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1989 Map of Grassy Lake Reservoir

Name: 1989 Topographic Map of Grassy Lake Reservoir
Creator: U.S. Geological Survey
Published: 1989
License: https://creativecommons.org/publicdomain/mark/1.0/

USGS Topo · Published 1989

About this map

Yellowstone National Park and the Targhee National Forest converge on this 1989 survey, where the high elevation of the Pitchstone Plateau drops away into a complex drainage of rivers and waterfalls. The southern reaches are defined by the Grassy Lake Reservoir and the John D Rockefeller Jr Memorial Parkway, reflecting the late-century management of these protected lands. Evidence of back-country access is visible through the Marysville Proposition Road and several pack trails that follow the rugged water courses.

Hydrology dominates the landscape, with significant features like Union Falls and Terraced Falls located along the Cascade River and its tributaries. For researchers of wilderness history, the map provides an exact record of the shoreline of Beula Lake and Hering Lake before modern shifts in park infrastructure. The detailed contouring illustrates the dramatic relief between the plateau and the Cascade Acres area near the park boundary.