Guri Dam: Venezuela's Hydroelectric Giant on the Caroní River

**Guri Dam** (officially Simón Bolívar Hydroelectric Plant) on the Caroní River in Bolívar State, Venezuela, is one of the world's largest hydroelectric power stations, with an installed capacity of **10,235 MW**. Completed in its current form in 1986 after a construction program spanning two decades, the dam supplies approximately **60-70 percent of Venezuela's total electricity**, making the country extraordinarily dependent on this single facility.

Introduction

The dam is located in the **Guiana Highlands**, a region of ancient Precambrian rock, tabletop mountains (tepuis), and pristine tropical forest that is among the most geologically ancient and biodiverse landscapes on Earth. The Caroní River, fed by the highlands' abundant rainfall, provides one of the most consistent and voluminous water flows of any hydroelectric dam site in the world.

Engineering & Structure

• Type: Concrete gravity and earth-fill dam
• Height: 162 meters
• Crest Length: 7,426 meters (total, including earth dams)
• Turbines: 20 units (10 × 730 MW + 10 × 260/400 MW)

Guri Dam consists of a concrete gravity section and extensive earth-fill wing dams, with a total crest length exceeding 7.4 kilometers. The concrete section rises 162 meters above the riverbed and houses the spillway. The dam was built in two phases: the first (1963-1978) included 10 smaller generating units, and the second (1978-1986) added 10 larger 730 MW units, bringing total capacity to 10,235 MW.

The 10 larger turbines are among the most powerful individual units in the Western Hemisphere, each generating 730 MW. The dam's reservoir, **Guri Lake**, has a surface area of approximately 4,250 square kilometers, making it one of the largest artificial lakes in the world. The spillway can discharge up to 25,400 cubic meters per second.

Geographic Setting

• River: Caroní River (Orinoco tributary)
• Location: Bolívar State, Venezuela
• Coordinates: 7.76°N, 63.00°W
• Reservoir Area: ~4,250 km²

The Caroní River drains the western portion of the Guiana Highlands, a Precambrian shield of rocks over 1.7 billion years old. The river descends from the Gran Sabana — a vast savanna plateau dotted with tepuis (table-top mountains), including the one that inspired Arthur Conan Doyle's *The Lost World*. Angel Falls, the world's highest waterfall at 979 meters, is located on the Churun River, a Caroní tributary.

The dam site lies at the transition between the highlands and the Orinoco lowlands. The surrounding landscape is a mosaic of tropical savanna and dense lowland forest. The Caroní's basin receives 2,000 to 3,000 millimeters of rainfall annually, making it one of the wettest river basins in South America. This abundant rainfall provides the reliable, high-volume flow that makes Guri so productive.

Hydroelectric Power

• Installed Capacity: 10,235 MW
• Annual Output: ~47 TWh (in normal conditions)
• National Share: 60-70% of Venezuela's electricity
• Drought Vulnerability: Severe power crises during El Niño droughts

Guri Dam generates approximately 47 terawatt-hours in years of normal rainfall, making it one of the most productive hydroelectric stations on Earth. Its output powers virtually all of northern Venezuela, including Caracas, and supplies the energy-intensive aluminium and steel industries of Ciudad Guayana. Venezuela's extreme dependence on this single facility is both a testament to its productivity and a critical vulnerability.

During El Niño drought events, reduced rainfall in the Guiana Highlands can drop Guri Lake to dangerously low levels. In 2010 and again in 2016 and 2019-2020, severe droughts forced nationwide electricity rationing, with rolling blackouts affecting millions. The 2019 blackout, which lasted several days in some regions, was exacerbated by years of underinvestment and mismanagement of Venezuela's electrical infrastructure under economic crisis.

Environmental & Social Impact

• Forest Flooded: ~4,250 km² of tropical forest and savanna
• People Displaced: ~5,000 families (1960s-1980s)
• Blackout Crisis: Nationwide power failures during droughts

The creation of Guri Lake flooded approximately 4,250 square kilometers of tropical forest and savanna, affecting wildlife habitat and displacing several thousand families from the reservoir area. The flooded forest produced significant methane emissions during the early decades as biomass decomposed underwater, though emissions have declined as the reservoir matured.

Venezuela's electricity crisis has made Guri Dam a symbol of the country's broader economic collapse. Once a showcase of Venezuelan engineering prowess, the dam's output has been compromised by neglected maintenance, loss of skilled technical staff due to emigration, and political mismanagement. Transmission line failures in 2019 caused a nationwide blackout that affected hospitals, water treatment plants, and communications for days.

Key Facts

• Guri Dam generates 10,235 MW, supplying 60-70% of Venezuela's electricity.
• Guri Lake's surface area of ~4,250 km² makes it one of the world's largest artificial lakes.
• The dam is located in the Guiana Highlands, one of Earth's most ancient geological formations.
• Severe droughts have caused nationwide power crises in 2010, 2016, and 2019-2020.
• The Caroní basin includes Angel Falls, the world's highest waterfall.

Fun Facts

• The Guiana Highlands rock beneath Guri Dam is over 1.7 billion years old — among the most ancient exposed rock on Earth's surface.
• Venezuela's 2019 nationwide blackout, triggered partly by Guri-related transmission failures, was one of the most widespread power failures in world history.
• The tepui table-top mountains visible from Guri Lake have been isolated for so long that they harbor species found nowhere else on Earth — they are sometimes called "islands in the sky."

Final Thoughts

Guri Dam demonstrates both the extraordinary potential and the extreme risk of concentrating a nation's electricity supply in a single hydroelectric facility. Located amid one of the most ancient and beautiful landscapes on Earth, it has powered Venezuela's development for decades — but drought, neglect, and political crisis have revealed the fragility of this dependence.