An article on 2008 visitation to Great Sand Dunes National Park contained this observation:
In keeping with the average number of visits, [park chief of interpretation and visitor services Carol] Sperling said an average flow year at Medano Creek, which streams past the southern face of the dunes and the visitor center, had an average year. "If the creek does not flow, that's when visitation really tanks," she said.
Incidentally, "Médano" is accented on the first syllable. It comes via Spanish from an Arabic word for ... sand dune.