The annual rise and fall of the Yampa River in Dinosaur National Monument defines a unique ecosystem where cacti bloom in unison with wild roses and sunflowers along the river bank.

Photo by Tom Ross

The annual rise and fall of the Yampa River in Dinosaur National Monument defines a unique ecosystem where cacti bloom in unison with wild roses and sunflowers along the river bank.

Rise and fall of the Yampa River defines a unique ecosystem

The invisible rock stars of the animal kingdom in Yampa Canyon are endangered fish like the razorback sucker and the Colorado pikeminnow that occupy the top of the food chain but rarely are glimpsed by humans in part because they live their lives in the opaque silt-laden waters of the Yampa River.

Eric Kuhn, general manager of the Colorado River Water Conservation District, explained to the members of the Yampa River Awareness Project expedition that although the Yampa was flowing at 4,000 cubic feet per second as the rafts shoved off from Deerlodge Park, the flow would increase dramatically just below the confluence of the Green River.

That is because the Bureau of Reclamation was releasing about 4,300 cfs of cold, clear water from Flaming Gorge Reservoir, just upstream on the Green, in order to hit target flows needed to support spawning by the razorback suckers.

Later in the day, Pat Tierney — a professor and chairman of the Department of Recreation, Parks and Tourism at San Francisco State University — gathered the group on a sandbar, cobbled with stone, next to one of the most significant pikeminnow spawning beds in the Colorado River system.

“The pikeminnow migrate as much as 200 miles,” Tierney said. “They come from the White River into the Green and up to this gravel bar. There has been a natural ecosystem here for thousands of years. They have a right to survive.”

Scientists cannot directly view spawning pikeminnow because of the turbidity of the water, but they can “see” them spawning over specific spawning areas cobbled with river rocks thanks to radio tags. Mating begins within days of the mean daily water temperatures exceeding

64.4 degrees, Tierney said. After hatching, the juvenile fish drift downstream to a backwater that is cut off from the river’s main flow at the top but open to the current at the bottom. These warm backwaters provide abundant food for the first year of the pikeminnow’s life.

Tierney, who put in a lengthy stint as a National Park Service river ranger in Dinosaur, took the time during lunch stops along the river to point out thick veins of chirt that are ideal for toolmaking and occasionally found a piece of chirt that had been worked by ancient hands.

John Saunders, a longtime professor of outdoor education at Colorado Mountain College, told the group that it isn’t just the wild animals and plants that have depended on the river’s historic seasonal flows. The ancient Fremont people are thought to have used 147 kinds of plants found in the canyons. The native willows are exceptionally pliable, making them ideal for creating waterproof containers on the spot.

Today, progress is being made against the invasive tamarisk shrub that has been crowding out the willows that thrive on the sandbars. Dinosaur National Park Superintendent Mary Risser told the group that another imported species, the tamarisk beetle, which feeds exclusively on tamarisk, is making headway against the unwanted plant.

Saunders said the Fremonts used many of the canyon’s plants as a pharmacy. The willows contain salicylic acid, which is a compound found in aspirin. And the wild rose plants blooming at the boundary between box elder trees and sandbars is a good source of vitamin C.

In the predawn of our first morning on the river at Tee Pee Campground, we arose to find a small squadron of sphinx moths, resembling hummingbirds, pollinating the tiny, yellow blossoms of aromatic wild licorice. The plants were growing in the sand right at the edge of the spring’s peak water level.

Their dance with the flowers was a reminder that the natural order of life in Yampa Canyon is delicately balanced with the flows of a great Western river.

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