Brian Domonkos straps on a pair of cross-country skis and glides through the trees along Mosquito Creek west of Fairplay.

It’s May, but there’s still snow in Colorado’s mountains near the headwaters of the South Platte River.

Domonkos, the Colorado Snow Survey supervisor, gets to work measuring how much snowpack is left from the winter to runoff into streams, rivers and reservoirs this summer.