Yellowstone’s Little Two Ocean Lake

January 03, 2017

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Photographer: Ray Boren
Summary Author: Ray Boren

Yellowstone National Park’s small, elongated Isa Lake does something remarkable — and unexpected. Perched at Craig Pass (elevation 8,262 ft/2,518 m), and straddling North America’s Continental Divide, it 's believed to be the only natural lake in the world to drain into two different oceans — the Pacific and the Atlantic. Note that there are fabricated bodies of water that also drain into both the Atlantic and Pacific Oceans, notably the artificial Gatun Lake, which is part of the ocean-linking Panama Canal.

Winter snow is presently stacking up on the high watershed around Isa Lake, shown here blanketed with yellow spatterdock water lilies (Nuphar polysepala) and large lily pads in summertime photos taken on July 14, 2016. But when that snow melts in spring, the lake will swell with runoff. That’s when, as the National Park Service notes at the site, “the lake does something extraordinary.”

As a pond with two outlets, Isa Lake, when full to the brim, sends mountain water via small streams and by simple seepage to the two oceans. And, due to its position in the Rocky Mountains, it does so in a manner contrary to our compass-oriented expectations: The outflow on the lake’s EAST side eventually heads toward the Pacific Ocean, far to the WEST, via Yellowstone’s Shoshone Lake and Lewis River, and eventually the Snake and Columbia Rivers. Meanwhile, the outflow on the lake’s WEST side contributes to the park’s Firehole River, which ultimately sends its water EAST and SOUTH via the Missouri, Mississippi and other rivers to the Gulf of Mexico and the Atlantic Ocean.

Photo Details: Camera Model: NIKON D3200; Lens: AF-S DX VR Zoom-Nikkor 18-55mm f/3.5-5.6G; Focal Length: 18mm (35mm equivalent: 27mm); Aperture: ƒ/8.0; Exposure Time: 0.020 s (1/50); ISO equiv: 400.