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TRENTON DAM Missouri River Basin Project—Nebraska

General Information


Purpose: Flood control, diversion for irrigation, storage, sedimentation control, fish and wildlife preservation, and recreation Location: On Republican River, about

2-1/2 miles west of Trenton, Nebr. Constructed: 1949-1953 Water supply: Republican River Drainage area: 4, 003 square


Maximum flood: 200, 000 secondfeet (May 31, 1935) Average yearly flow: 211 secondfeet (1947-1952) Reservoir:

Official name: Swanson Lake
Area: 7,975 acres at elevation


Flood control storage: 133, 800
acre-feet, between elevations
2752.0 and 2773.0
Active irrigation storage: 116,100
acre-feet, between elevations
2710.0 and 2752.0
Dead storage: 4, 100 acre-feet,
between elevations 2693. 0 and

"Type: Zoned rolled-earth fill
Foundation: Pierre shale
Slope protection: Riprap on gravel
blanket on upstream face, seeded
topsoil on downstream face

Height: 144 feet above lowest ex-
cavation in cutoff trench, 100
feet above riverbed
Crest length: 8, 600 feet
Crest elevation: 2793.0
Crest roadway width: 30 feet
Volume: 7, 800, 000 cubic yards
Slopes: Upstream, 6 to 1 to ele-
vation 2710, 3 to 1 to elevation
2760, and 2-1/2 to 1 to eleva-
tion 2793

Downstream, 10 to 1 to elevation 2710, 4 to 1 to elevation 2735, 2-1/2 to 1 to elevation 2760, and 2 to 1 to elevation 2793

Dam (Continued)

Main cutoff trench: 50-foot base width

with 1-1/2 to 1 side slopes, length

about 6, 760 feet
Auxiliary cutoff trench: 50-foot base

width with 1-1/2 to 1 side slopes,

length about 570 feet


Type: Concrete overflow chute type
with stilling basin

Crest length of overflow section: 126

Crest: Elevation 2743. 00

Maximum discharge: 126, 500 secondfeet at water surface elevation 2785. 6 (as determined by model studies)

Gates: Three, 42 by 30 feet

Stilling basin: Reinforced concrete with dentated sills

River Outlets

Outlets: Two

Invert: Elevation 2710. 00

Gates: Four, 6 by 7. 5 feet (two are installed in each outlet)

Discharge capacity: 1, 000 second-feet with reservoir water surface elevation at 2720.0

Canal Outlet Works

Intake structure:

Vertical shaft: 50 feet high
Sill elevation: 2710.00

Outlet conduit: 5 feet 6 inches in diam-
eter, 208 feet long

Outlet pipe: 56-inch-diameter pipe in horseshoe conduit, 244 feet long

Gates: Two, 4 by 4 feet (one is installed in the emergency gate chamber and the other in the control house)

Discharge capacity: 300 second-feet with reservoir water surface elevation 2720.0, and canal water elevation 2705.0

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Technical records of design and construction are a series of publications which record the planning, design, construction, and initial operation of Bureau of Reclamation projects and features.

This technical record of design and construction of Trenton Dam is divided into six chapters. Chapter I contains general description, history and authorization, geology, and cost information. Chapter II is devoted to investigations of construction materials, and studies of railroad, highway, and county road relocations. Discussions on the design of the dam, spillway and river outlets, canal outlet works, and railroad structures .are included in chapter III. Chapter IV contains discussions on contract administration and survey work. All phases of construction are discussed in chapter V. Chapter VI is devoted to test installations .

This technical record was prepared in the Commissioner's Office, Denver, under the direction of the Assistant Commissioner and Chief Engineer. Acknowledgment is gratefully made to the designers and field personnel whose contributions formed the basis for this work.

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