Pertinent Data
General | ||
Location: | ||
State County River River Mile Township Range Section Latitude Longitude |
Washington Garfield and Whitman Snake 107.5 14 N 43 E 32 46° 39' 37" 117° 25' 37" | |
River miles from mouth of Snake River | 107.5 | |
River miles upstream from Little Goose Dam | 37.2 | |
Owner | U.S. Army Corps of Engineers, Walla Walla District | |
Authorized Purpose | Power generation and inland navigation | |
Other Uses | Flood control (maintain levee freeboard at Lewiston), fishery, and recreation | |
Type of Project | Run-of-river | |
Real Estate: | ||
Fee acquisition land above pool elevation 738, acres | 9,224 |
Reservoir | ||
Name | Lower Granite Lake1 | |
Elevations (Feet Mean Sea Level): | ||
Maximum at dam for spillway design flood Normal operating range at confluence gage (RM 139.5) Minimum at dam for standard project flood |
746.5 738 to 733 724 | |
Length, miles: | ||
Snake River (to Asotin damsite, RM 146.8) Clearwater River |
39.3 4.6 | |
Length of shoreline, miles | 91 | |
Average width, miles | 0.3 | |
Maximum width, miles | 0.6 | |
Surface area at elevation 738 (low flow, flat pool), acres | 8,900 | |
Storage below flat pool elevation 738, acre-feet | 483,800 | |
Storage below flat pool elevation 733, acre-feet | 440,200 | |
Storage between elevation 733 and 738 | 43,600 | |
Height normal high pool to tailwater elevation 638 (low flow, 30,000 cfs or less), feet | 100 |
Levees | ||
Top width, feet | 12 | |
Slopes, waterside and landside | 1V on 2H | |
Materials | Gravel and earth fill with impervious core | |
Top elevation | 5 feet above backwater profile for standard project flood | |
Embankment length, miles: | ||
Lewiston | 8.6 | |
Installed pumping capacity, cfs: | ||
Lewiston levees | 450.4 |
Dam (General) | ||
Axis (Lambert) | N 32° 00'E | |
Length and Widths, feet: | ||
Dam total length at crest North abutment embankment South non-overflow monoliths Spillway overall length Spillway to powerhouse non-overflow Powerhouse overall length Spillway to navigation lock non-overflow Navigation lock overall width at foundation Navigation lock overall width at deck |
3,200 1,435 32.2 512 43.4 656 43.4 304 186 | |
Concrete Heights, feet: | ||
Maximum overall concrete height (powerhouse sump deck to deck) Maximum non-overflow monoliths height:
|
254 151 166 181 191 | |
Deck elevations, feet msl: | ||
Intake, spillway bridge, non-overflow sections, and upstream end of
navigation lock Downstream end of navigation lock South shore fish ladder Tailrace and fishwater intake North abutment embankment |
751 746 656 656 756 |
Spillway | ||
Number of Bays | 8 | |
Overall length, feet (abutment centerlines) | 512 | |
Deck elevation, feet msl | 751 | |
Ogee crest elevation, feet msl | 681 | |
Flip lip elevation | 630 | |
Control gates: | ||
Type Size | Tainter 50'W x 60'H | |
Gantry crane (joint use with powerhouse) capacity, tons | 100 | |
Stilling basin length, feet | 188 | |
Stilling basin elevation, feet msl | 580 | |
Maximum design capacity, cfs | 850,000 |
Powerhouse | ||
Length overall, feet | 656 | |
Spacing, feet: | ||
Units 1 through 5 Unit 6 Erection and service bay |
90 96 110 | |
Width overall, transverse section, feet | 243.17 | |
Intake deck elevation, feet msl | 751 | |
Tailrace deck elevation, feet msl | 656 | |
Maximum height (draft tube invert to intake deck), feet | 228 | |
Turbines: | ||
Type Runner diameter, inches Revolutions per minute Rating horsepower Distributor centerline elevation |
Kaplan, 6-blade 312 90 212,400 599 | |
Generators: | ||
Rating (nameplates), kilowatts Power factor Kilovolt ampere rating |
135,000 0.95 142,100 | |
Units installed complete initially | 3 | |
Skeleton units provided initially | 3 | |
Total units now installed | 6 | |
Plant capacity, nameplate rating, kilowatts | 810,000 | |
Crane capacities, tons: | ||
Intake (joint use with spillway) Bridge Draft tube gantry |
100 600 50 |
Navigation Lock and Channels | ||
Net clear length, lock chamber, feet | 674 | |
Net clear width, lock chamber, feet | 86 | |
Upstream gate: | ||
Type Height, feet | Submersible tainter 23 | |
Downstream gate: | ||
Type Height, feet | Miter 122 | |
Operating water surface elevations in chamber | 633 to 738 | |
Maximum operating lock lift, feet | 105 | |
Lift, feet (riverflow 300,000 cfs, practical navigation limit) | 88.2 | |
Length of guidewalls (from face of gate), feet: | ||
Upstream (floating) Downstream | 750 700 | |
Downstream approach channel: | ||
Width, feet Bottom elevation | 250 617 | |
Minimum tailwater elevation | 633.0 | |
Lower lock sill elevation, feet | 618.0 | |
Upper lock sill elevation, feet | 718.0 | |
Maximum depth over sills, feet | 20.0 | |
Minimum depth over sills, feet | 15.0 |
Abutment Embankment | ||
Embankment elevation | 756 | |
Embankment top width, feet | 45 | |
Material | Gravel fill with rock facing, impervious silt core | |
Upstream Downstream | Combination sand and gravel
filters Gravel and sand filters | |
Slope, upstream | 1V on 2H | |
Slope, downstream | 1V on 2H |
Fish Facilities 2 | ||
Upstream migrants fish ladder: | ||
Number of fish ladders Slope
Ladder clear width, feet Design capacity, cfs | 1 1V on 10H 1 V on 32H 20 75 | |
Exit Channel: | ||
Location Top of trashrack Invert Width, feet |
Between weir 737 and pool in non-overflow section El. 732 El 727 6 | |
Alternative exit channel (pool elevation below 727): | ||
Exit pipe to reservoir | 18-inch-diameter full plastic
pipe down to El. 718, and a half-round plastic pipe down to El. 710 | |
Operating elevations: | ||
Design range: | ||
Pool elevations Tailwater elevations Riverflow |
733 to 738 633 to 642 0 to 225,000 cfs | |
Maximum operating range: | ||
Pool elevations Tailwater elevations Riverflow |
732 to 739 633 to 645.4 0 to 340,000 cfs | |
Adult fish trap and handling facility | 1 | |
Pumps for fishway system attraction water: | ||
Number Capacity, cfs | 3 3,150 | |
Downstream migrants bypass system: | ||
Design pool range Design capacity, cfs Extended-length Submerged Bar Screens Vertical barrier fish screens Orifices from bulkhead and fish screen slots:
Fingerling transportation pipe |
733 to 738 200 to 250 18 18 36, 36 10, 12 1 1 | |
Fingerling holding and sampling facility | 1 | |
Fingerling transportation facilities: | ||
Truck loading facility Barge loading facility |
1 1 |
Hydrologic Data (Based on streamflow data for the Snake River near Clarkston, Washington) | ||
Drainage area, square miles | 103,200 | |
Period of Record | October 1915 to September 1972 (Discontinued in December 1972) | |
Discharges, cfs: | ||
Instantaneous maximum of record, 29 May 1948 Instantaneous minimum of record, 2 September 1958 Average annual flow Average annual mean daily peak flow |
369,000 6,660 50,300 188,300 | |
Extreme outside period of record: | ||
Flood of June 1894 Flood of June 1894, controlled by existing projects | 409,000 295,000 | |
Standard project flood, controlled by existing projects: | ||
Snake River below Clearwater River Snake River above Clearwater River Clearwater River above Snake River |
420,000 295,000 150,000 | |
Spillway design flood | 850,000 |