General State - Washington
County - Franklin and Walla Walla
River - Snake
River Mile - 9.7
Drainage area above Ice Harbor Dam - 109,000 square miles
Owner - U.S. Army Corps of Engineers, Walla Walla District
Authorized Purposes - Inland Navigation and Power Generation
Other Uses - Fishery and recreation
Type of Project - Run-of-river
Real Estate:
Fee acquisition land above pool elevation 440 - 7,830 acres
Reservoir
Name - Sacajawea
Elevations (Feet Mean Sea Level)
Maximum at dam for spillway design flood - 446.4
Normal operating range gauged at dam - 437 to 440
Length - 31.9 miles
Average width - 0.4 miles
Maximum width - 1.0 miles
Surface area at elevation 440 (low flow-flat pool) - 8,375 acres
Storage between elevation 437 and 440 - 24,900 acre feet
Dam (General)
Powerhouse, overall length - 671 feet
Spillway, total length - 590 feet
Navigation lock, overall width - 173 feet
Concrete non-overflow sections:
Navigation lock to spillway (length) - 154 feet
Spillway to powerhouse (length) - 40 feet
Powerhouse to south shore embankment (length) - 560 feet
Earth embankment, north shore (length) - 624 feet
Total length of dam - 2,822 feet
Maximum height of concrete sections (foundations deck) - 213 feet
Maximum height of abutment section (north shore foundation to top) - 123 feet
Deck elevation - 453 feet msl
Spillway
Type - Ogee, concrete, gravity, gate controlled
Maximum width at base, elevation 392 feet msl - 139 feet
Maximum height, foundation to deck - 141 feet
Number of bays 10
Overall length, (abutment centerlines) 590 feet
Clear length - 500 feet
Crest elevation - 391 feet above sea level
Gate seal elevation - 389.07 feet above sea level
Top of gate in closed position - 442 feet above sea level
Deck elevation - 453 feet above sea level
Gate lip elevation at maximum opening - 436 above sea level
Control gates:
Type - Tainter
Size - 50'W x 52.9'H
Method of operation - individual electric hoists, remote and manually controlled
Maintenance closure for spillway bays - Stoplogs
Spillway design flood:
Peak discharge - 850,000 cfs
Pool elevation - 446.4 feet above sea level
Tailwater elevation - 374 feet above sea level
Gross head - 72.4 feet
Maximum flood at normal pool elevation 440
Discharge - 685,000 cfs
Tailwater elevation - 370.5 feet above sea level
Gross head - 72.4 feet above sea level
Stilling Basin
Type - Horizontal apron
Width, perpendicular to flow - 590 feet
Length, parallel to flow - 168 feet
Floor elevation - 304 feet above sea level
Height of continuous end sill - 12 feet
Powerhouse
Number of generating units 6
Spacing:
Units 1 through 5 - 90 feet
Unit 6 - 96 feet
Erection and service bay 110
Turbines:
Type - Kaplan, 6-blade
Runner diameter:
Units 1 through 3 - 280 inches
Units 4 through 6 - 300 inches
Revolutions per minute:
Units 1 through 3 - 90
Units 4 through 6 - 87.5
Generators:
Rating (nameplates):
Units 1 through 3 - 90,000 kilowatts
Units 4 through 6 - 111,000 kilowatts
Power factor - 0.95
Kilovolt ampere rating:
Units 1 through 3 - 95,00
Units 4 through 6 - 117,000
Units installed complete initially - 3
Skeleton units provided initially - 3
Total units now installed - 6
Plant rated capacity - 603,000 kilowatts
Crane capacities:
Intake (joint use with spillway) - 85 tons
Bridge - 500 tons
Draft tube gantry - 35 tons
Navigation Lock and Channels
Type - Single lift
Net clear length, lock chamber - 675 feet
Net clear width, lock chamber - 86 feet
Minimum water depth over lower sill - 16 feet
Upstream gate:
Type - Radial
Height - 25 feet
Downstream gate:
Type - Vertical Lift
Height - 91 feet
Maximum operating lock lift - 105 feet
Length of guidewalls (from face of gate):
Upstream (floating) - 746 feet
Downstream - 696 feet
Normal fill time - 11 minutes
Normal emptying time - 14 minutes
Fish Facilities
Number of fish ladders - 2
Slope:
North Shore - 1V on 10H
South Shore - 1V on 16H
Number of weirs (including orifice-control section) - 103
Overflow weirs:
Number - 97
Height - 6 feet
Orifice size:
North Shore - 18 x 18 inches
South Shore - 21 x 23 inches
Exit of ladders, invert elevation - 431 feet above sea level
Entrance of ladder, invert elevation - 332 feet above sea level
Normal fishway flow, forebay to each ladder:
North Shore - 74 cfs
South Shore - 142 cfs
Ladder, clear width:
North Shore - 16 feet
South Shore - 24 feet
Pumps for fish attraction water:
Number:
North Shore - 3
South Shore - 8
Type - Turbine
Discharge:
North Shore - 250 cfs
South Shore - 300 cfs
Fishway entrances:
North shore - 2
South shore - 3
Non-overflow - 3
Powerhouse collection system:
Number of orifice entrances - 12
Length of channel - 661 feet
Width of channel - 17.5 feet
Downstream Migrants Bypass System:
Ice-and-trash sluiceway - 1
Hydraulic capacity 2700 cfs
Hydrologic Data
(Based on streamflow data for the Snake River near Clarkston, Washington)
Drainage area - 103,200 square miles
Period of record - Oct 1915 to Sept 1972 (Discontinued in Dec 1972)
Discharges in cubic feet per second:
Instantaneous maximum of record, 29 May 1948 - 369,000
Instantaneous minimum of record, 2 Sep 1958 - 6,660
Average annual flow - 48,840
Average annual mean daily peak flow - 188,300
Extreme outside period of record:
Flood of June 1894 - 409,000
Flood of June 1894 controlled by existing projects - 295000
Standard project flood (controlled by existing projects):
Snake River below Clearwater River - 420,000
Snake River above Clearwater River - 295,000
Clearwater River above Snake River - 150,000
Spillway design flood 850,000