Dworshak Dam and Reservoir

Pertinent Data


General
River mile1.9
Drainage area, square miles2,440
Effective hydraulic height, feet632
Maximum structural height, feet717
Overall length at crest, feet3,287
Streamflow, cfs:
Minimum of record
Mean annual
Standard project flood peaks:
  • Winter
  • Spring
Maximum of record
Probable maximum flood
250
5,727


160,000
120,000

100,000
411,000
Streamflow, acre-feet:
Minimum annual
Mean annual
Maximum annual
2,157,000
4,100,000
6,680,000
Project design discharges, cfs:
At pool elevation 1445
At pool elevation 1600:
  • Spillway
  • Outlets
    • Total at elevation 1600
32,290


150,000
40,000
190,000

220,000
Tailwater elevations:
Minimum, discharge 1,000 cfs
Maximum, at discharge 150,000 cfs
968
1,003.4
First power online1 March 1973

Estimated Cost
1 July 1973$302,000,000

Reservoir
Elevations, feet:
Maximum design pool
Maximum operating pool
Normal operating range
1605
1600
1600 to 1445
Storage capacity, acre-feet:
Gross
Usable, flood control and power
3,468,000
2,016,000
Length at elevation 1600, miles53.6
Shoreline length, miles175
Surface areas, acres:
At elevation 1600
At elevation 1445
17,090
9,050
Recreation sites, number:
Initial
Ultimate
7
19

Non-Overflows
TypeConcrete gravity
Crest elevation1613
Deck width, feet44
Concrete volume, cubic yards6,500,000
Upstream slopeVertical
Downstream slopeVertical above elevation 1560, 1 on 0.8 below
Elevators, number3

Spillway
TypeGate controlled, with stilling basin
Gates:
Type
Size, width by height, feet
Number
Tainter
50 x 56.4
2
Crest elevation1545
Crane, one, capacity, tons150

Permanent Outlet Works
Water passages:
Number
Type
Size, feet
3
Conduit
12 x 17
Gates, type and number:
Tainter
Tractor (emergency)
3
1
Intake centerline elevation1362

Powerplant
Initial installation:
Number of units
Nameplate rating, kilowatts:
  • Two, each
  • One
  • Total
3


90,000
220,000
400,000
Ultimate installation:
Number of units
Nameplate rating, KVA:
  • Two, each
  • Four, each
    Total
6


90,000
220,000
1,060,000
Powerhouse length, feet428
Turbine typeFrancis
Turbine ratings, horsepower:
Small units
Large units
142,000
346,000
Synchronous speed, revolutions per minute:
Small units
Large units
200
128.6
Distributor centerline elevations:
Small units
Large units
969
975
Spacing, feet:
Small units
Large units
47
65
Penstock diameters:
Small units
Large units
12
19
Penstock intake elevations:
Small units
Large units
1,420.68
1,412.70
Gross head, feet632
Rated head, feet560
Minimum head, feet477
Crane:
Number
Type
Capacity, each, tons
2
Bridge
350

Relocations
Roads, miles:
Highway districts
County
2.7
24.3
Bridges, number2

Fish Hatchery, Steelhead
Attraction water pump capacity, cfs255
Capacity, adult size6,000
Yearly fingerling release:
Estimated number
Estimated total weight, pounds
3,360,000
420,000