# What Is the Highest Dam in the United States?

> Oroville Dam in Northern California is the highest, or tallest, dam in the United States when dams are compared by structural height. The earth-fill embankment rises 770 feet from its foundation to its crest. It crosses the Feather River near the city...

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Byline: ARGO.net Editorial Team
Published: 2026-08-22T10:10:32+00:00
Categories: Explainer, Water

![Oroville Dam in Northern California](https://www.argo.net/wp-content/uploads/2026/08/verified_featured_52441.jpg)

Oroville Dam in Northern California is the highest, or tallest, dam in the United States when dams are compared by structural height. The earth-fill embankment rises 770 feet from its foundation to its crest. It crosses the Feather River near the city of Oroville and impounds Lake Oroville, the largest reservoir in California's State Water Project.

"Highest" refers here to the height of the dam structure, not its elevation above sea level. Oroville Dam's crest is far lower in elevation than many small mountain dams. Reservoir water level is another separate measurement that rises and falls with storage. Using a consistent structural-height definition is what places Oroville above Hoover Dam and Glen Canyon Dam.

## How dam height is measured

Structural height measures the vertical distance from the lowest point of the excavated foundation to the top of the dam. Hydraulic height describes the difference between a defined downstream point and a water-control elevation. Height above the streambed excludes foundation material buried below the former channel. Those values can differ by many feet for the same structure.

The U.S. Army Corps of Engineers' [National Inventory of Dams data service](https://geospatial.sec.usace.army.mil/dls/rest/services/NID/National_Inventory_of_Dams_Public_Service/MapServer/layers) keeps separate fields for dam height, hydraulic height and structural height. Rankings compiled from different fields will not necessarily match. Published descriptions may also round to the nearest foot.

Elevation is a location measured against a vertical datum such as mean sea level. A dam with a crest elevation of 9,000 feet could stand only 50 feet above its foundation. Lake elevation tells operators where the water surface sits on the same datum. It does not describe the dam's physical height and it changes from day to day.

## Oroville Dam's 770-foot structure

The California Department of Water Resources identifies [Oroville Dam as the nation's tallest earth-fill dam](https://water.ca.gov/programs/state-water-project/swp-facilities/oroville) at 770 feet. It is built from compacted earth and rock with zones designed to control seepage and provide strength. The broad embankment has a narrow crest thousands of feet long and a much wider base.

Site work began in the early 1960s and the embankment was topped out in 1967. The dam holds back runoff from the Feather River watershed on the western slope of the Sierra Nevada. Lake Oroville stores about 3.5 million acre-feet at full capacity, subject to the elevation and survey used for the published figure.

The dam's size reflects its foundation as well as the valley it closes. Much of the 770 feet is invisible when viewed from the downstream river because structural height continues below the old ground surface to the lowest excavated foundation. Photographs remain impressive, but they are a poor measuring tool without that engineering context.

## Earth-fill differs from concrete construction

An embankment dam resists water pressure through a broad mass of compacted material. Oroville uses clay, rock and other natural materials arranged in engineered zones. Its base spreads much farther than the narrow crest. Internal filters and drains manage seepage so fine particles are not carried out of the structure.

Concrete gravity dams rely mainly on their weight, while arch dams transfer part of the load into canyon walls. Hoover is a concrete arch-gravity dam and Glen Canyon is a concrete arch dam. Their shapes, materials and sites differ from Oroville, so total material volume or apparent steepness cannot substitute for height.

Calling Oroville the tallest earth-fill dam gives the construction type and national ranking together. California DWR also sometimes calls it the tallest dam in the country. Both descriptions use the same 770-foot structural figure. Worldwide rankings require another dataset and are outside the national claim.

## How Oroville compares with Hoover Dam

Hoover Dam is the most famous tall dam in the United States, but it is shorter by structural height. The Bureau of Reclamation lists [Hoover Dam at 726.4 feet](https://usbr.gov/projects/index.php?id=122) from foundation to crest. That makes Oroville about 43.6 feet taller before rounding.

Hoover crosses the Colorado River on the Arizona-Nevada line and forms Lake Mead. Its concrete arch-gravity structure is 1,244 feet long at the crest. The Reclamation project page also lists a hydraulic height of 576 feet, showing why a dam can carry more than one valid height depending on the defined endpoints.

Lake Mead's storage capacity, Hoover's historical prominence and the steep Black Canyon setting do not change the structural ranking. A reservoir's volume is controlled by basin geometry and operating elevations as well as the barrier. The largest reservoir and tallest dam are separate superlatives.

## Glen Canyon and other tall dams

Glen Canyon Dam in Arizona rises 710 feet above bedrock, according to the [Bureau of Reclamation](https://www.usbr.gov/uc/rm/crsp/gc/index.html). It impounds Lake Powell and has a crest elevation above 3,700 feet. The high geographic elevation makes no difference to its third-place position behind Oroville and Hoover by structural height.

Other large western dams may lead in concrete volume, crest length, generating capacity or reservoir storage. Grand Coulee, for example, is an enormous concrete gravity dam whose national significance comes from power, irrigation and scale rather than a height record. A precise comparison should always name the variable.

The same caution applies internationally and to lists of natural or artificial lakes. Argo's [largest man-made lakes in Canada](https://www.argo.net/10-largest-man-made-lakes-in-canada/) ranks water bodies by a stated lake measurement. It does not rank the dams that created them.

## Lake Oroville and the State Water Project

Lake Oroville captures winter rain and spring snowmelt for later release. The reservoir provides water storage, flood-management space, recreation and support for downstream environmental requirements. Water enters the Feather and Sacramento river channels on its path toward the Sacramento-San Joaquin Delta.

The underground Edward Hyatt Powerplant can generate electricity as water descends through the project. The broader Oroville-Thermalito complex also includes a forebay, an afterbay and pumping-generating facilities. California DWR's [federal project description](https://water.ca.gov/Programs/State-Water-Project/SWP-Facilities/Oroville/HLPCO-Oroville-Facilities-Project-2100) treats the dam, reservoir and associated facilities as one operating system.

Flood operations reserve space for incoming runoff and release water according to forecasts, conditions and downstream limits. A reservoir elevation reported in a daily update describes current storage, not the dam's height. For another example of fluctuating western storage, see Argo's [Colorado River reservoir levels](https://www.argo.net/colorado-river-reservoir-levels-today/).

## Power, flood management and fish

Hydropower uses the vertical drop and flow of water through turbines. Hyatt Powerplant sits underground in the left abutment and works with the Thermalito facilities. Pump-back operation can return water to higher storage during off-peak periods, allowing generation when electricity demand is greater.

The dam also blocked access to upstream spawning habitat for salmon and steelhead. The Feather River Fish Hatchery was built below the dam as mitigation and DWR dates its construction to 1966 and 1967. A hatchery replaces some fish production, but it does not recreate the former river connection.

Reservoirs produce tradeoffs across water supply, energy, flood risk, recreation and ecosystems. Comparing only height says nothing about how successfully a project balances those purposes. It simply answers a structural question with a measurable definition.

## Spillways are separate from the dam body

Spillways carry water past a dam when releases exceed powerplant or outlet capacity. Oroville's main gated spillway descends beside the embankment, while an emergency spillway provides an additional route at high reservoir levels. These structures protect the dam by controlling where large flows go.

In February 2017, severe erosion damaged the main spillway and the area below the emergency spillway. Evacuations and subsequent reconstruction focused national attention on the complex. The event did not mean the earth-fill dam had failed and it did not alter its structural height. DWR's [spillway background](https://water.ca.gov/Programs/State-Water-Project/SWP-Facilities/Oroville/Oroville-Spillways/Background) distinguishes the damaged release structures from the dam embankment.

Dam safety involves monitoring seepage, movement, instrumentation and outlet reliability as well as inspecting visible concrete. Owners plan for floods and earthquakes, maintain gates and update emergency action plans. A record-setting dimension creates no exemption from routine engineering oversight.

## The record in context

Oroville Dam is the straightforward answer to the national height question: 770 feet by structural height. Hoover follows at 726.4 feet and Glen Canyon stands 710 feet above bedrock. The figures are compatible because each represents the dam structure from its foundation or bedrock to its crest, rather than the changing surface of the reservoir.

Lake Oroville is a reservoir, so it belongs in a different category from natural lakes featured in [15 famous U.S. lakes](https://www.argo.net/15-famous-lakes-in-the-united-states/). Likewise, Colorado's deepest natural lake and its largest reservoirs answer separate questions, as explained in [Colorado's deepest lake](https://www.argo.net/what-is-the-deepest-lake-in-colorado/). Clear definitions keep a memorable superlative from becoming a misleading one.