Cordilleras Creek is a 3.8-mile-long northward-flowing stream originating in the Pulgas Ridge Open Space Preserve in the foothills of the Santa Cruz Mountains. It forms the border between San Carlos and Redwood City in San Mateo County, California, United States before entering Smith Slough where its waters course to Steinberger Slough and thence to San Fra…Cordilleras Creek is a 3.8-mile-long northward-flowing stream originating in the Pulgas Ridge Open Space Preserve in the foothills of the Santa Cruz Mountains. It forms the border between San Carlos and Redwood City in San Mateo County, California, United States before entering Smith Slough where its waters course to Steinberger Slough and thence to San Francisco Bay.