Livingston, Montana. The Yellowstone River flows 692 miles from its headwaters at the foot of Wyoming’s 12,156-foot high Younts Peak to it mouth, located about 20 miles west of the ugly, oily, boom town of Williston, North Dakota. The river is Montana’s longest and most historically important stream. Before the railroad era, the Yellowstone served as the European-American gateway to the lands and riches of southwestern Montana. In the 1870s, the Teton Lakota made their last, desperate stand along the Yellowstone against Imperial America. The Roche Jaune, as the French-Canadian fur trappers called the river, pushes more silt and water into the Missouri than any of the Mighty Mo’s other tributaries, including the James, Big Sioux, Platte, and Kaw rivers. The Yellowstone once dumped so much water into the Missouri that some 19th century frontiersmen considered the Yellowstone to be the parent stream of the Missouri. Modern hydrologists have proven that claim to be false.
The Yellowstone now carries far less water than in the 19th century. Today, the river is a shell of its former self. At this very moment, the river is hauling a mere 1,620 cubic feet per second passed the USGS stream gauge at Livingston, Montana. This amount of water is only 300 cubic feet per second more than the all-time low river stage at Livingston, set back in the drought year of 2001.
From Billings, Montana, to Gardiner, Montana, white, sun-bleached cobblestones line both sides of the river. Those cobblestones mark where water once flowed. Oddly, certain sections of the river valley resemble a wide, paved, gleaming white highway, with a thin sliver of river flowing nearby. The Yellowstone is shrinking for a variety of reasons.
Montana agriculture has a huge appetite for Yellowstone River water. Yellowstone Valley farmers pull millions of gallons of water from the stream each year to irrigate cropland. In Paradise Valley, south of Livingston, the irrigated valley bottomlands are dark green and lush, while the unirrigated uplands, (close to the towering peaks of the Absaroka mountain range) appear bone-dry and brown. The farmers use the Yellowstone to irrigate their alfalfa fields. The harvested alfalfa is fed to cattle. The cattle are then fed, in America’s fast food restaurants, to an increasingly obese U.S. population. When you look out at the greenery of Paradise Valley, you’re looking at the Yellowstone transformed from a wild, blue river into a green, uniform mono crop.
Another cause for the diminishment of the Yellowstone is the region’s ongoing drought. Southwest Montana and northwest Wyoming continue to suffer from low precipitation, clear skies, and high temperatures. These climatic conditions induce farmers to pull even more water from the river to irrigate their cow pastures and alfalfa fields.
Yet, the biggest culprit in the disappearance of the once voluminous Yellowstone is climate change. Climate change is delivering a one-two-three punch to the river. Climate change worsened the drought of 2012 and 2013. For the past two years, it has made temperatures warmer, the atmosphere drier, and evaporation rates higher. When the rains do fall, they increasingly fall from the sky as monsoonal downpours, rather than as slow, percolating showers so beneficial to agriculture.
Climate change has contributed to the spread of the pine beetle. A longer growing season and warmer winters have been a boon to the beetle. The bug has killed millions of trees across the Yellowstone basin. The death of those trees has impaired nature’s ability to regulate the Yellowstone River’s discharge rates. Pine trees hold snowmelt and rainwater in their pine needles, branches, trunks, and root systems. The trees are natural reservoirs, slowing the movement of run-off into the Yellowstone. In the past, pine trees helped keep the Yellowstone from yo-yo’ing up and down. Forestlands slowed run-off in the spring and summer and ensured the groundwater regeneration of the river during the low flow months of August and September. Now, with so much forestland dead or dying, massive amounts of snowmelt and rainwater run unimpeded into the river in the spring and early summer, forcing the river to bounce up quickly. In late summer and early fall, the river is dropping to new lows because the trees are no longer releasing water to the river through groundwater sources. All of this means the Yellowstone’s discharge rates have become erratic. The Yellowstone now runs excessively high or excessively low. Uniform, steady discharge rates are increasingly a thing of the past.
Climate change is also messing with the mountain snowpack. Since the late twentieth century, the Yellowstone basin has experienced a more rapid transition from winter to summer temperatures. This change in the region’s climate has caused the snowpack to melt sooner and faster than ever before. The Yellowstone flood of 1997 resulted from heavy rainfall and the rapid melting of the mountain snowpack. The melting of the mountain snowpack, which can now occur in a matter of a few weeks, means there is no meltwater to maintain the Yellowstone’s flows later in the summer, when the river is tapped heavily for irrigation. Back in the 1990s, it was common to see snow on the peaks of the Absaroka Mountains year-round. This year, the snow is completely gone from the mountaintops.
All of this news is deeply disturbing for what it means for Montana agriculture, the Montana economy, the Greater Yellowstone Ecosystem, and the Yellowstone River trout fishery. But we are just beginning to see the negative effects of climate change along the Yellowstone. As the planet continues to warm, the Yellowstone’s flow regime is going to become very unpredictable.