page_title: Los Trancos Creek
section_title: Ecology
hierarchical_section_title: Los Trancos Creek / Ecology
caption_attribution_description: English: Stanford University replaced their old non-functional fish ladder on Los Trancos Creek in the Jasper Ridge Biological Preserve so that Steelhead trout can get around their diversion dam to a man-made reservoir called Felt Lake. Eastern Santa Cruz Mountains foothills, Stanford University campus, California. The new one does not seem to be working either. In the foreground you can see the old cement ditch that used to divert creek water to Lake Lagunita at Stanford.
context_page_description: Los Trancos Creek is a creek that flows northerly from Monte Bello Ridge on the northeast slope of the Santa Cruz Mountains to its confluence with San Francisquito Creek at Stanford University in California, United States. The creek forms the boundary between northwestern Santa Clara County and southeastern San Mateo County.
context_section_description: In 1929 Stanford installed a diversion dam on Los Trancos Creek to its Felt Lake water storage reservoir. The dam, located just below the intersection of Arastradero and Alpine Roads, blocked access of anadromous steelhead trout (Oncorhynchus mykiss) to over 3 miles (4.8 km) of pristine upstream spawning grounds. In 2009, Stanford University completed construction of a new fish screen and ladder as the previous fish ladder was an "Alaska Steep Pass" designed for much higher flows. The upper watershed is wholly protected within the Los Trancos Open Space Preserve just northwest of Page Mill Road and east of Skyline Boulevard. Spawning steelhead in Los Trancos Creek below the Felt Lake diversion dam vary from zero in drought years to several hundreds in wetter years and occurs from February to April. Steelhead spend two years in freshwater before heading to the Bay and field studies in the Stanford portion of Los Trancos Creek have found hundreds of young trout ranging from  ~140 per mile to nearly 600 per mile.
  From 2016 through 2020, a pair of bald eagles (Haliaeetus leucocephalus) has nested in a large eucalyptus tree near Felt Lake and the Pearson-Arastradero Preserve.
caption: A  Fish ladder on Los Trancos Creek constructed by Stanford University in 2009 enables steelhead trout to pass the Felt Lake Diversion Dam.
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