engineering

Navajo Dam

Navajo 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 Navajo Dam rather than just read about it. In short: Navajo Dam is a dam on the San Juan River, a tributary of the Colorado River, in northwestern New Mexico in the United States. The 402-foot (123 m) high earthen dam is situated in the foothills of the San Juan Mountains about 44 miles (71 km) upstream and east of Farmington, New Mexico.

Key takeaways

Navajo 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 Navajo Dam to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Navajo Dam from memory before moving on to harder problems.

Reference excerpt

Navajo Dam is a dam on the San Juan River, a tributary of the Colorado River, in northwestern New Mexico in the United States. The 402-foot (123 m) high earthen dam is situated in the foothills of the San Juan Mountains about 44 miles (71 km) upstream and east of Farmington, New Mexico. It was built by the U.S. Bureau of Reclamation (Reclamation) in the 1960s to provide flood control, irrigation, domestic and industrial water supply, and storage for droughts. A small hydroelectric power plant was added in the 1980s. The dam is a major feature of the Colorado River Storage Project, which is designed to regulate water resources across the entire Upper Colorado River Basin. The reservoir, Navajo Lake, is a popular recreation area and one of the largest bodies of water in New Mexico, with its upper portion extending into Colorado.

Specifications

Navajo is a rolled earthfill embankment dam, composed of three "zones" of alternating cobbles, gravel, sand and clay. The dam is 402 feet (123 m) high and 3,648 feet (1,112 m) long, with a width of 2,566 feet (782 m) at the base and 30 feet (9.1 m) at the crest. The dam contains 26,840,863 cubic yards (20,520,000 m3) of material. The crest of the dam is 6,108 feet (1,862 m) above sea level. The dam forms Navajo Lake, one of the largest lakes in both New Mexico and Colorado with up to 15,610 acres (6,320 ha) of surface water. Navajo Lake extends for 35 miles (56 km) up the San Juan River, 13 miles (21 km) up the Los Pinos River (Pine River) and 4 miles (6.4 km) up the Piedra River. The capacity of Navajo Lake is 1,708,600 acre-feet (2.11 km3), of which 1,036,100 acre-feet (1.28 km3) or 60.6 percent is considered "active" or usable storage. Prior to the dam's construction, the San Juan River flow was high during spring snowmelt and summer monsoon, and a relative trickle at other times of the year. The dam has enabled a constant water flow throughout the year which benefits water supply, recreation, and flood control. Up to 1,320 cubic feet per second (37 m3/s) of water is released into the San Juan River via a 32 megawatt hydroelectric plant owned by the city of Farmington. Hydropower generated at Navajo Dam serves about 37,000 customers in northwest New Mexico and averaged a production of 135,226,000 kilowatt hours for the period 1989–1999. Floodwaters can be released through a tunnel outlet with a capacity of 4,200 cubic feet (120 m3) per second, and an ungated concrete spillway with a capacity of 34,000 cu ft/s (960 m3/s). The spillway is 138 feet (42 m) wide at the crest and falls 410 feet (120 m) through a chute to a stilling basin. Flood releases are not to exceed the safe San Juan channel capacity of 5,000 cu ft/s (140 m3/s) below the dam. When the dam was first constructed, water releases were prioritized to meet irrigation demands and provide flood control; however, since the late 1990s the operating criteria have been changed in order to meet environmental restoration goals in the San Juan River (see below). Navajo Dam is part of the federal Colorado River Storage Project (CRSP), a massive system of dams, reservoirs and irrigation projects across the Upper Colorado River Basin. Operations at Navajo Dam are crucial to ensuring enough water is available for both local San Juan basin users and contract holders of the San Juan–Chama Project, which diverts water from the San Juan River to the Rio Grande valley serving Albuquerque, New Mexico. The San Juan-Chama project uses up to 96,200 acre-feet (0.1187 km3) of water that would otherwise have flowed into Navajo Lake. At Navajo Dam, a large fraction of San Juan River water is diverted into the Navajo Indian Irrigation Project (NIIP), which irrigates 70,000 acres (28,000 ha) of farmland to the south of the river. About 508,000 acre-feet (0.627 km3), or 30 percent of the lake's capacity, are allocated to the NIIP. Current water use by NIIP is about 200,000 acre-feet (0.25 km3) per year, and is expected to increase as more of the NIIP lands are brought into agricultural production. Both the San Juan-Chama and Navajo Irrigation Projects are participating units of the CRSP.

History The first studies for a dam on the San Juan River were made in 1904, but there was little need for such a project at the time, due to the remoteness of the area. The growth of Farmington and surrounding towns in the 1920s due to agriculture and a petroleum boom created the need for additional water supply as well as flood control, both equal in importance due to the seasonal nature of the San Juan River. The Navajo Nation's growing population was suffering from food and employment shortages, which the Bureau of Reclamation envisioned could be solved by a large irrigation project. The 1908 Supreme Court decision Winters v. United States ruled that a federally established Indian reservation was "entitled to the water needed to create a permanent homeland". In other words, the reservation carried implicit water rights dating back to its creation in 1868; in this case, the Navajo peoples' rights to San Juan River water. This ruling eventually led to development of the Navajo Dam project, which was first outlined in a 1955 Bureau of Indian Affairs report that proposed a "distribution system for irrigation of 137,250 acres (55,540 ha) of new land within and adjacent to the Navajo Indian Reservation, all in New Mexico."

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Navajo Dam

Start with the simplest possible case. Write down what Navajo 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 Navajo 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 Navajo 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 Navajo Dam

In research: Navajo 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 Navajo 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: Navajo Dam is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1962 establishments in New Mexico, Buildings and structures in Rio Arriba County, New Mexico, Buildings and structures in San Juan County, New Mexico, so understanding it makes those chapters shorter.
In everyday life: Look for Navajo 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 Navajo Dam in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Navajo 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 Navajo Dam out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Navajo Dam in simple terms?

Why does Navajo 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 Navajo 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 Navajo Dam.