High Quality Content by WIKIPEDIA articles! The Guadalupe River is a short river in California whose headwater creeks form in the Santa Cruz Mountains near the summit of Loma Prieta and Mount Umunhum. The river mainstem now begins on the Santa Clara Valley floor at the northern end of Lake Almaden, which is fed by Los Alamitos Creek and Guadalupe Creek, just downstream of Coleman Road in San Jose, California. From here it flows north through San Jose, emptying into the San Francisco Bay at the Alviso Slough after a traverse of 14 miles (23 km). Historically the Guadalupe River was even shorter, originating several miles further north, at the downstream end of a large willow swamp that is now Willow Glen. Its main tributary was known as Arroyo Seco de Guadalupe on 1860 maps and then as Arroyo Seco de Los Capitancillos on the 1876 Thompson & West maps. The Guadalupe River runs through the City of San Jose, California, although it serves as the eastern boundary of the City of Santa Clara and the western boundary of Alviso. Much of the river is surrounded by parks.