Grand Coulee

Grand Coulee is a deep valley in Washington carved between steep cliffs and wide plains that run for miles. Dry Falls marks a dramatic point in the landscape, and a series of lakes and dams now regulate water flow through the region.

Around 18,000 years ago, enormous floods from melting glaciers carved this valley through basalt and granite rocks when an ice barrier suddenly broke. A major dam was later built to generate electricity and deliver water for farming across the region.

The valley shaped by irrigation systems shows how water management changed the land for farming. Local communities rely on the lakes and channels for agriculture and recreation today.

Spring and fall offer the most comfortable weather for exploring the valley, with clear skies that highlight the cliff formations. The area works well for hiking, swimming, and bird watching, and many of the main sights can be reached from nearby roads.

Scientists discovered evidence of ancient Ice Age floods preserved in the rock formations throughout the valley. These geological clues tell the story of how water shaped this landscape thousands of years ago.

Location: Grant County

GPS coordinates: 47.62000,-119.30800

Latest update: December 20, 2025 15:42