GREAT SAND DUNES NATIONAL PARK AND PRESERVE — A favorite destination for many San Luis Valley residents and tourists this weekend will be Medano Creek.

On a recent visit, the creek was running wide (about 100 yards) and very shallow. Most of the creek was between one –two inches deep with one channel that was six to seven inches deep. According to the National Park Service, the peak flow of the creek is about 40 cubic feet per second (cfs) and peaked at 21 cfs on May 31-June 1.

According to the official park service report the current conditions are: Medano Creek has a shallow to moderate flow at the Dunes Parking Lot. The creek is flowing in braided channels about 1-5 inches (2-13 cm) deep. There are small surges 1-4 inches (2-10 cm) high in some channels, but not enough water for floating. Flow is typically highest at dawn, and lowest at dusk. These conditions are typical of late June.

The beginning of June is the best opportunity to experience "surge flow", where waves flow down across the sand. The water is not deep enough in 2024 for floating.

Because of the creek's popularity, early June weekends are extremely crowded, with long lines of traffic, overflowing parking lots, a crowded beach, and full campgrounds. If possible, plan your visit on a weekday this time of year.

As the creek becomes much lower around the second week of June, mosquitos emerge in large numbers. Move away from vegetation, to the far side of the creek to avoid the worst of the mosquitos: they don't like open sand but prefer to be near shady bushes and trees.

Although mountain snowpack in many parts of Colorado is above average, the watershed in the Sangre de Cristo Mountains that constitutes Medano Creek is about 5% of average leaving the creek with less water than banner years.

Medano Creek is one of the few places in the world where the phenomenon of surge flow can be experienced. Surge flow is a stream flowing in rhythmic waves on sand. Three elements are needed to produce the surge, a relatively steep gradient to give the stream a high velocity; a smooth, mobile creek bed, in this case, sand, with little resistance; and sufficient water to create surges. In spring and early summer, these elements combine to make the waves. 

As water flows across the sand, underwater sand ridges called antidunes form on the creek bed, gathering water. When the water pressure is too great, the dams break, sending down a wave, or surge about every 20 seconds.

Recently, the park service conducted a public comment period for initial proposed ideas for Great Sand Dunes National Park and Preserve Transportation and Transit Plan to focus on relieving congestion and to allow visitors to have a more enjoyable experience. The comment period ended March 29, and currently, the park service is analyzing all comments and is expected to issue a draft environmental assessment by late fall. A final decision on the plan is expected to be issued in early 2025.