Fact Sheet
US Army Corps of Engineers
U.S. Army Engineer Research and Development Center
April 2004
Public Affairs Office | 3909 Halls Ferry Road | Vicksburg, MS 39180-6199 | (601) 634-2504 | http://www.erdc.usace.army.mil
Chief Joseph General Model
Purpose: To evaluate spillway flow deflector impacts on hydraulic conditions in and downstream of the spillway stilling basin.
Background: Chief Joseph Dam (CJD) stretches
over one mile across the rolling Columbia River at
river mile 545.1. Behind the dam, lies Rufus Woods
Lake, which extends 51 miles upstream to Grand
Coulee Dam. CJD discharges into Lake Pateros,
which extends 29.5 miles to Wells Dam. CJD is the
Corps' largest power-producing dam. The
powerhouse consists of 27 main generators with a
hydraulic capacity of 219 kcfs and a nameplate
capacity of 2069 MW. The Chief Joseph
powerhouse is oriented in an east-west direction
about 90 degrees to the spillway. The spillway at
CJD has a total length of 980 ft and consists of 19
radial gate-controlled bays. The width of each bay is
49 ft as measured from the centerline of the piers,
and the radial gates have a width of 36 ft. Piers, 13
ft in maximum width, separate the bays. The
spillbays are numbered from 1 to 19 from north to
south. The elevation of the spillway crest is 901.50
ft. The operating pool for Rufus Woods Lake ranges
from elevation 950 to 956 ft. The tailwater elevation typically ranges between elevations of 780 to 790 ft depending upon the
total river flow and Lake Pateros pool elevation. The stilling basin at CJD has a length of 167 ft and a stepped end sill with a
height of 11 ft. Energy dissipation is provided by a series of baffle blocks located near the end of the stilling basin with a height
of 11 ft. The invert elevation of the stilling basin apron is at 743 ft resulting in a typical depth of flow about 36-42 ft. An end
wall extending the length of the stilling basin bounds the north side of the spillway adjacent to bay 1. The tailwater channel bed
elevation varies in elevation downstream of the end sill ranging in elevation from 740 downstream of bays 6 and 7 to elevation of
755 ft downstream of bays 9 through 19. The channel bed elevation gradually rises in elevation downstream of the spillway to an
elevation of about 755 ft downstream of the powerhouse.
Facts: At the request of the U.S. Army Engineer District, Seattle, a 1:80 scale physical model was designed and constructed at
the U.S. Army Engineer Research and Development Center by the Coastal and Hydraulics Laboratory. The model reproduces
the spillway and powerhouse of the Chief Joseph Dam, and sufficient upper pool and tailrace length to reproduce prototype flow
conditions near the structure. The model was used to evaluate the spillway flow deflectors and stilling basin performance.
Points of Contact: For additional information, please contact
Mr. Glenn Davis at 601-634-4183 ( ),
Mr. Dwayne Fuller at 601-634-2668 ( ) or
Mr. Dennis Markle at 601-634-3680 ( )
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