Project: Bonneville 1:55-scale Spillway General Model
PI: Bill Preslan
Project Description/Activities/Capabilities:
1:55-scale Bonneville physical spillway general model used to evaluate spill patterns for optimal
passage of juvenile salmon.
Sponsor: Portland District. POC Laurie Ebner
CHL Personnel: Bill Preslan, John Ashley, Van Stewart, TEM Murphy, Rusty Henderson
Project Location and Description:
Bonneville Dam is about 6400 feet long and includes two powerhouses, a spillway, two navigation
locks, multiple fish ladders, and four islands. A total of six 59-megawatt units and eight 77-
megawatt turbines reside in Powerhouse No. 1 and No. 2, respectfully. The 18-bay spillway is
approximately 1100 feet long, and has twelve 50.75-ft-high vertical lift gates and six 60-ft-high
wheel gates. The spillway crest is located at elevation 24 with a normal pool elevation ranging
from 71.5 to 76.5. Spillway bays 4 through 15 and 18 have deflectors that are 12 ft long and are
located at el 14. The stilling basin is a horizontal apron-type with a double row of sloping baffle
blocks. The stilling basin is 147 ft long with an invert elevation of -16 for the first 71 ft and drops
to el -24 for the remaining length. An irregular concrete apron is at the end of the stilling basin
and usually slopes downward to the tailrace topography. The old lock is76 ft wide by 500 ft long.
It discharges into a navigation channel that joins the releases from Powerhouse No. 1
approximately 1200 ft downstream of the lock. The new lock is 86 feet by 675 feet and
discharges into a channel that joins the discharge from the remainder of the project about 2600 ft
downstream of the lock. Powerhouse discharges and lock operation only indirectly influence the
spillway flow conditions by changing the local tailwater elevation.
Facilities: Bldg. 3051
Related Topic Areas: Physical models, salmon migration, fish passage, flow deflectors, surface
water, reservoirs, rivers, hydraulic structures
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