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Glossary · Nature & Wildlife

Sierra Azul

The “Blue Mountains”: the Spanish name for the Santa Cruz Mountains south of Highway 17, now a 19,300-acre open space preserve with Mount Umunhum and El Sombroso.

The Midpeninsula Regional Open Space District manages the preserve. Its peaks include Mount Umunhum (3,486 feet), Mount Thayer and El Sombroso, and trails connect Lexington Reservoir on the west with Hicks Road on the east.

It protects the upper watersheds of Los Gatos Creek and Guadalupe Creek, with wooded canyons, chaparral and open meadows.

Sources

Questions people ask

What does Sierra Azul mean?

“Blue Mountains,” the Spanish name for the range south of today’s Highway 17.

How high is Mount Umunhum?

3,486 feet.

Related terms

  • El Sereno and El SombrosoThe two mountains on either side of Los Gatos Creek’s canyon above town: El Sereno to the southwest and El Sombroso to the southeast. Both are now open space preserves.
  • Lexington ReservoirThe reservoir above Los Gatos formed in 1952 by the James J. Lenihan Dam, which drowned the old towns of Lexington and Alma; now a county park for paddling, fishing and hiking.
  • Los Gatos CreekThe 24-mile creek that rises near Loma Prieta, fills Lexington and Vasona reservoirs and flows through Los Gatos and Campbell to the Guadalupe River in San Jose.

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