How big is Lake Powell?

Lake Powell is one of the largest man-made reservoirs in the United States, both in terms of surface area and water capacity. Situated on the Colorado River, straddling the border between southeastern Utah and northeastern Arizona, Lake Powell is a striking example of engineering and natural beauty combined. Its immense size and intricate shoreline make it a prime destination for recreation, research, and water management in the arid American Southwest.

Surface Area and Length

At full pool (maximum capacity), Lake Powell stretches about 186 miles (299 kilometers) in length from Glen Canyon Dam near Page, Arizona, to the confluence of the Colorado and Dirty Devil Rivers in Utah. The lake's surface area at full capacity is approximately 161,390 acres, or around 252 square miles (653 square kilometers). This makes Lake Powell the second-largest reservoir in the United States by surface area, just after Lake Mead, located downstream.

Water Capacity

In terms of volume, Lake Powell has a maximum storage capacity of about 24.3 million acre-feet of water. An acre-foot is the volume of water required to cover one acre of land to a depth of one foot — about 325,851 gallons. This means Lake Powell can store nearly 7.9 trillion gallons (30 trillion liters) of water when completely full.

The reservoir plays a vital role in the Colorado River Storage Project, helping to regulate water flow to the Lower Basin states (Arizona, Nevada, and California) and ensuring compliance with the Colorado River Compact of 1922.

Shoreline and Canyons

One of Lake Powell’s most fascinating features is its sprawling and jagged shoreline. When full, the lake boasts nearly 1,960 miles (3,150 kilometers) of shoreline — longer than the entire west coast of the continental United States. This intricate shoreline is a result of the flooded side canyons of Glen Canyon, including popular spots like Antelope Canyon, Labyrinth Canyon, and Cathedral Canyon.

Elevation

The full pool elevation of Lake Powell is approximately 3,700 feet (1,127 meters) above sea level. However, due to prolonged drought conditions and increasing water demands, the lake often operates below this level. In recent years, water levels have fluctuated significantly, impacting recreational access, hydroelectric power generation, and ecosystem health.

Summary

Lake Powell is massive both in scale and significance. Its 186-mile length, 252 square-mile surface area, 24.3 million acre-feet storage capacity, and nearly 2,000-mile shoreline make it one of the most important and impressive reservoirs in the United States. While it offers breathtaking scenery and ample recreational opportunities, it also stands at the center of ongoing discussions about water management, climate change, and sustainability in the American West.