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1958 Map of Detert Reservoir

Name: 1958 Topographic Map of Detert Reservoir
Creator: U.S. Geological Survey
Published: 1961
License: https://creativecommons.org/publicdomain/mark/1.0/

USGS Topo · Published 1961

About this map

Robert Louis Stevenson Memorial State Park anchors the southern portion of this 1958 survey, where the Mayacamas Mountains define a landscape of steep canyons and high peaks. The region's industrial legacy is clearly visible through a dense network of cinnabar and silver mining operations, including the Silverado Mine, Mirabel Mine, and the extensive Oat Hill Mine complex. These sites are linked by rugged routes like Livermore Road and the Old Grade, tracing the historical movement of ore and supplies through the mountains.

Water management and ranching history appear in the north with the Detert Reservoir and the Collayomi Valley floor. The map preserves the complex boundary intersections of Lake, Napa, and Sonoma counties, showcasing how the terrain dictated early land grants like Mallacomes or Moristul y Plan de Agua Caliente. From the sheer cliffs of The Palisades to the drainage of St Helena Creek, the map details a period when these hills were still actively worked by miners and ranchers.