America’s Most Unusual Creek Only Appears Every Summer In These Sand Dunes

The Medano Creek at Great Sand Dunes National Park

Flowing through the eastern edge of Great Sand Dunes National Park in southern Colorado’s San Luis Valley, this seasonal river only appears from April to June.

The creek creates waves in a pattern called “surge flow,” making it feel like a beach in the middle of the desert.

People have been visiting the creek since the 1920s, though Native Americans knew about it for thousands of years before that. Here’s what you need to know today.

Great Sand Dunes National Park

The mix of creeks, mountains, and dunes makes this park different from any other place in North America. For one, it’s home to the tallest dune field, Star Dune reaching 750 feet high.

Covering 149,028 acres, the land includes the lowest point near San Luis Lakes at 7,520 feet to the highest 13,604 feet point at Tijeras Peak. The dunes were formed by southwest winds carrying sand toward the Sangre de Cristo Range, and seasonal streams like Medano Creek also contributed sediment to its geology.

How Surge Flow Creates Waves

The creek’s water creates unusual waves that appear every 20 seconds because of how it flows over the sand.

Small sand dams form and break apart repeatedly, making waves up to 6 inches high, depending on snowpack levels upstream. Peak wave activity typically occurs in late May or early June when snowmelt is at its highest.

The Creek’s Changing Path

The creek doesn’t follow the same path each year like most rivers do. Its channel can move up to 500 feet between seasons as the sand dunes shift and change shape.

Each season brings new beaches, sandbars, and pools as the water finds different ways through the sand. This movement keeps plants from growing permanently in certain areas, which helps maintain the dune field’s natural state.

Seasonal Water Flow

The creek runs full in late May when the mountain snow melts from peaks that are 14,000 feet high. During this peak time, the creek can spread 50 feet wide and get up to 2 feet deep in some spots.

The water stays cold, between 45 and 55 degrees Fahrenheit, because it comes straight from melting snow. Native fish like the Rio Grande cutthroat trout (Colorado’s state fish) use these cold waters during their seasonal moves.

Water Movement Under the Sand

A lot of the creek’s water flows underground through layers of sand up to 15 feet deep. This hidden water helps special desert plants survive, including prairie sunflowers and desert paintbrush.

Other species that benefit from this hidden water include various grasses and shrubs adapted to sandy soils, such as rabbitbrush and yucca. Even when you can’t see water on the surface, it continues flowing underground for up to two months.

Wildlife Around the Creek

The creek creates a strip of wet habitat that attracts more than 50 types of birds (sandpipers and mountain bluebirds) and several kinds of amphibians. Birds like American avocets and killdeer visit the creek, while tiger salamanders breed in its temporary pools.

Some plants that grow near the creek, like the Great Sand Dunes skeletonplant, don’t exist anywhere else in the world. These plants have adapted specially to grow in sandy soil that’s only wet part of the year.

Camping in the High Desert

You can camp at Piñon Flats Campground, which sits 8,200 feet above sea level and offers 88 single-family campsites, some of which can accommodate RVs up to 35 feet in length. The temperature here can change by 40 degrees between day and night.

The campground gives you clear views of both the dunes and the creek bed. Because the air is so clear at this height, it’s one of the best places (typically open from April through October) in Colorado to see stars at night.

Sand Sports on the Dunes

Once the creek dries up in mid-July, people use the dunes for sandboarding. The dunes slope up to 35 degrees and are made of quartz, feldspar, and mica, which makes them perfect for sliding.

The best time to sandboard is early morning when the sand is cool and slightly firm. The steepest dunes in the park are located near the center of the dune field. By afternoon, the sand can get as hot as 150 degrees Fahrenheit, making it too hot for activities.

Mountain Trails and Hiking

The trailhead paths lead to six mountain lakes and high meadows where rare plants like the Colorado tansy-aster grow. Accessible via the Sand Creek Trail, the Sand Creek Lakes are located in the northeastern section of the park, offering hikers a chance to explore alpine lakes and view peaks exceeding 13,000 feet.

Photography at the Park

At sunrise and sunset, the dunes make long shadows that create striking patterns. Photographers use special high-speed cameras to capture the creek’s wave patterns, showing water movements that happen too fast to see (like 20 seconds tops).

When conditions are right, the creek’s shallow water can reflect the dunes like a mirror, best viewed after recent rains or during peak snowmelt.

Four-Wheel Drive Route

The Medano Pass Primitive Road is a challenging 22-mile drive that crosses the creek nine times before reaching 10,000 feet elevation. The creek crossings can be up to 18 inches deep when water flow is highest.

Drivers pass through five different environments, from the sandy desert to lush forests. To drive on the sandy parts, you need to lower your tire pressure to 20 PSI or less, so don’t forget to carry a portable air compressor.