Konrad Wothe / Waterfalls of Sol Duc River, Olympic National Park, Washington

Konrad Wothe / Waterfalls of Sol Duc River, Olympic National Park, Washington

Tim Fitzharris / Yampa River flowing through canyons, Dinosaur National Monument, Colorado

Tim Fitzharris / Silted river flowering through Glen Canyon National Recreation Area, Utah

Tim Fitzharris / Yampa River, Dinosaur National Monument, Colorado