Pertinent Data
| General | ||
| Location: | ||
| State County River River Mile |
Washington Franklin and Walla Walla Snake 41.6 | |
| River miles upstream from Ice Harbor Dam | 31.9 | |
| Owner | U.S. Army Corps of Engineers, Walla Walla District | |
| Authorized Purpose | Power generation and inland navigation | |
| Other Uses | Fishery and recreation | |
| Type of Project | Run-of-river | |
| Real Estate: | ||
| Fee acquisition land, acres | 7,519 | |
| Reservoir | ||
| Name | Lake Herbert G. West | |
| Elevations (Feet Mean Sea Level): | ||
| Maximum at dam for spillway design flood Normal operating range gauged at dam Length, miles |
548.3 537 to 540 28.7 | |
| Average width, miles | 0.4 | |
| Maximum width, miles | 0.8 | |
| Surface area at elevation 540 (low flow-flat pool), acres | 6,590 | |
| Storage between elevation 537 and 540 (acre feet) | 20,000 | |
| Dam (General) | ||
| Powerhouse, overall length | 656 | |
| Spillway, total length | 498 | |
| Navigation lock, overall width | 186 | |
| Concrete non-overflow sections: | ||
| Navigation lock to spillway (length, feet) Spillway to powerhouse (length, feet) Powerhouse to north shore embankment (length, feet) Earth embankment, north shore (length, feet) Earth embankment, south shore (length, feet) |
143 37 228 968 1,075 | |
| Total length of dam (feet) | 3,791 | |
| Maximum height of concrete sections (foundations deck, feet) | 256.7 | |
| Maximum height of abutment section (North Shore foundation to top) | 154.8 | |
| Deck elevation | 553 feet msl | |
| Top of abutment elevation | 558 feet msl | |
| Spillway | ||
| Type | Ogee, concrete, gravity, gate controlled | |
| Maximum width at base, elevation 392 feet msl (feet) | 152 | |
| Maximum height, foundation to deck (feet) | 152 | |
| Number of bays | 8 | |
| Overall length, feet (abutment centerlines) | 512 | |
| Clear length, feet | 400 | |
| Crest elevation, feet msl | 483 | |
| Gate seal elevation, feet msl | 481.44 | |
| Top of gate in closed position, elevation | 542 | |
| Deck elevation, feet msl | 553 | |
| Gate lip elevation at maximum opening, feet msl | 535 | |
| Control gates: | ||
| Type Size Method of operation |
Tainter 50'W x 60'H Individual electric hoists, remote controlled | |
| Maintenance closure for spillway bays | Stoplogs | |
| Spillway design flood: | ||
| Peak discharge Pool elevation, feet msl Tailwater elevation, feet msl Gross head, feet | 850,000 cfs 548.3 465.1 83.2 |
|
| Maximum flood at normal pool, elevation 540 | ||
| Discharge Tailwater elevation, feet, msl |
676,000 cfs 460.5 | |
| Stilling basin: | ||
| Type Width, perpendicular to flow, feet Length, parallel to flow, feet Floor elevation, feet msl Height of continuous end sill, feet |
Horizontal apron 498 180 392 13 | |
| Powerhouse | ||
| Number of generating units | 6 | |
| Spacing, feet: | ||
| Units 1 through 5 Unit 6 Erection and service bay |
90 96 110 | |
| Turbines: | ||
| Type Runner diameter, inches Revolutions per minute Rating horsepower |
Kaplan, 6-blade 312 90 212,400 | |
| 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 | ||
| Type | Single lift | |
| Net clear length, lock chamber, feet | 650 | |
| Net clear width, lock chamber, feet | 86 | |
| Minimum water depth over stills, feet | 15 | |
| Upstream gate: | ||
| Type Height, feet | Vertical lift 22 | |
| Downstream gate: | ||
| Type Height, feet | Vertical lift 84.08 | |
| Maximum operating lock lift, feet | 103.00 | |
| Normal fill time | 11.3 minutes | |
| Normal emptying time | 13.3 minutes | |
| Fish Facilities | ||
| Number of fish ladders | 2 | |
| Slope | 1V on 10H | |
| Number of weirs (including orifice-control section) | 103 | |
| Overflow weirs: | ||
| Number Height Orifice size |
97 6 feet 18 x 18 inches | |
| Exit of ladders, invert elevation, feet msl | 530.5 | |
| Entrance of ladder, invert elevation, feet msl | 429 | |
| Normal fishway flow, forebay to each ladder, cfs | 74 | |
| Ladder clear width, feet | 16 | |
| Pumps for fish attraction water: | ||
| Number Type Capacity, cfs Forebay water required for each turbine, cfs | 3 turbine 835 65 | |
| Fishway entrances: | ||
| North shore South shore Non-overflow |
2 3 3 | |
| Powerhouse collection system: | ||
| Number of orifice entrances Length of channel, feet Width of channel, feet | 10 600 17.5 | |
| Fingerling bypass system: | ||
| Collection system openings per gate slot Size of collector pipes, inches Forebay water required (per powerhouse unit), cfs |
1 6 2.4 | |
| Hydrologic Data (Based on streamflow data for the Snake River near Clarkston, Washington) | ||
| Drainage area, square miles | 103,200 | |
| Period of record | Oct 1915 to Sep 1972 (Discontinued in Dec 1972) | |
| Discharges in cubic feet per second: | ||
| Instantaneous maximum of record, 29 May 1948 Instantaneous minimum of record, 2 Sep 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 | |