock is generally grey to light gray, medium to fine grained, fractured, and thinly to very thinly foliated.  Near the ground surface the rock is weathered and decomposed.  Decomposed rock is soft, while harder sound rock occurs at increased depth.  Weathering and decomposition may be on the order of several tens of feet.   Overlying the bedrock are alluvium and colluvium associated with the present day Rattlesnake Creek erosion.  Average depth of these materials is about ten feet.  These materials transition in depth and gradation towards outcrops on the surrounding hills.  Alluvium generally consists of sands and gravels with a few cobbles and boulders residing in the stream bed area.  Colluvium consists of similar materials, but more towards the cobbles and boulders gradation, that are wasting downslope from the hill sides.

RegionFacilities in Great Plains | Great Plains Home Page
ProjectColorado-Big thompson
Dam Type
WatercourseRattlesnake Creek
Net Generation
Original Construction1951-1952
Modified Construction
National ID NumberCO01663
Hydrologic Unit Code

Structural Height130.0 ft
Hydraulic Height (Normal Operating Depth at Dam)100.0 ft
Top Parapet (Elevation)
Spillway Crest Elevation6580.0 ft
Crest Elevation6595.0 ft
Crest Length1951.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials
Streambed at Dam Axis6480.0 ft
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)6580.0 ft
Top of Inactive Conservation Pool (Elevation)6556.0 ft
Top of Dead Storage Pool (Elevation)6550.0 ft

Hydraulics & Hydrology
Total Water Storage at Elevation
Maximum Water Surface Elevation
Normal Water Surface Elevation6580.0 ft
Spillway Type
Auxiliary SpillwayNo
Spillway Capacity at Elevation10400 cfs at 6589.0 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation23.0 cfs at 6589.0 ft
Diversion Capacity at Elevation
Drainage Area3.5 sq mi
Hydrometeorological Report (HMR)HMR 55A
Probable Maximum Flood (PMF) Report

Contact Information
TitleArea Office Manager
OrganizationEastern Colorado Area Office
Address11056 W. County Rd 18E
CityLoveland, CO 80537-9711
Phone (Fax)970 663-3212
Phone (Office)970 667-4410
TitleArea Office Manager
OrganizationEastern Colorado Area Office
Address11056 W. County Rd 18E
CityLoveland, CO 80537-9711
Phone (Fax)970 663-3212
Phone (Office)970 667-4410

Last updated: Apr 02, 2013