The "Valley of the Little Captains" or Rancho Cañada de los Capitancillos is named for the cañada, or valley, through which Guadalupe Creek courses. The river was once used for recreation prior to the removal of the Guadalupe Dam.
Watershed and course
The Guadalupe Creek subwatershed drains. Heading downstream east from the peak of Mount Umunhum, Guadalupe Creek is joined on the left by Rincon Creek, then on the right by Los Capitancillos Creek before reaching Guadalupe Reservoir. Guadalupe Dam, built in 1935, formed the reservoir. The main purpose of the reservoir is to capture runoff from winter storms to recharge in the Alamitos percolation pond system during the summer. Below Guadalupe Dam, Guadalupe Creek follows Hicks Road, and just below the intersection of Reynolds Road is joined on the left first by perennial Cherry Springs Creek, which originates at Cherry Springs. Cherry Springs Creek has a small perennial tributary, Hicks Creek, which originates on the northern side of El Sombroso Peak and flows into Reynolds Creek from the west. The next Guadalupe River tributary is Pheasant Creek, which runs below Hicks Road between Pheasant and Wagner Roads to join Guadalupe Creek from the left. At the intersection of Shannon Road and Hicks Road, Guadalupe Creek is joined from the left next by Shannon Creek. Masson Dam, built in 1964, is a small diversion dam about upstream of Almaden Expressway. The dam conveys water into the Los Capitancillos percolation ponds continually, unless Guadalupe Reservoir spills, in which case diversion operations terminate until the rainy season ends. In 1999, Masson Dam, which had been a complete barrier to fish passage, was removed and then re-built, along with a fish ladder which was completed in 2000. Completed in 1962 and reconstructed in 1964, the Los Capitancillos percolation ponds occupy about 63 acres, from Almaden Expressway to Camden Road. Guadalupe creek crosses Almaden Expressway just before joining Los Alamitos Creek at Lake Almaden, the beginning of the Guadalupe River. Lake Almaden was historically a meadow but was formed by a gravel removing quarry operation. Guadalupe Creek has been entirely earthen since a short 500 foot section of concrete channel was removed near its confluence with Pheasant Creek.
Guadalupe Creek is impaired by mercury contamination. Historically, workers disposed of roasted mercury mining wastes, called calcines, and other waste in or near Guadalupe Creek and Los Alamitos Creek so that waste materials would be transported downstream by winter flows. Guadalupe Reservoir covers a former mercury ore processing area. Calcines and other mining wastes are still present along the banks of Guadalupe Creek above Camden Avenue, along the banks of upper Guadalupe Creek near the former Guadalupe Mine outside of the Almaden Quicksilver County Park. A partly vegetated mining waste pile is present at Hicks Flat on the opposite side of Guadalupe Creek from the main mine. A half-mile stretch of Guadalupe Creek between Almaden Expressway and Masson Dam was restored in 2001 as mitigation for the downtown San Jose flood control project. Restoration included removal of mercury-contaminated sediments and recreation of a meandering stream course with native vegetation. The California Office of Environmental Health Hazard Assessment has developed a safe eating for Guadelupe Creek, stating that no one should eat any fish caught here.
