1969 810mw Lower Monumental Lock and Dam on Snake River

(Satellite)

USACE
"The powerhouse has six 135,000-kilowatt units. Power generated during fiscal year 2017 was 2.67 billion kilowatt hours. This is a single-lift lock, 86 feet wide by 666 feet long, with a 100-foot vertical lift. About 2,903,090 tons of commodities passed through the navigation lock during fiscal year 2021. The cargo primarily consisted of grains, petroleum products, fertilizer and wood products. There are two fish ladders for migrating adult salmon and steelhead to use. Modifications to improve adult Pacific lamprey passage include installation of passage structures and metal plating to assist lamprey upstream. In 2007, a spillway weir was installed to improve conditions for juvenile fish passage at the dam. The 10-year average collection of outgoing juvenile salmon and steelhead for 2011 to 2020 at Lower Monumental was approximately 2.2 million fish with approximately 1.7 million of those transported via truck and barge below Bonneville Dam."
The eight Tainter gates are 50'W x 60'H. The peak discharge is 850kcfs.
The Kaplan turbine has six 26' blades and generates 212,400hp at 90rpm.

USACE-crso
"Lower Monumental Lock and Dam was the second of four dams constructed as part of the Lower Snake River Project, authorized in the Rivers and Harbors Act of 1945. Construction began in 1961, and three turbine units were operational in 1970. Three more units were operational in 1978. Lake Herbert G. West extends upstream of the dam for 28 miles to Little Goose Dam."
The hydraulic capacity is 130kcfs.

CapitalPress, U.S. Army Corps of Engineers (source)

Lower Monumental Lock and Dam - Walla Walla USACE posted

USACE-nwd
"It is 3,791 feet long, with an effective height of about 100 feet. The dam is a concrete gravity-type dam, with earthfill abutment embankments."

USACE-images

Vance Robbins, Jul 2021, cropped

Michael Larsen, Jun 2022

 

Andy Michel posted
Stuck in the lock at LoMo   Tri-City Herald    August 13th, 1979

Lower Monumental Lock and Dam - Walla Walla USACE posted two photos with the comment: "Lower Monumental Lock and Dam, 2002: Over two days during the winter of 2002, construction workers at Lower Monumental Dam poured about 2,200 cubic yards of concrete into two large holes in the dam’s stilling basin, an area in front of the dam used to dissipate the force of the water coming through the spillway gates. In the basin, bubble screens deterred fish from the project area and biologists monitored the water quality. Construction continued through mid-February as workers installed new spill deflectors to improve fish passage conditions."

1

2

oxboinc
During the Winter of 2010-11, the gate was replaced. It was fabricated and shipped on a barge as three sections.

USACE-20210201
[I don't know if this is the lock for this dam. If not, it is a similar lock.]
"he U.S. Army Corps of Engineers’ Portland and Walla Walla districts will close all Corps navigation locks on the Columbia and Snake rivers March 6 at 6 a.m[, 2021]. for regularly-scheduled annual inspections, preventative maintenance and repairs." A routine maintenance closure is two weeks.

union-bulletin, Seattle Times file photo by STEVE RINGMAN
The road across the dam was closed during May, 2022, to greese some trunnions that originally were designed to be unlubricated.
[USACE press release]

WallaWallaUSACE posted, May 18, 2022
Lower Monumental Dam reopens public dam crossing
Officials at Lower Monumental Lock and Dam have reopened dam crossings to the public after completing spillway gate repairs.
Read more: https://www.nww.usace.army.mil/Media/News-Releases/Article/3035449/22-032-lower-monumental-dam-reopens-public-dam-crossing/
Lower Monumental Lock and Dam - Walla Walla USACE shared

WallaWallaUSACE posted
LTC ShaiLin KingSlack, Commander of the Walla Walla District, and Tyler Hutton, Power Plant Mechanic Worker In Charge at Lower Monumental Lock and Dam, looking up at the sheave for Lower Monumental's vertical lift gate 1.
A sheave is a wheel that moves ropes through a pulley mechanism. This sheave is part of the mechanism that lifts the Lower Monumental navigation lock gate.
Fort Loudoun Lock shared
Another example of the tremendous scale & size of the equipment it takes to get the job done in many cases around the Corps.