engineering

McNary Dam

McNary Dam is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand McNary Dam rather than just read about it. In short: McNary Dam is a 1.4-mile (2.2-km) long concrete gravity run-of-the-river dam which spans the Columbia River. It joins Umatilla County, Oregon with Benton County, Washington, 292 miles (470 km) upriver from the mouth of the Columbia.

Key takeaways

McNary Dam belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect McNary Dam to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of McNary Dam from memory before moving on to harder problems.

Reference excerpt

McNary Dam is a 1.4-mile (2.2-km) long concrete gravity run-of-the-river dam which spans the Columbia River. It joins Umatilla County, Oregon with Benton County, Washington, 292 miles (470 km) upriver from the mouth of the Columbia. It is operated by the U.S. Army Corps of Engineers' McNary Lock and Dam office. The dam is located a mile (2 km) east of the town of Umatilla, Oregon, and 8 miles (13 km) north of Hermiston, Oregon. The dam was originally planned to be named Umatilla Dam, but the Flood Control Act of 1945 renamed the dam in honor of Senator Charles L. McNary of Oregon, who had died in February 1944. The dam provides for slackwater navigation, hydroelectric power generation, recreation, wildlife habitat, and incidental irrigation.

Bills for the construction of a dam were introduced in the United States Congress as early as 1931. The United States House of Representatives rivers and harbors committee initially approved the project in April 1941; navigation, power generation, and national security were the major reasons cited for construction of the dam. Construction began in 1947, and was completed in 1954. Activation of all generating units was completed in 1957. Its capacity is 980 MW. There are two fish ladders for salmon and steelhead passage, one on each shore of the dam. The Washington side also has an 86-foot (26 m) wide, 683 foot (208 m) long navigation lock that lifts boats an average of 75 feet (23 m). The dam flooded the Umatilla Rapids, forming a reservoir called Lake Wallula. The lake extends 64 miles (103 km) up the Columbia to the US DOE Hanford Site. It also extends up the Snake River to Ice Harbor Dam. As with some other dams, it has two additional turbines whose purpose is to power the dam itself. That is, this dam is entirely self-sustaining. In the event of a large-scale grid outage, McNary would provide the black start capability necessary to restart other generation facilities. These two "station service" turbines are only capable of providing about three MW, compared to the 70 MW each of the other 14 turbines produce. These two turbines alternate service duty to provide the dam with its energy requirements. The dam is equipped with three large "fishway" pumps which provide water to supplement the mostly gravity-fed fish ladders. These units are constructed like smaller versions of the main turbines which run "in reverse." McNary Dam is part of the Columbia River Basin system of dams and is one of fourteen hydropower facilities belonging to the Federal Columbia River Power System (FCRPS). Stats:

Altitude: 344 feet (105 m) above sea level Height: 183 feet (56 m) Length: 7,365 feet (2,245 m) Navigation lock: Single-lift 86 feet (26 m) wide 683 feet (208 m) long Powerhouse Fourteen 70,000-kilowatt units Total capacity: 980 megawatts Overload capacity: 1,127 MW Spillway Gates: 22 Length: 1,310 feet (400 m)

Illustrations

Worked examples

Example 1 — a first encounter with McNary Dam

Start with the simplest possible case. Write down what McNary Dam claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to McNary Dam before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about McNary Dam ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of McNary Dam

In research: McNary Dam appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses McNary Dam in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: McNary Dam is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1954 establishments in Oregon, 1954 establishments in Washington (state), Buildings and structures in Benton County, Washington, so understanding it makes those chapters shorter.
In everyday life: Look for McNary Dam outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study McNary Dam in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what McNary Dam means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain McNary Dam out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is McNary Dam in simple terms?

Why does McNary Dam matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study McNary Dam?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on McNary Dam.