The Parting of the Waters, looking southeast. North Two Ocean Creek splits into Atlantic Creek, flowing to the left in the photo, and Pacific Creek, flowing to the right. The wooden sign indicates that it is 3,488 miles to the Atlantic Ocean and 1,353 miles to the Pacific Ocean (Photo by Anne Carlson).
Near the southern boundary of Yellowstone National Park is a curious location—a pass on the Continental Divide that is so gentle, fish can swim across, moving from the Pacific to the Atlantic watershed!
In the contiguous 48, the Continental Divide follows the spine of the Rocky Mountains for approximately 3,000 miles. trails and roads through the Rockies frequently cross the divide. In fact, driving the main highways in Yellowstone National Park, you cross it in three different places! You can even hike the entire length of the divide from the Mexican border to the Canadian border on the Continental Divide National Scenic Trail… if you have five months to spare.
In some places, the divide is obvious, like a high mountain pass clearly separating the watersheds. But in other locations, the divide is barely perceptible. One of these unique, indiscernible locations is tucked into a wild corner of the Greater Yellowstone Ecosystem, named Two Ocean Pass.
Located in Wyoming’s Bridger-Teton National Forest, the high alpine meadow at Two Ocean Pass doesn’t look like a pass at all. The profile of the pass is so low that when the meadow is flooded in the spring during a wet year, a fish can swim from the Pacific watershed into the Atlantic watershed! This is how the Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) is believed to have originally colonized Yellowstone Lake following the end of the Pinedale glaciation about 14,000 years ago.
As the glacial ice receded, fish were not able to swim upstream in the Yellowstone River all the way to Yellowstone Lake due to the natural barrier of the Lower Falls. Thus, cutthroat trout likely colonized the lake by swimming across Two Ocean Pass and then were the only trout species living in the lake for thousands of years.
In addition to being a fish passage, another fascinating feature of Two Ocean Pass is the Parting of the Waters, a National Natural Landmark. Here, North Two Ocean Creek branches into two streams exactly along the Continental Divide, forming the aptly named Pacific Creek and Atlantic Creek. An old wooden sign posted at the Parting of the Waters indicates that it is 3,488 miles to the Atlantic Ocean and 1,353 miles to the Pacific Ocean, quite the “choose your own adventure” for a water droplet.
With thousands of miles to explore, the Continental Divide offers countless fascinating stories of human history, geology, hydrology, ecology, and more!
Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week’s contribution is from Annie Carlson, Research Coordinator at the Yellowstone Center for Resources, Yellowstone National Park.
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